ELEMENTS
OF THE
THEORY AND PRACTICE
OF
CHYMISTRY·
Translated from the FRENCH of
M. MACQUER,
Member of the Royal Academy of Sciences, and Professor
of Medicine in the University of PARIS.
The FIFTH EDITION.
EDINBURGH:
Printed for ALEXANDER DONALDSON; and sold at his
Shop, No. 48, East Corner of St. Paul's Church-Yard,
London; and at Edinburgh.
M. DCC. LXXVII.
THE AUTHOR's PREFACE.
An hundred and fifty years are scarce elapsed since the clouds of
prejudice, which had long overspread the world, began to clear up,
and men were convinced, by cultivating the Sciences, and attending
to Nature, that no fanciful hypotheses would ever lead them to the
true causes of those various phenomena that incessantly and every
where meet the observer's eye; but that the narrow limits of the
human understanding confine the course of our researches to one
single path; namely, that of Experiment, or the Use of our Senses.
Yet, in this short period, Natural Philosophy hath risen to a high
pitch of improvement, and may with truth be said to have made much
greater advances towards perfection, since the experimental method was
introduced, than in the many ages before.
This is true with regard to every branch of Natural Philosophy; but
more particularly with regard to Chymistry. Though this Science cannot
be said to have ever existed without experiments, yet it laboured under
the same disadvantages with the rest; because those who studied it made
all their experiments with a view to confirm their own Hypotheses, and
in consequence of principles which had no foundation whatever, but in
their wild imaginations.
Hence arose that enormous heap, that incongruous jumble of facts, which
some time ago constituted all the knowledge of Chymists. Most of them,
and especially those who assumed the pompous title of Alchymists,
were persuaded that all the Metals were no other than Nature's rude
unfinished essays towards making Gold; which, by means of due coction
in the bowels of the earth, advanced gradually towards maturity, till
at last they were perfectly converted into that beautiful and precious
Metal.
On this principle, which, if not demonstrably false, is at least
utterly destitute of proof, and unsupported by a single observation,
they attempted to finish what Nature had begun, by procuring to the
imperfect Metals this much desired coction. To attain it they made
an infinite number of experiments and trials; which all conspired to
detect the falsity of their system, and to satisfy men of sense, that
the methods they employed were very far from answering the purpose.
However, as facts always promote the knowledge of Nature, it happened
that those experiments, though quite useless with regard to the end for
which they were originally made, proved the occasion of several curious
discoveries.
These lucky consequences of their mistaken labours raised the courage
of the Chymists, or rather Alchymists, who looked upon every such
instance of success as a new step towards the Grand Work, and greatly
increased the fond opinion they entertained of themselves, and of
their Art, which, on that account, they set up very high above all
other Sciences. Nay, they carried this notion of superiority so far,
as to hold the rest of mankind unworthy, or incapable, of rising to
such sublime knowledge. In consequence thereof Chymistry became an
occult and mysterious Science; its expressions were all tropes and
figures, its phrases metaphorical, and its axioms so many enigmas: in
short, an obscure unintelligible jargon is the justest character of the
Alchymistic Language.
Thus, by endeavouring to conceal their secrets, those gentlemen
rendered their Art useless to mankind, and brought it into deserved
contempt. But at length the genius of true philosophy prevailed in
Chymistry, as well as in the other Sciences. Some great men arose, who
had generosity enough to think their knowledge no otherways valuable
than as it proved of service to Society. They did their utmost to
introduce both the knowledge and the practice of many important
secrets, till then of no use; they drew aside the veil which hid the
charms of Chymistry; and that Science emerging from the profound
obscurity, in which it had for many ages lain concealed, gained the
admiration of the world as soon as it appeared in open day. Several
societies of ingenious men were formed in the most learned countries
of Europe, who vied with one another in their labours to execute the
noble scheme, and assisted each other by mutually communicating their
discoveries. Chymistry made the most rapid progress, enriching and
perfecting the Arts derived from, or depending on it. In a word, it
put on a new face, and became truly worthy of the title of Science;
founding its principles and its processes on solid experiments, and on
just consequences deduced from them.
Since that time the Art is become so extensive, by the numerous
discoveries which Chymists have already made, and are daily making,
that large volumes are required to contain a complete Treatise on the
subject. In short, Chymistry may now, in some degree, be compared
to Geometry: each of these Sciences takes in a most ample field of
inquiry, which every day enlarges very considerably; from each are
derived several Arts, not only useful but even necessary to Society;
each hath its Axioms and its undeniable principles, either demonstrated
from internal evidence, or founded on constant experience; so that
the one, as well as the other, may be reduced to certain fundamental
truths, on which all the rest are built. These fundamental truths
connected together, and laid down with order and precision, form what
we call the Elements of a Science. It is well known that there are
many such works relating to Geometry, but it is not so with regard to
Chymistry; there being very few books which treat of this Science in an
Elementary manner.
Yet it must be owned, that performances of this kind are exceedingly
useful. Many who have a relish for the Sciences, but have not leisure
to read elaborate Works which treat of them minutely, are glad to meet
with a book from which, without sacrificing too much of their time,
or neglecting their ordinary business, they may obtain a taste or
just notion of a Science that is not their principal study. Those who
incline to go farther, and learn more, may, by reading an elementary
tract, be enabled to understand Authors, who, as they commonly write
only for proficients in the Art, are obscure and hardly intelligible
to mere beginners. Nay, I presume to say, that an Elementary Treatise
of Chymistry may prove a very useful book, even to those who have made
some progress in the Science: for as it contains only the fundamental
propositions, and indeed is an abstract of the whole Art, it may help
them to recollect the most important parts of what they have read in
many different works, and fix in their memoirs the most essential
truths, which might else be either confounded with others, or entirely
forgot. And these are the motives which determined me to compose the
Work which I now offer to the Public.
The general Plan on which I proceed is to suppose my Reader an absolute
Novice in Chymistry; to lead him from the most simple truths, and such
as imply the lowest degree of knowledge, to such as are more complex,
and require a greater acquaintance with Nature. This order, which I
have laid down for my rule, hath obliged me to begin with examining
the most simple substances that we know, and which we consider as the
elements whereof others are composed; as, by knowing the properties of
these elementary parts, we are naturally led to those of their several
combinations; and, on the other hand, in order to know the properties
of compound bodies, it is necessary we should be first acquainted with
the properties of their principles. The same reason induced me, when
enquiring into the properties of one substance, to take no notice of
those which relate to any other substance not treated of before. For
example: as I treat of Acids before Metals, I say nothing under the
head of those Acids concerning their power of dissolving metals; that I
defer till I come to the subject of Metals: and thus I avoid speaking
prematurely of a substance with which I suppose my Reader wholly
unacquainted. And this method I was so much the more easily induced to
follow, that I know of no Chymical book written on the same Plan.
After discoursing of Elements in general, I treat next of such
substances as are immediately composed of them, and are, next to them,
the most simple: such are all saline substances. This head comprehends
mineral Acids, fixed Alkalis, and their several combinations; the
volatile sulphureous spirit, sulphur, phosphorus, and the Neutral salts
which have an earth or fixed Alkali for their basis: those which have
for their basis either a volatile Alkali, or some metallic substance,
are referred, according to my general Plan, to the heads under which I
treat of those substances.
Metallic substances are scarcely more compounded than the saline;
which induces me to consider them next. I begin with those which are
the most simple, or at least seem to be so; because their principles,
being very strongly connected together, are separated with the greatest
difficulty: such are the Metals properly so called; namely, Gold,
Silver, Copper, Iron, Tin, and Lead. After these come the Semi-metals
in order; to wit, Regulus of Antimony, Zinc, Bismuth, and Regulus of
Arsenic. Mercury being a doubtful substance, which some Chymists rank
with the Metals, and others with the Semi-metals, because it actually
possesses certain properties in common with each, I have treated of it
in a separate Chapter, which stands between the Metals and Semi-metals.
I next proceed to examine the several sorts of Oils, whether Vegetable,
which are divided into fat, essential, and empyreumatic; or Animal, and
Mineral Oils.
By examining these substances we obtain ideas of all the principles
which enter into the composition of Vegetable and Animal bodies; that
is, of those substances that are capable of fermentation: this enables
me to treat of fermentation in general; of its three different degrees
or kinds, the spirituous, acetous, and putrid; and of the products
of those fermentations, ardent spirits, acids analogous to those of
vegetables and animals, and volatile alkalis.
The order in which I treat of all those substances being different from
that in which they are obtained from compound bodies, I give, in a
distinct Chapter, a general idea of Chymical Decomposition, with a view
to shew the order in which they are separated, from the several bodies
in the composition whereof they are found. This brings them a second
time under review, and gives me an opportunity of distinguishing those
which exist naturally in compound bodies, from those which are only the
result of a new combination of some of their principles produced by the
fire.
The succeeding Chapter explains the late Mr Geoffroy's Table of
Affinities; which I take to be of great use at the end of an Elementary
tract like this, as it collects into one point of view the most
essential and fundamental doctrines which are dispersed through the
work.
I conclude with an account of the Construction of such Vessels and
Furnaces as are usually employed in Chymistry.
In this Part I say nothing of any manual operations, or the several
ways of performing Chymical processes; reserving these particulars for
my Treatise of Practical Chymistry, to which this must be considered as
an Introduction.
CONTENTS.
Elements of the THEORY of CHYMISTRY.
CHAP. I.
_Of the Principles of Bodies_ Page 1
Sect. 1. Of Air 2
Sect. 2. Of Water 3
Sect. 3. Of Earth 4
Sect. 4. Of Fire 5
Sect. 5. Of the Phlogiston 7
CHAP. II. _A general View of the Relations or
Affinities between Bodies_ 9
CHAP. III. _Of Saline Substances in general_ 11
Sect. 1. Of Acids 12
Sect. 2. Of Alkalis 14
Sect. 3. Of Neutral Salts 15
CHAP. IV. _Of the Several Sorts of Saline Substances._
Sect. 1. Of the Universal Acid 18
Sect. 2. Of the Nitrous Acid 22
Sect. 3. Of the Marine Acid 25
CHAP. V. _Of Lime_ 29
CHAP. VI. _Of Metallic Substances in general_ 34
CHAP. VII. _Of Metals_ 37
Sect. 1. Of Gold _ib._
Sect. 2. Of Silver 39
Sect. 3. Of Copper 44
Sect. 4. Of Iron 47
Sect. 5. Of Tin 52
Sect. 6. Of Lead 53
CHAP. VIII. _Of Quick-Silver_ 58
CHAP. IX. _Of the Semi-Metals._
Sect. 1. Of Regulus of Antimony 62
Sect. 2. Of Bismuth 69
Sect. 3. Of Zinc 70
Sect. 4. Of Regulus of Arsenic 72
CHAP. X. _Of Oil in general_ 76
Sect. 1. Of Charcoal 77
Sect. 2. Of Soap 78
CHAP. XI. _Of the Several Sorts of Oils._
Sect. 1. Of Mineral Oils 79
Sect. 2. Of Vegetable Oils 80
Sect. 3. Of Animal Oils 82
CHAP. XII. _Of Fermentation in general_ 83
CHAP. XIII. _Of the Spirituous Fermentation_ 84
CHAP. XIV. _Of the Acetous Fermentation_ 90
Sect. 1. Of Vinegar 91
Sect. 2. Of Tartar 93
CHAP. XV. _Of the Putrid Fermentation, or
Putrefaction_ 96
CHAP. XVI. _A general View of Chymical
Decomposition_ 101
Sect. 1. The Analysis of Vegetable Substances 102
Emulsions 104
Sect. 2. The Analysis of Animal Substances 106
Sect. 3. The Analysis of Mineral Substances 108
Of the Pyrites 110
Of Ores 112
CHAP. XVII. _Explanation of the Table of
Affinities_ 119
CHAP. XVIII. _The Theory of Constructing the
Vessels most commonly used in Chymistry_ 126
CHAP. XIX. _The Theory of Constructing the
Furnaces most commonly used in Chymistry_ 133
_Of Lutes_ 147
Elements of the PRACTICE of CHYMISTRY.
Introduction 153
PART I. OF MINERALS.
SECTION I.
Operations performed on Saline Mineral Substances.
CHAP. I. _Of the Vitriolic Acid._
1. PROCESS. To extract Vitriol from the Pyrites 159
2. To extract Sulphur from the Pyrites, and
other Sulphureous Minerals 162
3. To extract Alum from aluminous Minerals 165
4. To extract the Vitriolic Acid from Copperas
or Green Vitriol 170
5. To decompose Sulphur, and extract its Acid, by
burning it 174
6. To concentrate the Vitriolic Acid 176
7. To decompound Vitriolated Tartar by means of the
Phlogiston; or to compose Sulphur by combining the
Vitriolic Acid with the Phlogiston 179
CHAP. II. _Of the Nitrous Acid._
1. PROCESS. To Extract Nitre out of Nitrous Earths
and Stones. The Purification of Salt-Petre. Mother
of Nitre. Magnesia 181
2. To decompose Nitre by means of the Phlogiston.
Nitre fixed by Charcoal. _Clyssus_ of Nitre.
_Sal Polychrestum_ 186
3. To decompose Nitre by means of the Vitriolic Acid.
The Smoking Spirit of Nitre. _Sal de duobus._ The
Purification of Spirit of Nitre 191
CHAP. III. _Of the Marine Acid._
1. PROCESS. To extract Sea-salt from Sea-water, and
from Brine-springs. Epsom Salt 195
2. Experiments concerning the Decomposition of Sea-salt
by means of the Phlogiston. Kunckel's Phosphorus 197
3. To decompose Sea-salt by means of the Vitriolic Acid.
Glauber's Salt. The Purification and Concentration
of Spirit of Salt 211
4. To decompose Sea-salt by means of the Nitrous Acid.
_Aqua regis._ Quadrangular Nitre 217
CHAP. IV. _Of Borax._ 218
SECTION II.
Of Operations on Minerals.
CHAP. I. _Of Gold._
1. PROCESS. To separate Gold, by Amalgamation
with Mercury, from the Earths and Stones with which
it is found mixed 223
2. To dissolve Gold in _Aqua Regis_, and by that means
separate it from Silver. _Aurum Fulminans._ _Aurum
Fulminans_ reduced 227
3. To dissolve Gold by Liver of Sulphur 232
4. To separate Gold from all other Metalline substances
by means of Antimony 233
CHAP. II. _Of Silver._
1. PROCESS. To separate Silver from its Ore, by means
of Scorification with Lead 238
2. The refining of Silver by the Cupel 243
3. To purify Silver by Nitre 248
4. To dissolve Silver in _Aqua Fortis_, and thereby separate
it from every other Metalline substance. The Purification
of _Aqua Fortis_. Silver precipitated by Copper 250
5. To separate Silver from the Nitrous Acid by
Distillation. Crystals of Silver.
The Infernal Stone 254
6. To separate Silver from the Nitrous Acid by
Precipitation. _Luna Cornea._ _Luna Cornea_ reduced 256
7. To dissolve Silver, and separate it from Gold, by
Cementation 258
CHAP. III. _Of Copper._
1. PROCESS. To separate Copper from its Ore 262
2. To purify Black Copper, and render it malleable 264
3. To deprive Copper of its Phlogiston by
Calcination 266
4. To resuscitate the Calx of Copper, and reduce it
to Metal, by restoring its Phlogiston 267
5. To dissolve Copper in the Mineral Acids 268
CHAP. IV. _Of Iron._
1. PROCESS. To separate Iron from its Ore 270
2. To render Pig-iron and brittle Iron malleable 273
3. To convert Iron into Steel 274
4. The Calcination of Iron. Sundry Saffrons of Mars 276
5. Iron dissolved by the mineral Acids 277
CHAP V. _Of Tin._
1. PROCESS. To extract Tin from its Ore 279
2. The Calcination of Tin 280
3. The Dissolution of Tin by Acids 284
CHAP. VI. _Of Lead._
1. PROCESS. To extract Lead from its Ore 286
2. To separate Lead from Copper 289
3. The Calcination of Lead 292
4. To prepare Glass of Lead 293
5. Lead dissolved by the Nitrous Acid 295
CHAP. VII. _Of Mercury._
1. PROCESS. To extract Mercury from its Ore, or to
revivify it from Cinabar 298
2. To give Mercury, by the action of Fire, the
appearance of a Metalline Calx 301
3. To dissolve Mercury in the Vitriolic Acid. Turbith
Mineral 302
4. To combine Mercury with Sulphur. Æthiop's
Mineral 304
5. To sublime the Combination of Mercury and Sulphur
into Cinabar 306
6. To dissolve Mercury in the Nitrous Acid. Sundry
Mercurial Precipitates 307
7. To combine Mercury with the Acid of Sea-salt.
Corrosive Sublimate 308
8. Sweet Sublimate 312
9. The Panacea of Mercury 314
SECTION III.
Of Operations on the Semi-Metals.
CHAP. I. _Of Antimony._
1. PROCESS. To separate Antimony from its Ore 315
2. The common Regulus of Antimony 316
3. Regulus of Antimony precipitated by Metals 318
4. The Calcination of Antimony 321
5. Calx of Antimony reduced to a Regulus 323
6. Antimony calcined with Nitre. Liver of Antimony.
_Crocus Metallorum_ 325
7. Another Calcination of Antimony with Nitre.
Diaphoretic Antimony. _Materia Perlata_.
_Clyssus_ of Antimony 326
8. Calx of Antimony vitrified 330
9. Kermes Mineral 331
10. Regulus of Antimony dissolved in the Mineral
Acids 335
11. Regulus of Antimony combined with the Acid of
Sea-salt Butter of Antimony. Cinabar of Antimony 338
12. Butter of Antimony decompounded by means of
Water only. _Pulvis Algaroth_, or _Mercurius Vitæ_.
The Philosophic Spirit of Vitriol 342
13. Bezoar Mineral. The Bezoartic Spirit of Nitre 343
14. Flowers of Antimony 347
15. Regulus of Antimony converted into Flowers 348
CHAP. II. _Of Bismuth._
1. PROCESS. To extract Bismuth from its Ore 350
2. Bismuth dissolved by Acids. Magistery of Bismuth.
Sympathetic Ink 352
CHAP. III. _Of Zinc._
1. PROCESS. To extract Zinc from its Ore, or
Calamine 357
2. To sublime Zinc into Flowers 359
3. To combine Zinc with Copper. Brass. Prince's
Metal, &c. 361
4. Zinc dissolved in the Mineral Acids 365
CHAP. IV. _Of Arsenic._
1. PROCESS. To extract Arsenic from its matrix.
Zafre or Smalt 367
2. To separate Arsenic from Sulphur 371
3. To give Arsenic the Metalline Form. Regulus of
Arsenic 374
4. To distil the Nitrous Acid by the interposition
of Arsenic. Blue _Aqua Fortis_. A new Neutral Salt
of Arsenic 377
5. To alkalizate Nitre by Arsenic 379
PART II. OF VEGETABLES.
SECTION I. Operations on unfermented Vegetables.
CHAP. I. _Of the Substances obtained from
Vegetables by Expression only._
1. PROCESS. To express and depurate the juice of a
Plant, containing its Essential Salt. The
crystallization of that Salt 383
2. To draw the Oils out of Kernels, Seeds, and Fruits,
by Expression 386
3. To draw the Essential Oils of certain Fruits by
Expression 387
CHAP. II. _Of the Substances obtained from
Vegetables by Triture._
1. PROCESS. To make the Extract of a Plant by
Trituration 389
2. To extract from Seeds and Kernels, by
Trituration, the matter of Emulsions 392
CHAP. III. _Of Operations on Fat Oils._
1. PROCESS. To attenuate Fat Oils, and change their
nature, by exposing them to the action of fire, and
distilling them 395
2. To combine Fat Oils with Acids. The decomposition
of this combination 398
3. To combine Fat Oils with Fixed Alkalis. Hard and
Soft Soap. The decomposition of Soap 400
4. To combine Fat Oils with Sulphur 405
5. To combine Fat Oils with Lead, and the Calces of
Lead. The Basis of Plasters. The decomposition of
this combination 406
CHAP. IV. _Of the substances obtained from Vegetables with
a degree of heat not exceeding that of boiling water._
1. PROCESS. To obtain from Plants, by distilling them
with the mean degree of heat between freezing and
boiling water, a liquor impregnated with their
Principle of Odour 408
2. To extract the Fat Oils of Plants by Decoction in
boiling water. Cacao-Butter 410
3. To extract the Essential Oils of Plants by
Distillation with the heat of boiling water.
Distilled Water 412
4. To extract the Essential Oils of Plants by
distillation _per descensum_ 418
5. Infusions, Decoctions, and Extracts of Plants 419
CHAP. V. _Of Operations on Essential Oils._
1. PROCESS. The Rectification of Essential Oils 422
2. To fire Oils by combining them with highly
concentrated Acids: instanced in Oil of Turpentine 426
3. To combine Essential Oils with mineral Sulphur.
Balsam of Sulphur. This composition decompounded 434
4. To combine Essential Oils with Fixed Alkalis.
Starkey's Soap 438
CHAP. VI. _Of the Substances obtained from Vegetables
by means of a graduated heat, from that of boiling
water, to the strongest that can be applied to them
in close vessels._
1. PROCESS. To analyze vegetable substances that
yield neither a Fat nor an Essential Oil: instanced
in Guaiacum-Wood 440
2. To analyze a vegetable substance which yields the
same principles as are obtained from Animal matters:
instanced in Mustard-seed 445
CHAP. VII. _Of the Substances obtained from
Vegetables by Combustion._
1. PROCESS. To procure a Fixed, Caustic, Alkaline
Salt from a vegetable substance, by burning it in
the open air 448
2. To procure the Fixed Salt of a Plant, by burning
it after the manner of Tachenius 453
3. To render Fixed Alkalis very Caustic by means of
Lime. The Caustic Stone 455
4. The Analysis of Soot 457
CHAP. VIII. _The Analyses of some particular
substances belonging to the Vegetable Kingdom._
1. PROCESS. Analysis of the Native Balsams: instanced
in Turpentine 460
2. The Analysis of Resins: instanced in Benjamin.
The Flowers and Oil of Benjamin 463
Reflections on the Nature and Properties of Camphor 465
3. The Analysis of Bitumens: instanced in Amber.
The Volatile Salt and Oil of Amber 467
4. The Analysis of Bee's Wax, and such Oily Compounds
as are analogous to it 472
5. The Saccharine juices of Plants analyzed: instanced
in Honey 474
6. Gummy substances analyzed: instanced in Gum
Arabic 476
SECTION II. Of Operations on Fermented Vegetable
Substances.
CHAP. I. _Of the Product of Spirituous Fermentation._
1. PROCESS. To make Wine of Vegetable Substances
that are susceptible of Spirituous Fermentation 478
2. To draw an Ardent Spirit from substances that have
undergone the Spirituous Fermentation. The Analysis
of Wine 482
3. To dephlegmate Spirit of Wine by the means of
Fixed Alkalis. Spirit of Wine analyzed 486
CHAP. II. _Spirit of Wine combined with different
Substances._
1. PROCESS. To combine Spirit of Wine with the Vitriolic
Acid. This combination decompounded. Rabel's
Water. Æther. Sweet Oil of Vitriol. Hoffman's
Anodyne Mineral Liquor 492
2. Spirit of Wine combined with Spirit of Nitre.
Sweet Spirit of Nitre 503
3. Spirit of Wine combined with the Acid of Sea-salt.
Dulcified Spirit of Salt 508
4. Oils, or Oily matters, that are soluble in Spirit of
Wine, separated from Vegetables, and dissolved, by
means of that Menstruum. Tinctures; Elixirs;
Varnishes. Aromatic Strong Waters 510
CHAP. III. _Of Tartar._
1. PROCESS. Tartar analyzed by distillation. The Spirit,
Oil, and Alkaline Salt of Tartar 514
2. The depuration of Tartar. Cream and Crystals of
Tartar 517
CHAP. IV. _Crystal of Tartar combined with several
substances._
1. PROCESS. Crystal of Tartar combined with Absorbent
Earths. Soluble Tartars 519
2. Crystal of Tartar combined with Fixed Alkalis. The
Vegetable Salt. Saignette's Salt. The decomposition
of Soluble Tartar 524
3. Crystal of Tartar combined with Iron. Chalybeated
Tartar. Tincture of Steel with Tartar. Soluble
Chalybeated Tartar 528
4. Crystal of Tartar combined with the reguline
part of Antimony. Stibiated or Emetic Tartar 534
CHAP. V. _Of the Product of Acetous Fermentation._
1. PROCESS. Substances susceptible of the Acetous
Fermentation turned into Vinegar 536
2. To concentrate Vinegar by Frost 540
3. Vinegar analyzed by distillation 542
CHAP. VI. _The Acid of Vinegar combined with
different Substances._
1. PROCESS. The Acid of Vinegar combined with Alkaline
Substances. Foliated Salt of Tartar, or Regenerated
Tartar. Decomposition of that Salt 547
2. The Acid of Vinegar combined with Copper. Verdegris.
Crystals of Copper. This combination decompounded.
Spirit of Verdegris 550
3. The Acid of Vinegar combined with Lead. Ceruse.
Salt or Sugar of Lead. This combination
decompounded 552
CHAP. VII. _Of the Putrid Fermentation of Vegetable Substances._
1. PROCESS. The Putrefaction of Vegetables 557
2. Putrefied Vegetable substances analyzed 559
PART III. Of Operations on Animal Substances.
CHAP. I. _Of Milk._
1. PROCESS. Milk separated into Butter, Curd, and
Whey: instanced in Cow's Milk 562
2. Butter analyzed by distillation 566
3. The Curd of Milk analyzed by distillation 569
4. Whey analyzed 571
CHAP. II. _Of the Substances which compose an Animal Body._
1. PROCESS. Blood analyzed: instanced in Bullock's
Blood 574
2. Flesh analyzed: instanced in Beef 580
3. Bones analyzed: instanced in Ox-bones 583
4. Animal Fat analyzed: instanced in Mutton-Suet 584
5. Eggs analyzed: instanced in Pullet's Eggs 586
CHAP. III. _Of Animal Excrements._
1. PROCESS. Dung analyzed: instanced in Human Excrement.
Mr. Homberg's Phosphorus 588
2. Human Urine analyzed 596
CHAP. IV. _Of Volatile Alkalis._
1. PROCESS. Volatile Alkalis rectified and
depurated 599
2. Volatile Alkalis combined with Acids. Sundry
Ammoniacal Salts. Sal Ammoniac 602
3. Sal Ammoniac decompounded by Acids 607
4. Sal Ammoniac decompounded by Fixed Alkalis.
Volatile Salt. The Febrifuge of Sylvius 608
5. Sal Ammoniac decompounded by Absorbent Earths
and Lime. Volatile Spirit of Sal Ammoniac. Fixed
Sal Ammoniac. Oil of Lime 611
6. Volatile Alkalis combined with oily matters.
A Volatile Oily Aromatic Salt 616
[Illustration: Decorative Scroll]
ELEMENTS
OF THE
THEORY OF CHYMISTRY.
CHAP. I.
_Of the_ PRINCIPLES _of_ BODIES.
The object and principal end of Chymistry, is to separate the different
substances that enter into the composition of bodies; to examine
each of them apart; to discover their properties and relations;
to decompose, if possible, those very substances; to compare them
together, and combine them with others; to re-unite them again into one
body, so as to reproduce the original compound with all its properties;
or even to produce new compounds that never existed among the works of
nature, from mixtures of other matters differently combined.
But this Analysis, or Decomposition, of bodies is finite; we being
unable to carry it beyond a certain limit. In whatever way we attempt
to go further, we are always stopped by substances in which we can
produce no change, which will not admit of being resolved into others,
and which stand as so many firm barriers obstructing our progress.
To these substances we may, in my opinion, give the title of Principles
or Elements: at least, with regard to us, they are really such. Of this
sort the principal are Earth, Water, Air, and Fire. For though there
is ground to believe that these are not the primary component parts,
or the most simple elements, of matter; yet, as we know by experience,
that our senses cannot possibly discover the principles of which they
are composed, it seems more reasonable to fix upon them, and consider
them as simple homogeneous bodies, and the principles of the rest, than
to fatigue our minds with vain conjectures about the parts or elements
of which they may consist; seeing there is no criterion by which we
can know whether we have hit upon the truth, or whether the notions we
have formed are mere fancies. We shall therefore consider these four
substances as the principles or elements of all the various compounds
which nature presents to our inquiries: because, of all those we have
as yet discovered, they are in fact the most simple; and because all
our decompositions, all our experiments on other bodies, plainly prove
that they are at last resolvable into these primary parts.
These principles do not enter in the same proportion into all bodies:
there are even some mixts in the composition of which this or that
particular principle is not to be found. Thus Air and Water seem
to be wholly excluded from the texture of Metals; at least all the
experiments that have hitherto been made on them seem to confirm this
opinion.
The substances composed immediately of these _first_ Elements we
shall call _secondary_ Principles; because in reality their several
combinations with each other, the interchangeable coalitions that take
place between them, constitute the different natures of all other
bodies; which, as they result from the union both of primary and
secondary principles, are properly entitled to the name of Compounds or
Mixts.
Before we enter upon the examination of Compound Substances, it is
necessary to consider with some attention the most Simple ones, or our
four first principles, in order to discover their chief properties.
SECTION I.
_Of_ AIR.
Air is that Fluid which we constantly breathe, and which surrounds the
whole surface of the terrestrial globe. Being heavy, like all other
bodies, it penetrates into all places that are not either absolutely
inaccessible, or filled with some other body heavier than itself.
Its principal property is to be susceptible of condensation and
rarefaction; so that the very same quantity of Air may occupy a much
greater, or a much smaller space, according to the different state it
is in. Heat and cold, or, if you will, the presence and the absence
of the particles of Fire, are the most usual causes, and indeed
the measures, of its condensation and rarefaction: for if a certain
quantity of Air be heated, its bulk enlarges in proportion to the
degree of heat applied to it; the consequence of which is, that the
same space now contains fewer particles of Air than it did before. Cold
again produces just the opposite effect.
On this property which Air has, of being condensed and rarefied by
heat, its elasticity or springiness chiefly depends. For if Air were
forced by condensation into a less compass than it took up before, and
then exposed to a very considerable degree of cold, it would remain
quite inactive, without exerting such an effort as it usually makes
against the compressing body. On the other hand, the elasticity of
heated Air arises only from hence, that being rarefied by the action of
Fire, it requires much more space than it occupied before.
Air enters into the composition of many substances, especially
vegetable and animal bodies: for by analysing most of them such a
considerable quantity thereof is extricated, that some naturalists
have suspected it to be altogether destitute of elasticity when thus
combined with the other principles in the composition of bodies.
According to them, the efficacy of the elastic power of the Air is so
prodigious, and its force when compressed so excessive, that it is
not possible the other component parts of bodies should be able to
confine so much of it, in that state of compression which it must needs
undergo, if retaining its elasticity it were pent up among them.
However that be, this elastic property of the Air produces the most
singular and important phenomena, observable in the resolution and
composition of bodies.
SECTION II.
_Of_ WATER.
Water is a thing so well known, that it is almost needless to attempt
giving a general idea of it here. Every one knows that it is a
transparent, insipid substance, and usually fluid. I say it is usually
so; for being exposed to a certain degree of cold it becomes solid:
solidity therefore seems to be its most natural state.
Water exposed to the Fire grows hot; but only to a limited degree,
beyond which its heat never rises, be the force of Fire applied to it
ever so violent: it is known to have acquired this degree of heat by
its boiling up with great tumult. Water cannot be made hotter, because
it is volatile, and incapable of enduring the heat, without being
evaporated and entirely dissipated.
If such a violent and sudden heat be applied to Water, as will not
allow it time to exhale gently in vapours, as when, for instance,
a small quantity thereof is thrown upon a metal in fusion, it is
dissipated at once with vast impetuosity, producing a most terrible and
dangerous explosion. This surprising effect may be deduced from the
instantaneous dilatation of the parts of the Water itself, or rather
of the Air it contains. Moreover, Water enters into the texture of
many bodies, both compounds and secondary principles; but, like Air,
it seems to be excluded from the composition of all metals and most
minerals. For although an immense quantity of Water exists in the
bowels of the Earth, moistening all its contents, it cannot be thence
inferred, that it is one of the principles of minerals. It is only
interposed between their parts; for they may be entirely divested of
it, without any sort of decomposition: indeed it is not capable of an
intimate connection with them.
SECTION III.
_Of_ EARTH.
We observed that the two principles above treated of are volatile; that
is, the action of Fire separates them from the bodies they help to
compose, carrying them quite off, and dissipating them. That of which
we are now to speak, namely Earth, is fixed, and, when it is absolutely
pure, resists the utmost force of Fire. So that, whatever remains of
a body, after it hath been exposed to the power of the fiercest Fire,
must be considered as containing nearly all its earthy principle,
and consisting chiefly thereof. I qualify my expression thus for two
reasons: the first is, because it often happens, that this remainder
does not actually contain all the Earth which existed originally in
the mixt body decomposed by Fire; since it will afterwards appear that
Earth, though in its own nature fixed, may be rendered volatile by
being intimately united with other substances which are so; and that,
in fact, it is common enough for part of the Earth of a body to be thus
volatilized by its other principles: the second is, that what remains
after the calcination of a body is not generally its earth in perfect
purity, but combined with some of its other principles, which, though
volatile in their own natures, have been fixed by the union contracted
between it and them. We shall, in the sequel, produce some examples to
illustrate this theory.
Earth, therefore, properly so called, is a fixed principle, which is
permanent in the Fire. There is reason to think it very difficult, if
not impossible, to obtain the earthy principle entirely free from every
other substance: for after our utmost endeavours to purify them, the
Earths we obtain from different compounds are found to have different
properties, according to the different bodies from which they are
procured; or else, if those Earths be pure, we must allow them to be
essentially different, seeing they have different properties.
Earth, in general, with regard to its properties, may be distributed
into _fusible_, and _unfusible_; that is, into Earth that is capable
of melting or becoming fluid in the Fire, and Earth that constantly
remains in a solid form, never melting in the strongest degree of heat
to which we can expose it.
The former is also called _vitrifiable_, and the second _unvitrifiable_
Earth; because, when Earth is melted by the force of Fire, it becomes
what we call _Glass_, which is nothing but the parts of Earth brought
into nearer contact, and more closely united by the means of fusion.
Perhaps the Earth, which we look upon as incapable of vitrification,
might be fused if we could apply to it a sufficient degree of heat.
It is at least certain, that some Earths, or stones, which separately
resist the force of Fire, so that they cannot be melted, become
fusible when mixed together. Experience convinced Mr. du Hamel that
lime-stone and slate are of this kind. It is however undoubtedly true,
that one Earth differs from another in its degree of fusibility: and
this gives ground to believe, that there may be a species of Earth
absolutely unvitrifiable in its nature, which, being mixed in different
proportions with fusible Earths, renders them difficult to melt.
Whatever may be in this, as there are Earths which we are absolutely
unable to vitrify, that is a sufficient reason for our division of
them. Unvitrifiable Earths seem to be porous, for they imbibe Water;
whence they have also got the name of _Absorbent Earths_.
SECTION IV.
_Of_ FIRE.
The Matter of the Sun, or of Light, the Phlogiston, Fire, the
Sulphureous Principle, the Inflammable Matter, are all of them names
by which the Element of Fire is usually denoted. But it should seem,
that an accurate distinction hath not yet been made between the
different states in which it exists; that is, between the phenomena of
Fire actually existing as a principle in the composition of bodies, and
those which it exhibits when existing separately and in its natural
state: nor have proper distinct appellations been assigned to it in
those different circumstances. In the latter state we may properly give
it the names of Fire, Matter of the Sun, of Light, and of Heat; and
may consider it as a substance composed of infinitely small particles,
continually agitated by a most rapid motion, and, of consequence,
essentially fluid.
This substance, of which the sun may be called the general reservoir,
seems to flow incessantly from that source, diffusing itself over the
world, and through all the bodies we know; but not as a principle, or
essential part of them, since they may be deprived thereof, at least
in a great measure, without suffering any decomposition. The greatest
change produced on them, by its presence or its absence, is the
rendering them fluid or solid: so that all other bodies may be deemed
naturally solid; Fire alone essentially fluid, and the principle of
fluidity in others. This being presupposed, Air itself might become
solid, if it could be entirely deprived of the Fire it contains; as
bodies of most difficult fusion become fluid, when penetrated by a
sufficient quantity of the particles of Fire.
One of the chief properties of this pure Fire is to penetrate easily
into all bodies, and to diffuse itself among them with a sort of
uniformity and equality: for if a heated body be contiguous to a cold
one, the former communicates to the latter all its excess of heat,
cooling in exact proportion as the other warms, till both come to have
the very same degree of heat. Heat, however, is naturally communicable
soonest to the upper parts of a body; and consequently, when a body
cools, the under parts become soonest cold. It hath been observed, for
instance, that the lower extremity of a heated body, freely suspended
in the air, grows cold sooner than the upper; and that, when a bar of
iron is red-hot at one end, and cold at the other, the cold end is much
sooner heated by placing the bar so that the hot end may be undermost,
than, when that end is turned uppermost. The levity of the matter of
Fire, and the vicinity of the Earth, may possibly be the causes of this
phenomenon.
Another property of Fire is to dilate all bodies into which it
penetrates. This hath already been shewn with regard to Air and Water;
and it produces the same effect on Earth.
Fire is the most powerful agent we can employ to decompose bodies; and
the greatest degree of heat producible by man, is that excited by the
rays of the sun collected in the focus of a large burning-glass.
SECTION V.
_Of the_ PHLOGISTON.
From what hath been said concerning the nature of Fire, it is
evidently impossible for us to fix and confine it in any body. Yet the
phenomena attending the combustion of inflammable bodies shew, that
they really contain the matter of Fire as a constituent principle.
By what mechanism then is this fluid, which is so subtle, so active,
so difficult to confine, so capable of penetrating into every other
substance in nature; how comes it, I say, to be so fixed as to make
a component part of the most solid bodies? It is no easy matter to
give a satisfactory answer to this question. But, without pretending
to guess the cause of the phenomenon, let us rest contented with the
certainty of the fact, the knowledge of which will undoubtedly procure
us considerable advantages. Let us therefore examine the properties of
Fire thus fixed, and become a principle of bodies. To this substance,
in order to distinguish it from pure and unfixed Fire, the Chymists
have assigned the peculiar title of the _Phlogiston_, which indeed is
no other than a Greek word for the Inflammable Matter; by which latter
name, as well as by that of the Sulphureous Principle, it is also
sometimes called. It differs from elementary Fire in the following
particulars. 1. When united to a body, it communicates to it neither
heat nor light. 2. It produces no change in its state, whether of
solidity or fluidity; so that a solid body does not become fluid by
the accession of the Phlogiston, and _vice versa_; the solid bodies to
which it is joined being only rendered thereby more apt to be fused by
the force of the culinary fire. 3. We can convey it from the body with
which it is joined into another body, so that it shall enter into the
composition thereof, and remain fixed in it.
On this occasion both these bodies, that which is deprived of the
Phlogiston and that which receives it, undergo very considerable
alterations; and it is this last circumstance, in particular, that
obliges us to distinguish the Phlogiston from pure Fire, and to
consider it as the element of Fire combined with some other substance,
which serves it as a basis for constituting a kind of secondary
principle. For if there were no difference between them, we should be
able to introduce and fix pure Fire itself, wherever we can introduce
and fix the Phlogiston: yet this is what we can by no means do, as will
appear from experiments to be afterwards produced.
Hitherto, Chymists have never been able to obtain the Phlogiston quite
pure, and free from every other substance: for there are but two ways
of separating it from a body of which it makes a part; to wit, either
by applying some other body with which it may unite the moment it
quits the former; or else by calcining and burning the compound from
which you desire to sever it. In the former case it is evident that we
do not get the Phlogiston by itself, because it only passes from one
combination into another; and in the latter, it is entirely dissipated
in the decomposition, so that no part of it can possibly be secured.
The inflammability of a body is an infallible sign that it contains
a Phlogiston; but from a body's not being inflammable, it cannot be
inferred that it contains none; for experiments have demonstrated that
certain metals abound with it, which yet are by no means inflammable.
We have now delivered what is most necessary to be known concerning the
principles of bodies in general. They have many other qualities besides
those above-mentioned; but we cannot properly take notice of them
here, because they presuppose an acquaintance with some other things
relating to bodies, of which we have hitherto said nothing; intending
to treat of them in the sequel as occasion shall offer. We shall only
observe in this place, that when animal and vegetable matters are
burnt, in such a manner as to hinder them from flaming, some part
of the Phlogiston contained in them unites intimately with their
most fixed earthy parts, and with them forms a compound, that can be
consumed only by making it red-hot in the open air, where it sparkles
and wastes away, without emitting any flame. This compound is called
a _Coal_. We shall inquire into the properties of this Coal under the
head of Oils: at present it suffices that we know in general what it
is, and that it readily communicates to other bodies the Phlogiston it
contains.
CHAP. II.
_A general View of the Relations or Affinities between Bodies._
Before we can reduce compound Bodies to the first principles above
pointed out, we obtain, by analysing them, certain substances which
are indeed more simple than the bodies they helped to compose, yet are
themselves composed of our primary principles. They are therefore at
one and the same time both principles and compounds; for which reason
we shall, as was before said, call them by the name of Secondary
Principles. Saline and oily matters chiefly constitute this class. But
before we enter upon an examination of their properties, it is fit we
lay before the reader a general view of what Chymists understand by
the Relations or Affinities of Bodies; because it is necessary to know
these, in order to a distinct conception of the different combinations
we are to treat of.
All the experiments hitherto made concur with daily observation to
prove, that different bodies, whether principles or compounds, have
such a mutual Conformity, Relation, Affinity, or Attraction, if you
will call it so, as disposes some of them to join and unite together,
while they are incapable of contracting any union with others. This
effect, whatever be its cause, will enable us to account for, and
connect together, all the phenomena that Chymistry produces. The nature
of this universal affection of matter is distinctly laid down in the
following propositions.
First, If any substance hath any Affinity or conformity with another,
the two will unite together, and form one compound.
Secondly, It may be laid down as a general rule, that all similar
substances have an Affinity with each other, and are consequently
disposed to unite; as water with water, earth with earth, _&c._
Thirdly, Substances that unite together lose some of their separate
properties; and the compounds resulting from their union partake of the
properties of those substances which serve as their principles.
Fourthly, The simpler any substances are, the more perceptible and
considerable are their Affinities: whence it follows, that the less
bodies are compounded, the more difficult it is to analyse them; that
is, to separate from each other the principles of which they consist.
Fifthly, If a body consist of two substances, and to this compound
be presented a third substance, that has no Affinity at all with one
of the two primary substances aforesaid, but has a greater Affinity
with the other than those two substances have with each other, there
will ensue a decomposition, and a new union; that is, the third
substance will separate the two compounding substances from each other,
coalesce with that which has an Affinity with it, form therewith a
new combination, and disengage the other, which will then be left at
liberty, and such as it was before it had contracted any union.
Sixthly, It happens sometimes that when a third substance is presented
to a body consisting of two substances, no decomposition follows;
but the two compounding substances, without quitting each other,
unite with the substance presented to them, and form a combination of
three principles: and this comes to pass when that third substance
has an equal, or nearly equal, Affinity with each of the compounding
substances. The same thing may also happen even when the third
substance hath no Affinity but with one of the compounding substances
only. To produce such an effect, it is sufficient that one of the
two compounding substances have to the third body a Relation equal,
or nearly equal, to that which it has to the other compounding
substance with which it is already combined. Thence it follows, that
two substances, which, when apart from all others, are incapable
of contracting any union, may be rendered capable of incorporating
together in some measure, and becoming parts of the same compound, by
combining with a third substance with which each of them has an equal
Affinity.
Seventhly, A body, which of itself cannot decompose a compound
consisting of two substances, because, as we just now said, they have
a greater affinity with each other than it has with either of them,
becomes nevertheless capable of separating the two by uniting with
one of them, when it is itself combined with another body, having a
degree of Affinity with that one, sufficient to compensate its own want
thereof. In that case there are two Affinities, and thence ensues a
double decomposition and a double combination.
These fundamental truths, from which we shall deduce an explanation
of all the phenomena in Chymistry, will be confirmed and illustrated
by applying them, as we shall do, to the several cases, of which our
design in this treatise obliges us to give a circumstantial account.
CHAP. III.
_Of Saline Substances in general._
If a particle of water be intimately united with a particle of earth,
the result will be a new compound, which, according to our third
proposition of Affinities, will partake of the properties of earth
and of water; and this combination principally forms what is called
a _Saline Substance_. Consequently every Saline Substance must have
an affinity with earth and with water, and be capable of uniting with
both or either of them, whether they be separate or mixed together:
and accordingly this property characterizes all Salts, or Saline
Substances, in general.
Water being volatile and Earth fixed, Salts in general are less
volatile than the former, and less fixed than the latter; that is,
fire, which cannot volatilize and carry off pure earth, is capable of
rarefying and volatilizing a Saline Substance; but then this requires a
greater degree of heat than is necessary for producing the same effects
on pure water.
There are several sorts of Salts, differing from one another, in
respect either of the quantity, or the quality of the earth in their
composition; or, lastly, they differ on account of some additional
principles, which not being combined with them in sufficient quantity
to hinder their Saline properties from appearing, permit them to retain
the name of Salts, though they render them very different from the
simplest Saline Substances.
It is easy to infer, from what has been said of Salts in general, that
some of them must be more, some less, fixed or volatile than others,
and some more, some less, disposed to unite with water, with earth,
or with particular sorts of earth, according to the nature or the
proportion of their principles.
Before we proceed further, it is proper just to mention the principle
reasons, which induce us to think that every Saline Substance is
actually a combination of earth and water, as we supposed at our
entering on this subject. The first is, the conformity Salts have
with earth and water, or the properties they possess in common with
both. Of these properties we shall treat fully, as occasion offers to
consider them, in examining the several sorts of Salts. The second
is, that all Salts may be actually resolved into earth and water by
sundry processes; particularly by repeated dissolution in water,
evaporation, desiccation, and calcination. Indeed the Chymists have
not yet been able to procure a Saline Substance, by combining earth
and water together. This favours a suspicion, that, besides these
two, there is some other principle in the composition of salts, which
escapes our researches, because we cannot preserve it when we decompose
them; but it is sufficient to our purpose, that water and earth are
demonstrably amongst the real principles of Saline Substances, and that
no experiment hath ever shewn us any other.
SECTION I.
_Of_ ACIDS.
Of all Saline Substances, the simplest is that called an _Acid_, on
account of its taste; which is like that of verjuice, sorrel, vinegar,
and other sour things, which, for the same reason, are also called
Acids. By this peculiar taste are Acids chiefly known. They have
moreover the property of turning all the blue and violet colours of
vegetables red, which distinguishes them from all other salts.
The form, under which Acids most commonly appear, is that of a
transparent liquor; though solidity is rather their natural state.
This is owing to their affinity with water; which is so great, that,
when they contain but just as much of it as is necessary to constitute
them Salts, and consequently have a solid form, they rapidly unite
therewith the moment they come into contact with it: and as the air
is always loaded with moisture and aqueous vapours, its contact alone
is sufficient to liquify them; because they unite with its humidity,
imbibe it greedily, and by that means become fluid. We therefore say,
they attract the moisture of the air. This change of a salt from a
solid to a fluid state, by the sole contact of the air, is also called
_Deliquium_; so that when a salt changes in this manner from a solid
into a fluid form, it is said to run _per deliquium_. Acids being the
simplest species of Saline bodies, their affinities with different
substances are stronger than those of any other sort of salt with
the same substances; which is agreeable to our fourth proposition
concerning Affinities.
Acids in general have a great affinity with earths: that with which
they most readily unite is the unvitrifiable earth to which we gave the
name of absorbent earth. They seem, not to act at all upon vitrifiable
earths, such as sand; nor yet upon some other kinds of earths, at least
while they are in their natural state. Yet the nature of these earths
may be in some measure changed, by making them red-hot in the fire,
and then quenching them suddenly in cold water: for, by repeating this
often, they are brought nearer to the nature of absorbent earths, and
rendered capable of uniting with Acids.
When an acid liquor is mixed with an absorbent earth, for instance with
chalk, these two substances instantly rush into union, with so much
impetuosity, especially if the acid liquor be as much dephlegmated,
or contain as little water, as may be, that a great ebullition is
immediately produced, attended with considerable hissing, heat, and
vapours, which rise the very instant of their conjunction.
From the combination of an acid with an absorbent earth there arises
a new compound, which some Chymists have called _Sal Salsum_; because
the Acid by uniting with the earth loses its sour taste, and acquires
another not unlike that of the common sea-salt used in our kitchens;
yet varying according to the different sorts of Acids and earths
combined together. The Acid at the same time loses its property of
turning vegetable blues and violet colours red.
If we inquire what is become of its propensity to unite with water, we
shall find that the earth, which of itself is not soluble in water,
hath, by its union with the Acid, acquired a facility of dissolving
therein; so that our _Sal Salsum_ is soluble in water. But, on the
other hand, the Acid hath, by its union with the earth, lost part of
the affinity it had with water; so that if a _Sal Salsum_ be dried,
and freed of all superfluous humidity, it will remain, in that dry
solid form, instead of attracting the moisture of the air, and running
_per deliquium_, as the Acid would do if it were pure and unmixed
with earth. However, this general rule admits of some exceptions; and
we shall have occasion in another place to take notice of certain
combinations of Acids with earths, which still continue to attract the
moisture of the air, though not so strongly as a pure Acid.
ACIDS have likewise a great affinity with the Phlogiston. When we come
to treat of each Acid in particular, we shall examine the combinations
of each with the Phlogiston: they differ so widely from one another,
and many of them are so little known, that we cannot at present give
any general idea of them.
SECTION II.
_Of_ ALKALIS.
Alkalis are Saline combinations, in which there is a greater proportion
of earth than in Acids. The principal arguments that may be adduced
to prove this fact are these: First; if they be treated in the manner
proposed above for analyzing Saline Substances, we obtain from them
a much greater quantity of earth than we do from Acids. Secondly; by
combining certain Acids with certain earths we can produce Alkalis; or
at least such saline compounds as greatly resemble them. Our third and
last argument is drawn from the properties of those Alkalis which, when
pure and unadulterated with any other principle, have less affinity
with water than Acids have, and are also more fixed, resisting the
utmost force of fire. On this account it is that they have obtained the
title of _Fixed_, as well as to distinguish them from another species
of Alkali, to be considered hereafter, which is impure and volatile.
Though fixed Alkalis, when dry, sustain the utmost violence of fire
without flying off in vapours, it is remarkable that, being boiled with
water in an open vessel, considerable quantities of them rise with the
steam: an effect which must be attributed to the great affinity between
these two substances, by means whereof water communicates some part of
its volatility to the fixed salt.
Alkalis freed of their superfluous humidity by calcination attract the
moisture of the air, but not so strongly as Acids: so that it is easier
to procure and preserve them in a solid form.
They flow in the fire, and are then capable of uniting with vitrifiable
earths, and of forming therewith true glass, which, however, will
partake of their properties, if they be used in sufficient quantity.
As they melt more readily than vitrifiable earth, they facilitate its
fusion; so that a weaker fire will reduce it to glass, when a fixed
Alkali is joined with it, than will melt it without that addition.
Alkalis are known by their taste, which is acrid and fiery; and by the
properties they possess of turning vegetable blues and violet colours
green; particularly syrop of violets.
Their affinity with acids is greater than that of absorbent earths; and
hence it comes to pass, that if an Alkali be presented to a combination
of an Acid with an absorbent earth, the earth will be separated from
the Acid by the Alkali, and a new union between the Acid and the Alkali
will take place. This is both an instance and a proof of our fifth
proposition concerning Affinities.
If a pure Alkali be presented to a pure Acid, they rush together with
violence, and produce the same phenomena as were observed in the
union of an absorbent earth with an Acid; but in a greater and more
remarkable degree.
Fixed Alkalis may in general be divided into two sorts: one of these
hath all the above-recited properties; but the other possesses some
that are peculiar to itself. We shall consider this latter sort more
particularly under the head of Sea-Salt.
SECTION III.
_Of_ NEUTRAL SALTS.
The Acid and the Alkali thus uniting mutually rob each other of their
characteristic properties; so that the compound resulting from their
union produces no change in the blue colours of vegetables, and
has a taste which is neither sour nor acrid, but saltish. A saline
combination of this kind is for that reason named _Sal Salsum_, _Sal
Medium_, of a _Neutral Salt_. Such combinations are also called by the
plain general name of _Salts_.
It must be observed that, in order to make these Salts perfectly
Neutral, it is necessary that neither of the two saline principles
of which they are compounded be predominant over the other; for in
that case they will have the properties of the prevailing principle.
The reason is this: neither of these saline substances can unite with
the other but in a limited proportion, beyond which there can be no
further coalition between them. The action by which this perfect union
is accomplished is termed _Saturation_; and the instant when such
proportions of the two saline substances are mixed together, that the
one is incorporated with as much of the other as it can possibly take
up, is called the _Point of Saturation_. All this is equally applicable
to the combination of an Acid with an absorbent earth.
The combination is known to be perfect, that is, the Point of
Saturation is known to be obtained, when, after repeated affusions of
an Acid in small quantities to an Alkali, or an absorbent earth, we
find those phenomena cease, which in such cases constantly attend the
conflict of union, as we said above, namely, ebullition, hissing, _&c._
and we may be assured the Saturation is complete when the new compound
hath neither an acid nor an acrid taste, nor in the least changes the
blue colours of vegetables.
Neutral salts have not so great an affinity with water as either Acids
or Alkalis have; because they are more compounded: for we observed
before, that the affinities of the most compounded bodies are generally
weaker than those of the most simple. In consequence hereof few Neutral
Salts, when dried, attract the moisture of the air; and those that do,
attract it more slowly, and in less quantity, than either Acids or
Alkalis do.
All Neutral Salts are soluble in water; but more or less readily, and
in a greater or smaller quantity, according to the nature of their
component principles.
Water made boiling hot dissolves a greater quantity of those salts
which do not attract the moisture of the air, than when it is cold;
and indeed it must be boiling hot to take up as much of them as it
is capable of dissolving: but as for those which run in the air, the
difference, if there be any, is imperceptible.
Some Neutral Salts have the property of shooting into crystals, and
others have it not.
The nature of Crystallization is this: Water cannot dissolve, nor keep
in solution, more than a determinate quantity of any particular Salt:
when therefore such a quantity of water is evaporated from the solution
of a Salt capable of crystallization, that the remainder contains just
as much Salt as it can dissolve, then by continuing the evaporation
the Salt gradually recovers its solid form, and concretes into several
little transparent masses called Crystals. These crystals have regular
figures, all differing from one another according to the species of
salt of which they are formed. Different methods of evaporating saline
solutions have different effects on the figure and regularity of the
crystals; and each particular sort of salt requires a peculiar method
of evaporation to make its crystals perfectly regular.
A solution of salt designed for crystallization is usually evaporated
by means of fire to a pellicle; that is, till the Salt begin to
concrete; which is perceived by a kind of thin dark skin that gathers
on the surface of the liquor, and is formed of the crystallized
particles of Salt. When this pellicle appears the solution is suffered
to cool, and the crystals form therein faster or slower, according to
the sort of salt in hand. If the evaporation be carried on briskly to
perfect dryness, no crystals will be formed, and only an irregular mass
of salt will be obtained.
The reasons why no crystals appear when the evaporation is hastily
performed, and carried on to dryness, are, first, that the particles
of salt, being always in motion while the solution is hot, have not
time to exert their mutual affinities, and to unite together as
crystallization requires: Secondly, that a certain quantity of water
enters into the very composition of crystals; which is therefore
absolutely necessary to their formation, and in a greater or smaller
proportion according to the nature of the Salt[1].
[1] Those who have the curiosity to see a more particular account
of the Crystallization of Neutral Salts, may read Mr. _Rouelle_'s
excellent Memoir on that subject, among those of the Academy of
Sciences for 1744.
If these crystallized salts be exposed to the fire, they first part
with that moisture which is not necessary to a saline concretion, and
which they retained only by means of their crystallization: afterwards
they begin to flow, but with different degrees of fusibility.
It must be observed, that certain salts melt as soon as they are
exposed to the fire; namely, those which retain a great deal of water
in crystallizing. But this fluor which they so readily acquire must be
carefully distinguished from actual fusion: for it is owing only to
their superfluous humidity, which heat renders capable of dissolving
and liquifying them; so that when it is evaporated the Salt ceases to
be fluid, and requires a much greater degree of fire to bring it into
real fusion.
The Neutral Salts that do not crystallize may, indeed, be dried by
evaporating the water which keeps them fluid; but by becoming solid
they acquire no regular form; they again attract the moisture of
the air, and are thereby melted into a liquor. These may be called
_Liquescent Salts_.
Most of the Neutral Salts, that consist of an Acid joined with a fixed
Alkali, or with an absorbent earth, are themselves fixed and resist
the force of fire; yet several of them, if they be dissolved in water,
and the solution boiled and evaporated, fly off along with the steams.
CHAP. IV.
_Of the several Sorts of Saline Substances._
SECTION I.
_Of the_ UNIVERSAL ACID.
The Universal Acid is so called, because it is in fact the Acid which
is most universally diffused through all nature, in waters, in the
atmosphere, and in the bowels of the earth. But it is seldom pure;
being almost always combined with some other substance. That from which
we obtain it with most ease, and in the greatest quantity, is Vitriol,
a mineral which we shall consider afterwards: and this is the reason
why it is called the _Vitriolic Acid_; the name by which it is best
known.
When the Vitriolic Acid contains but little phlegm, yet enough to give
it a fluid form, it is called _Oil of Vitriol_, on account of a certain
unctuosity belonging to it. In truth this name is very improperly
bestowed on it; for we shall afterwards see that, bating this
unctuousness, it has none of the properties of oils. But this is not
the only impropriety in names that we shall have occasion to censure.
If the Vitriolic Acid contain much water, it is then called _Spirit of
Vitriol_. When it does not contain enough to render it fluid, and so is
in a solid form, it is named the _Icy Oil of Vitriol_.
When Oil of Vitriol highly concentrated is mixed with water, they rush
into union with such impetuosity, that, the moment they touch each
other, there arises a hissing noise, like that of red-hot iron plunged
in cold water, together with a very considerable degree of heat,
proportioned to the degree to which the Acid was concentrated.
If, instead of mixing this concentrated Acid with water, you only
leave it exposed to the air for some time, it attracts the moisture
thereof, and imbibes it most greedily. Both its bulk and its weight are
increased by this accession; and if it be under an icy form, that is,
if it be concreted, the phlegm thus acquired will soon resolve it into
a fluid.
The addition of water renders the Vitriolic Acid, and indeed all other
Acids, weaker in one sense; which is, that when they are very aqueous
they leave on the tongue a much fainter taste of acidity, and are less
active in the solution of some particular bodies: but that occasions
no change in the strength of their affinities, but in some cases
rather enables them to dissolve several substances, which, when well
dephlegmated, they are not capable of attacking.
The Vitriolic Acid combined to the point of saturation with a
particular absorbent earth, the nature of which is not yet well known,
forms a Neutral Salt that crystallizes. This Salt is called _Alum_, and
the figure of its crystals is that of an octahedron, or solid of eight
sides. These octahedra are triangular pyramids, the angles of which are
so cut off that four of the surfaces are hexagons, and the other four
triangles.
There are several sorts of Alum, which differ according to the earths
combined with the Vitriolic Acid. Alum dissolves easily in water, and
in crystallization retains a considerable quantity of it; which is the
reason that being exposed to the fire it readily melts, swelling and
puffing up as its superfluous moisture exhales. When that is quite
evaporated, the remainder is called _Burnt Alum_, and is very difficult
to fuse. The Acid of the Alum is partly dissipated by this calcination.
Its taste is saltish, with a degree of roughness and astringency.
The Vitriolic Acid combined with certain earths forms a kind of
Neutral Salt called _Selenites_, which crystallizes in different forms
according to the nature of its earth. There are numberless springs
of water infected with dissolved Selenites; but when this Salt is
once crystallized, it is exceeding difficult to dissolve it in water
a second time. For that purpose a very great quantity of water is
necessary, and moreover it must boil; for as it cools most of the
dissolved Selenites takes a solid form, and falls in a powder to the
bottom of the vessel.
If an Alkali be presented to the Selenites, or to Alum, these
Salts, according to the principles we have laid down, will be
thereby decomposed; that is, the Acid will quit the earths, and join
the Alkali, with which it hath a greater affinity. And from this
conjunction of the Vitriolic Acid with a fixed Alkali there results
another sort of Neutral Salt, which is called _Arcanum duplicatum_,
_Sal de duobus_, and _Vitriolated Tartar_, because one of the fixed
Alkalis most in use is called Salt of Tartar.
Vitriolated Tartar is almost as hard to dissolve in water as the
Selenites. It shoots into eight-sided crystals, having the apices of
the pyramids pretty obtuse. Its taste is saltish, inclining to bitter;
and it decrepitates on burning coals. It requires a very great degree
of fire to make it flow.
The Vitriolic Acid is capable of uniting with the Phlogiston, or rather
it has a greater affinity with it than with any other body: whence
it follows, that all compounds, of which it makes a part, may be
decomposed by means of the Phlogiston.
From the conjunction of the Vitriolic Acid with the Phlogiston arises
a compound called _Mineral Sulphur_, because it is found perfectly
formed in the bowels of the earth. It is also called _Sulphur vivum_,
or simply _Sulphur_.
Sulphur is absolutely insoluble in water, and incapable of contracting
any sort of union with it. It melts with a very moderate degree of
heat, and sublimes in fine light downy tufts called _Flowers of
Sulphur_. By being thus sublimed, it suffers no decomposition, let
the operation be repeated ever so often; so that Sublimed Sulphur, or
Flower of Sulphur, hath exactly the same properties as Sulphur that has
never been sublimed.
If Sulphur be exposed to a brisk heat in the open air, it takes fire,
burns, and is wholly consumed. This deflagration of Sulphur is the
only means we have of decomposing it, in order to obtain its Acid in
purity. The Phlogiston is destroyed by the flame, and the Acid exhales
in vapours: these vapours collected have all the properties of the
Vitriolic Acid, and differ from it only as they still retain some
portion of the Phlogiston; which, however, soon quits them of its own
accord, if the free access of the common air be not precluded.
The portion of Phlogiston retained by the Acid of Sulphur is much more
considerable when that mineral is burnt gradually and slowly: in that
case the vapours which rise from it have such a penetrating odour,
that they instantaneously suffocate any person who draws in a certain
quantity of them with his breath. These vapours constitute what is
called the _Volatile Spirit of Sulphur_. There is reason to think this
portion of Phlogiston which the Acid retains is combined therewith in a
manner different from that in which these two are united in the Sulphur
itself; for, as has just been observed, nothing but actual burning is
capable of separating the Vitriolic Acid and the Phlogiston, which by
their union form Sulphur; whereas in the Volatile Spirit of Sulphur
they separate spontaneously when exposed to the open air; that is, the
Phlogiston flies off and leaves the Acid, which then becomes in every
respect similar to the Vitriolic Acid.
That the Volatile Spirit of Sulphur is a compound, as we have asserted
it to be, appears evidently from hence, that whenever the Vitriolic
Acid touches any substance containing the Phlogiston, provided that
Phlogiston be disengaged or opened to a certain degree, a Volatile
Spirit of Sulphur is infallibly and immediately generated. This Spirit
hath all the properties of Acids, but considerably weakened, and of
course less perceptible. It unites with absorbent earths or fixed
Alkalis; and with them forms Neutral Salts; but when combined therewith
it may be separated from them by the Vitriolic Acid, and indeed by
any of the mineral Acids, because its affinities are weaker. Sulphur
hath the property of uniting with absorbent earths, but not near so
intimately as with fixed Alkalis.
If equal parts of Sulphur and an Alkali be melted together, they
incorporate with each other; and from their conjunction proceeds a
compound of a most unpleasant smell, much like that of rotten eggs,
and of a red colour nearly resembling that of an animal liver, which
has occasioned it to bear the name of _Hepar Sulphuris_, or _Liver of
Sulphur_.
In this composition the fixed Alkali communicates to the Sulphur the
property of dissolving in water: and hence it comes that Liver of
Sulphur may be made as well when the Alkali is dissolved by water into
a fluid, as when it is fused by the action of fire.
Sulphur has less affinity than any Acid with the fixed Alkalis: and
therefore Liver of Sulphur may be decompounded by any Acid whatever;
which will unite with the fixed Alkali, form therewith a Neutral Salt,
and separate the Sulphur.
If Liver of Sulphur be dissolved in water, and an Acid poured thereon,
the liquor, which was transparent before, instantly turns to an opaque
white; because the Sulphur, being forced to quit its union with the
Alkali, loses at the same time the property of dissolving in water, and
appears again in its own opaque form. The liquor thus made white by the
Sulphur is called _Milk of Sulphur_.
If this liquor be suffered to stand still for some time, the particles
of Sulphur, now most minutely divided, gradually approach each other,
unite, and fall insensibly to the bottom of the vessel; and then the
liquor recovers its transparency. The Sulphur thus deposited on the
bottom of the vessel is called the _Magistery_ or _Precipitate of
Sulphur_. The names of Magistery and Precipitate are also given to all
substances whatever, that are separated from another by this method;
which is the reason that we use the expression of precipitating one
substance by another, to signify the separating one of them by means of
the other.
SECTION II.
_Of the_ NITROUS ACID.
It is not certainly known what constitutes the difference between the
Nitrous Acid and the Vitriolic Acid, with regard to the constituent
principles of each. The most probable opinion is, that the Nitrous Acid
is no other than the Vitriolic Acid combined with a certain quantity of
Phlogiston by the means of putrefaction. If it be so, the Phlogiston
must be united with the Universal Acid in another manner than it is in
sulphur, and in its volatile spirit: for the Nitrous Acid differs from
them both in its properties. What gives ground for this opinion is,
that the Nitrous Acid is never found but in earths and stones which
have been impregnated with matters subject to putrefaction, and which
therefore must contain the Phlogiston. For it is necessary just to
observe here, though it be not yet proper to enter particularly into
the subject, that all substances susceptible of putrefaction really
contain the Phlogiston.
The Nitrous Acid combined with certain absorbent earths, such as chalk,
marle, boles, forms Neutral Salts which do not crystallize; and which,
after being dried, run in the air _per deliquium_.
All those Neutral Salts which consist of the Nitrous Acid joined to an
earth, may be decomposed by a fixed Alkali, with which the Acid unites,
and deserts the earth; and from this union of the Nitrous Acid with a
fixed Alkali results a new Neutral Salt which is called _Nitre_, or
_Salt-peter_. This latter name signifies the _Salt of Stone_; and,
in fact, Nitre is extracted from the stones and plaster, in which it
forms, by boiling them in water saturated with a fixed Alkali.
Nitre shoots in long crystals adhering sideways to each other; it has
a saltish taste, which produces a sensation of cold on the tongue.
This Salt easily dissolves in water; which, when boiling hot, takes up
still a greater quantity thereof.
It flows with a pretty moderate degree of heat, and continues fixed
therein; but being urged by a brisk fire, and in the open air, it lets
go some part of its Acid, and indeed flies off itself in part.
The most remarkable property of Nitre, and that which characterizes it,
is its fulmination or explosion; the nature of which is as follows:
When Nitre touches any substance containing a Phlogiston, and actually
ignited, that is, actually on fire, it bursts out into a flame, burns,
and is decompounded with much noise.
In this deflagration the Acid is dissipated, and totally separated from
the Alkali, which now remains by itself.
Indeed the Acid, at least the greatest part of it, is by this means
quite destroyed. The Alkali which is left when Nitre is decompounded
by deflagration, is called in general _Fixed Nitre_, and, more
particularly, Nitre fixed by such and such a substance as was used
in the operation. But if Nitre be deflagrated with an inflammable
substance containing the vitriolic Acid, as sulphur, for instance,
the fixed Salt produced by the deflagration is not a pure Alkali, but
retains a good deal of the vitriolic Acid, and, by combining therewith,
hath now formed a neutral Salt.
Hitherto Chymists have been at a loss for the reason why Nitre flames,
and is decompounded in the manner above-mentioned, when it comes in
contact with a Phlogiston properly circumstanced. For my part, I
conjecture it to be for the same reason that vitriolated tartar is
also decompounded by the addition of a Phlogiston; _viz._ the Nitrous
Acid, having a greater affinity with the Phlogiston than with the
fixed Alkali, naturally quits the latter to join with the former, and
so produces a kind of sulphur, differing probably from the common
sulphur, formed by the vitriolic Acid, in that it is combustible to
such a degree, as to take fire and be consumed in the very moment of
its production; so that it is impossible to prevent its being thus
destroyed, and consequently impossible to save it. In support of this
opinion let it be considered, that the concurrence of the Phlogiston
is absolutely necessary to produce this deflagration, and that the
matter of pure fire is altogether incapable of effecting it: for though
Nitre be exposed to the most violent degree of fire, even that in the
focus of the most powerful burning-glass, it will not flame; nor will
that effect ever happen till the Nitre be brought into contact with a
Phlogiston properly so called, that is, the matter of fire existing
as a principle of some body; and it is moreover necessary that this
Phlogiston be actually on fire, and agitated with the igneous motion,
or else that the Nitre itself be red hot, and so penetrated with fire
as to kindle any inflammable matter that touches it.
This experiment, among others, helps to shew the distinction that ought
to be made between pure elementary fire, and fire become a principle of
bodies, to which we have given the name of Phlogiston.
Before we leave this subject, we shall observe, that Nitre deflagrates
only with such substances as contain the Phlogiston in its simplest and
purest form; such as charcoal, sulphur, and the metalline substances;
and that, though it will not deflagrate without the addition of some
combustible matter, it is nevertheless the only known body that will
burn, and make other combustibles burn with it, in close vessels,
without the admission of fresh air.
The Nitrous Acid hath not so great an affinity with earths and Alkalis
as the vitriolic Acid hath with the same substances; whence it follows
that the vitriolic Acid decomposes all neutral salts arising from
a combination of the Nitrous Acid with an earth or an Alkali. The
vitriolic Acids expells the Nitrous Acid, unites with the substance
which served it for a basis, and therewith forms a neutral salt, which
is an Alum, a Selenites, or a vitriolated Tartar, according to the
nature of that basis.
The Nitrous Acid, when thus separated from its basis by the vitriolic
Acid, is named _Spirit of Nitre_, or _Aqua Fortis_. If it be
dephlegmated, or contain but little superfluous water, it exhales in
reddish vapours; these vapours, being condensed and collected, form
a liquor of a brownish yellow, that incessantly emits vapours of the
same colour, and of a pungent disagreeable smell. These characters have
procured it the names of _Smoaking Spirit of Nitre_, and _Yellow Aqua
Fortis_. This property in the Nitrous Acid, of exhaling in vapours,
shews it to be less fixed than the vitriolic Acid; for the latter,
though ever so thoroughly dephlegmated, never yields any vapours, nor
has it any smell.
SECTION III.
_Of the_ ACID OF SEA-SALT.
The Acid of Sea-salt is so called because it is in fact obtained from
such Sea-salt as is used in our kitchens. It is not certainly known
in what this Acid differs from the vitriolic and the nitrous, with
regard to its constituent parts. Several of the ablest Chymists, such
as Becher and Stahl, are of opinion that the Marine Acid is no other
than the Universal Acid united to a particular principle which they
call a Mercurial Earth. Concerning this earth we shall have occasion
to say more, when we come to treat of metallic substances: but in the
mean time it must be owned, that the truth of this opinion is so far
from being proved by a sufficient number of experiments, that the
very existence of such a mercurial earth is not yet well established;
and therefore, that we may not exceed the bounds of our knowledge,
we shall content ourselves with delivering here the properties which
characterize the Acid in question, and by which it is distinguished
from the two others considered above.
When it is combined with absorbent earths, such as lime and chalk,
it forms a neutral salt that does not crystallize, and, when dried,
attracts the moisture of the air. If the absorbent earth be not fully
saturated with the Marine Acid, the salt thereby formed has the
properties of a fixed Alkali: and this is what made us say, when we
were on the subject of those salts, that they might be imitated by
combining an earth with an Acid. The Marine Acid, like the rest, hath
not so great an affinity with earths as with fixed Alkalis.
When it is combined with the latter, it forms a neutral salt which
shoots into cubical crystals. This salt is inclined to grow moist in
the air, and is consequently one of those which water dissolves in
equal quantities, at least as to sense, whether it be boiling hot or
quite cold.
The affinity of this Acid with Alkalis and absorbent Earths is not
so great as that of the vitriolic and nitrous Acids with the same
substances: whence it follows, that, when combined therewith, it may be
separated from them by either of those Acids.
The Acid of Sea-salt, thus disengaged from the substance which served
it for a basis, is called _Spirit of Salt_. When it contains but little
phlegm it is of a lemon colour, and continually emits many white, very
dense, and very elastic vapours; on which account it is named the
_Smoaking Spirit of Salt_. Its smell is not disagreeable, nor much
unlike that of saffron; but extremely quick and suffocating when it
smokes.
The Acid of Sea-salt, like the other two, seems to have a greater
affinity with the Phlogiston, than with fixed Alkalis. We are led
to this opinion by a very curious operation, which gives ground to
think that Sea-salt may be decomposed by the proper application of a
substance containing the Phlogiston.
From the Marine Acid combined with a Phlogiston results a kind
of Sulphur, differing from the common sort in many respects; but
particularly in this property, that it takes fire of itself upon
being exposed to the open air. This combination is called _English
Phosphorus_, _Phosphorus of Urine_, because it is generally prepared
from urine; or, only _Phosphorus_.
This combination of the Marine Acid with a Phlogiston is not easily
effected; because it requires a difficult operation in appropriated
vessels. For these reasons it does not always succeed; and Phosphorus
is so scarce and dear, that hitherto Chymists have not been able to
make on it the experiments necessary to discover all its properties. If
Phosphorus be suffered to burn away in the air, a small quantity of an
acid liquor may be obtained from it, which seems to be spirit of salt,
but either altered, or combined with some adventitious matter; for it
has several properties that are not to be found in the pure Marine
Acid; such as, leaving a fixed fusible substance behind it when exposed
to a strong fire, and being easily combined with the Phlogiston so as
to reproduce a Phosphorus.
Phosphorus resembles sulphur in several of its properties: it is
soluble in oils; it melts with a gentle heat; it is very combustible;
it burns without producing soot; and its flame is vivid and bluish.
From what has been said of the union of the Acid of Sea-salt with a
fixed Alkali, and of the neutral salt resulting therefrom, it may
be concluded that this neutral salt is no other than the common
kitchen-salt. But it must be observed, that the fixed Alkali, which is
the natural basis of the common salt obtained from sea-water, is of a
sort somewhat differing from fixed Alkalis in general, and hath certain
properties peculiar to itself. For,
1. The basis of Sea-salt differs from other fixed Alkalis in this, that
it crystallizes like a neutral salt.
2. It does not grow moist in the air; on the contrary, when exposed
to the air, it loses part of the water that united with it in
crystallization, by which means its crystals lose their transparency,
become, as it were, mealy, and fall into a fine flour.
3. When combined with the vitriolic Acid to the point of saturation,
it forms a neutral salt differing from vitriolated tartar, first,
in the figure of its crystals, which are oblong six-sided solids;
secondly, in its quantity of water, which in crystallization unites
therewith in a much greater proportion than with vitriolated tartar;
whence it follows, that this salt dissolves in water more readily than
vitriolated tartar; thirdly, in that it flows with a very moderate
degree of heat, whereas vitriolated tartar requires a very fierce one.
If the Acid of Sea-salt be separated from its basis by means of the
vitriolic Acid, it is easy to see that, when the operation is finished,
the salt we have been speaking of must be the result. A famous Chymist,
named Glauber, was the first who extracted the Spirit of Salt in
this manner, examined the neutral salt resulting from his process,
and, finding it to have some singular properties, called it his _Sal
mirabile_, or wonderful Salt: on this account it is still called
Glauber's _Sal mirabile_, or plainly _Glauber's Salt_.
4. When the basis of Sea-salt is combined with the nitrous Acid to
the point of saturation, there results a neutral salt, or a sort of
nitre, differing from the common nitre, first, in that it attracts
the moisture of the air pretty strongly; and this makes it difficult
to crystallize; secondly, in the figure of its crystals, which are
parallelopipeds; and this has procured it the name of _Quadrangular
Nitre_.
Common salt, or the neutral salt formed by combining the Marine Acid
with this particular sort of fixed Alkali, has a taste well known to
every body. The figure of its crystals is exactly cubical. It grows
moist in the air, and, when exposed to the fire, it bursts, before it
melts, into many little fragments, with a crackling noise; which is
called the _Decrepitation_ of Sea-salt.
That neutral salt mentioned above, which is formed by combining the
Marine Acid with a common fixed Alkali, and called _Sal febrifugum
Sylvii_, hath also this property.
India furnishes us with a saline substance, known by the name of
_Borax_, which flows very easily, and then takes the form of glass. It
is of great use in facilitating the fusion of metallic substances. It
possesses some of the properties of fixed Alkalis, which has induced
certain Chymists to represent it, through mistake, as a pure fixed
Alkali.
By mixing borax with the vitriolic Acid, Mr. Homberg obtained from
it a salt, which sublimes in a certain degree of heat, whenever such
a mixture is made. This salt has very singular properties; but its
nature is not yet thoroughly understood. It dissolves in water with
great difficulty; it is not volatile, though it rises by sublimation
from the borax. According to Mr. Rouelle's observation, it rises then
only by means of the water which carries it up: for, when once made,
it abides the fiercest fire, flows and vitrifies just as borax does:
provided care be taken to free it previously from moisture by drying
it properly. Mr. Homberg called it _Sedative Salt_, on account of its
medical effects. The sedative salt hath the appearance, and some of the
properties, of a neutral salt; for it shoots into crystals, and does
not change the colour of violets; but it acts the part of an Acid with
regard to Alkalis, uniting with them to the point of saturation, and
thereby forming a true neutral salt. It also acts, like the Acid of
vitriol on all neutral salts; that is, it discharges the Acid of such
as have not the vitriolic Acid in their composition.
Since Mr. Homberg's time it hath been discovered, that a sedative salt
may be made either with the nitrous or with the marine Acid; and that
sublimation is not necessary to extract it from the borax, but that it
may be obtained by crystallization only. For this latter discovery we
are indebted to Mr. Geoffry, as we are to Mr. Lemery for the former.
Since that time M. Baron d'Henouville, an able Chymist, hath shewn that
a sedative salt may be obtained by the means of vegetable Acids; and
hath lately demonstrated, in some excellent papers published in the
collection of Memoirs written by the correspondents of the Academy of
Sciences, that the sedative salt exists actually and perfectly in the
borax, and that it is not produced by mixing Acids with that saline
substance, as it seems all the Chymists before him imagined. This he
proves convincingly from his analysis of borax, (which thereby appears
to be nothing else but the sedative salt united with that fixed Alkali
which is the basis of Sea-salt) and from his regenerating the same
borax by uniting together that Alkali and the sedative salt: a proof
the most complete that can possibly be produced in natural philosophy,
and equivalent to demonstration itself.
In order to finish what remains to be said upon the several sorts of
saline substances, we should now speak of the Acids obtained from
vegetables and animals, and also of the volatile Alkalis: but, seeing
these saline substances differ from those of which we have already
treated, only as they are variously altered by the unions they have
contracted with certain principles of vegetables and animals, of which
nothing has been yet said, it is proper to defer being particular
concerning them, till we have explained those principles.
CHAP. V.
_Of_ LIME.
Any substance whatever, that has been roasted a considerable time in
a strong fire without melting, is commonly called a _Calx_. Stones
and metals are the principal subjects that have the property of being
converted into _Calces_. We shall treat of Metalline _Calces_ in a
subsequent chapter, and in this confine ourselves to the _Calx_ of
_Stone_, known by the name of _Lime_.
In treating of earths in general we observed that they may be divided
into two principal kinds; one of which actually and properly flows when
exposed to the action of fire, and turns to glass; whence it is called
a _fusible_ or _vitrifiable_ earth; the other resists the utmost force
of fire, and is therefore said to be an _unfusible_ or _unvitrifiable_
earth. The latter is also not uncommonly called _calcinable_ earth;
though sundry sorts of unfusible earths are incapable of acquiring by
the action of fire all the qualities of _calcined_ earth, or _Lime_
properly so called: such earths are particularly distinguished by the
denomination of _refractory_ earths.
As the different sorts of stones are nothing more than compounds of
different earths, they have the same properties with the earths of
which they are composed, and may, like them, be divided into fusible
or vitrifiable, and unfusible or calcinable. The fusible stones are
generally denoted by the name of _Flints_; the calcinable stones,
again, are the several sorts of marbles, cretaceous stones, those
commonly called free-stones, _&c._ some of which, as they make the best
Lime, are, by way of eminence, called _Lime-stones_. Sea-shells, also,
and stones that abound with fossile shells, are capable of being burnt
to Lime.
All these substances, being exposed, for a longer or shorter time, as
the nature of each requires, to the violent action of fire, are said to
be _calcined_. By calcination they lose a considerable part of their
weight, acquire a white colour, and become friable though ever so solid
before; as, for instance, the very hardest marbles. These substances,
when thus calcined, take the name of _Quick Lime_.
Water penetrates Quick Lime, and rushes into it with vast activity.
If a lump of newly calcined Lime be thrown into water, it instantly
excites almost as great a noise, ebullition, and smoke, as would be
produced by a piece of red-hot iron; with such a degree of heat too,
that, if the Lime be in due proportion to the water, it will set fire
to combustible bodies; as hath unfortunately happened to vessels laden
with Quick Lime, on their springing a small leak.
As soon as Quick Lime is put into water, it swells, and falls asunder
into an infinite number of minute particles: in a word, it is in a
manner dissolved by the water, which forms therewith a sort of white
paste called _Slacked Lime_.
If the quantity of water be considerable enough for the Lime to form
with it a white liquor, this liquor is called _Lac Calcis_; which,
being left some time to settle, grows clear and transparent, the Lime
which was suspended therein, and occasioned its opacity, subsiding to
the bottom of the vessel. Then there forms on the surface of the liquor
a crystalline pellicle, somewhat opaque and dark-coloured, which being
skimmed off is reproduced from time to time. This matter is called
_Cremor Calcis_.
Slacked Lime gradually grows dry, and takes the form of a solid body,
but full of cracks and destitute of firmness. The event is different
when you mix it up, while yet a paste, with a certain quantity of
uncalcined stony matter, such as sand, for example: then it takes
the name of _Mortar_, and gradually acquires, as it grows drier and
older, a hardness equal to that of the best stones. This is a very
singular property of Lime, nor is it easy to account for it: but it is
a beneficial one; for every body knows the use of Mortar in building.
Quick Lime attracts the moisture of the air, in the same manner as
concentrated acids, and dry fixed alkalis; but not in such quantities
as to render it fluid: it only falls into extremely small particles,
takes the form of a fine powder, and the title of _Lime slacked in the
air_.
Lime once slacked, however dry it may afterwards appear, always
retains a large portion of the water it had imbibed; which cannot be
separated from it again but by means of a violent calcination. Being so
recalcined it returns to be Quick Lime, recovering all its properties.
Besides this great affinity of Quick Lime with water, which discovers
a saline character, it has several other saline properties, to be
afterwards examined, much resembling those of fixed alkalis. In
Chymistry it acts very nearly as those salts do, and may be considered
as holding the middle rank between a pure absorbent earth and a fixed
alkali: and this hath induced many Chymists to think that Lime contains
a true salt, to which all the properties it possesses in common with
salts may be attributed.
But as the chymical examination of this subject hath long been
neglected, the existence of a saline substance in Lime hath been long
doubtful. Mr. du Fay, author of some excellent chymical experiments,
was one of the first who obtained a salt from Lime, by lixiviating
it with a great deal of water, which he afterwards evaporated. But
the quantity of salt he obtained by that means was very small; nor
was it of an alkaline nature, as one would think it should have been,
considering the properties of Lime. Mr. du Fay did not carry his
experiments on this subject any further, probably for want of time; nor
did he determine of what nature the salt was.
Mr. Malouin had the curiosity to examine this salt of Lime, and
soon found that it was nothing else but what was above called
_Cremor Calcis_. He found, moreover, that, by mixing a fixed alkali
with lime-water, a vitriolated tartar was formed; that, by mixing
therewith an alkali like the basis of sea-salt, a Glauber's salt was
produced; and, lastly, by combining lime with a substance abounding
in phlogiston, he obtained a true sulphur. These very ingenious
experiments prove to a demonstration, that the vitriolic acid
constitutes the salt of Lime: for, as hath been shewn, no other acid is
capable of forming such combinations. On the other hand, Mr. Malouin,
having forced the vitriolic acid of this salt to combine with a
phlogiston, found its basis to be earthy, and analogous to that of the
selenites: whence he concluded, that the salt of Lime is a true neutral
salt, of the same kind as the selenites. Mr. Malouin tells us he found
several other salts in Lime. But as none of them was a fixed alkali,
and as all the saline properties of Lime have an affinity with those of
that kind of salt, there is great reason to think that all those salts
are foreign to Lime, and that their union with it is merely accidental.
I myself have made several experiments in order to get some insight
into the saline nature of Lime, and shall here produce the result
with all possible conciseness. I took several stones of different
kinds, some of which produced by calcination a very strong Lime, and
others but a very weak one. These I impregnated with different saline
substances, acids, alkalis, and neutrals, and then exposed them all
to the same degree of fire, which was a pretty strong one, and long
enough continued to have made very good Lime of stones the most
difficult to calcine. The consequence was, that, in the first place,
those stones which naturally made but a weak Lime were not, by this
process, converted into a stronger Lime; and, moreover, that none of
these stones, even such as would naturally have produced the most
active Lime, had acquired the properties of Lime. These experiments I
varied many ways, employing different proportions of saline matters,
and almost every possible degree of fire, and constantly observed,
after calcination, that all those stones were so much the farther from
the nature of Lime, as they had been combined with larger doses of
salts. Among those which were impregnated with the greatest proportion
of salts, and had suffered the greatest violence of fire, I observed
some that had begun to flow, and were in a manner vitrified. Now, as
the same subject cannot be, at one and the same time, in the state
of glass and of Lime too; as a body cannot approach to one of these
states but in proportion as it recedes from the other; and as salts in
general dispose those bodies to fusion and vitrification which are in
themselves the most averse to either, I concluded from my experiments,
that the saline substances I used, had, by acting as fluxes upon the
stones, prevented their calcination; that consequently we may suspect
there is no saline matter in the composition of Lime, as Lime; and that
Lime does not owe its saline and alkaline properties to any salt; or at
least that, if it does owe those properties to a salt, such salt must
be naturally and originally combined with the matter of the stone in
so just a proportion, that it is impossible to increase the quantity
thereof without prejudicing the Lime, and depriving it in some measure
of its virtue. This theory agrees perfectly with the illustrious
Stahl's opinion; for he thinks, as we observed in discoursing of salts
in general, that every saline substance is but an earth combined in
a certain manner with water. This notion he applies to Lime, and
says, that fire only subtilizes and attenuates the earthy matter, and
thereby renders it capable of uniting with water in such a manner, that
the result of their combination shall be a substance having saline
properties; and that Lime accordingly never acquires these properties
till it be combined with water.
I have dwelt longer on the Salt of Lime than I shall on any other
particular; because the subject, though in itself of great importance,
has hitherto been but little attended to, and because the experiments
here recited are entirely new.
Lime unites with all acids, and in conjunction with them exhibits
various phenomena.
The vitriolic acid poured upon Lime dissolves it with effervescence and
heat. From this mixture there exhales a great quantity of vapours, in
smell and colour perfectly like those of sea-salt; from which, however,
they are found to be very different when collected into a liquor. From
this combination of the vitriolic acid with Lime arises a neutral salt,
which shoots into crystals, and is of the same kind with the selenetic
salt obtained from Lime by Mr. Malouin.
The nitrous acid poured upon Lime dissolves it in like manner with
effervescence and heat: but the solution is transparent, and therein
differs from the former, which is opaque. From this mixture there
arises a neutral salt, which does not crystallize, and has withal
the very singular property of being volatile, and rising wholly by
distillation in a liquid form. This phenomenon is so much the more
remarkable, as Lime, the basis of this salt, is one of the most fixed
bodies known in Chymistry.
With the acid of sea-salt Lime forms also a singular sort of salt,
which greedily imbibes the moisture of the air. We shall have occasion
to take further notice of it in another place.
These experiments made on Lime with acids are likewise quite new. We
are indebted for them to Mr. Du Hamel of the Academy of Sciences, whose
admirable Memoirs on several subjects shew his extensive knowledge in
all parts of Natural Philosophy.
Lime applied to fixed alkalis adds considerably to their caustic
quality, and makes them more penetrating and active. An alkaline
lixivium in which Lime hath been boiled, being evaporated to dryness,
forms a very caustic substance, which flows in the fire much more
easily, attracts and retains moisture much more strongly, than fixed
alkalis that have not been so treated. An alkali thus acuated by Lime
is called the _Caustic Stone_, or _Potential Cautery_; because it is
employed by surgeons to produce eschars on the skin and cauterize it.
CHAP. VI.
_Of Metallic Substances in general._
Metallic Substances are heavy, glittering, opaque, fusible bodies. They
consist chiefly of a vitrifiable earth united with the phlogiston.
Several Chymists insist on a third principle in these bodies, and have
given it the name of _Mercurial Earth_; which, according to Becher and
Stahl, is the very same that being combined with the vitriolic acid
forms and characterizes the acid of sea-salt. The existence of this
principle hath not yet been demonstrated by any decisive experiment;
but we shall shew that there are pretty strong reasons for admitting it.
We shall begin with mentioning the experiments which prove Metallic
Substances to consist of a vitrifiable earth united with the
phlogiston. The first is this: if they be calcined in such a manner
as to have no communication with any inflammable matter, they will be
spoiled of all their properties, and reduced to an earth or calx, that
has neither the splendour nor the ductility of a metal, and in a strong
fire turns to an actual glass, instead of flowing like a metal.
The second is, that the calx or the glass resulting from a metal thus
decomposed, recovers all its metalline properties by being fused in
immediate contact with an inflammable substance, capable of restoring
the phlogiston of which calcination had deprived it.
On this occasion we must observe, that Chymists have not yet been
able, by adding the phlogiston, to give the properties of metals to
all sorts of vitrifiable earths indiscriminately; but to such only as
originally made a part of some metallic body. For example, a compound
cannot be made with the phlogiston and sand that shall have the least
resemblance of a metal: and this is what seems to point out the reality
of a third principle, as necessary to form the metalline combination.
This principle may probably remain united with the vitrifiable earth
of a metallic substance, when reduced to a glass; whence it follows,
that such vitrified metals require only the addition of a phlogiston to
enable them to appear again in their pristine form.
It may be inferred from another experiment, that the calx and the glass
of a metal are not its pure vitrifiable earth, properly so called: for
by repeated or long-continued calcinations, such a calx or glass may
be rendered incapable of ever resuming the metalline form, in whatever
manner the phlogiston be afterwards applied to it; so that by this
means it is brought into the condition of a pure vitrifiable earth,
absolutely free from any mixture. Those Chymists who patronize the
Mercurial earth, produce many other proofs of the existence of that
principle in Metallic Substances; but they would be misplaced in an
elementary treatise like this.
When by adding the phlogiston to a metallic glass we restore it to the
form of a metal, we are said to _reduce_, _resuscitate_, or _revivify_
that metal.
Metallic Substances are of different kinds, and are divided into
_Metals_ and _Semi-metals_.
Those are called Metals which, besides their metalline splendour
and appearance, are also malleable; that is, have the property of
stretching under the hammer, and by that means of being wrought into
different forms without breaking.
Those which have only the metalline splendour and appearance, without
malleability, are called Semi-metals.
Metals are also further subdivided into two sorts; _viz._ _Perfect_ and
_Imperfect_ Metals.
The Perfect Metals are those which suffer no damage or change whatever
by the most violent and most lasting action of fire.
The Imperfect Metals are those which by the force of fire, may be
deprived of their phlogiston, and consequently of their metalline form.
When but a moderate degree of fire is employed to deprive a Metal of
its phlogiston, the metal is said to be _calcined_; and then it appears
in the form of a powdered earth, which is called a _Calx_: and this
metalline calx being exposed to a more violent degree of fire melts and
turns to glass.
Metallic Substances have an affinity with acids: but not equally with
all; that is, every Metallic Substance is not capable of uniting and
joining with every acid.
When an acid unites with a Metallic Substance there commonly arises
an ebullition, attended with a kind of hissing noise and fuming
exhalations. By degrees, as the union becomes more perfect, the
particles of the metal combining with the acid become invisible: this
is termed _Dissolution_; and when a metalline mass thus appears in an
acid, the metal is said to be _dissolved_ by that acid. It is proper
to observe, that acids act upon Metalline Substances, in one respect,
just as they do upon alkalis and absorbent earths: for an acid cannot
take up above such a certain proportion thereof as is sufficient to
saturate it, to destroy several of its properties, and weaken others.
For example, when an acid is combined with a metal to the point of
saturation, it loses its taste, does not turn the blue colour of a
vegetable red, and its affinity with water is considerably impaired. On
the other hand, Metalline Substances, which when pure are incapable of
uniting with water, by being joined with an acid acquire the property
of dissolving in water. These combinations of Metalline Substances with
acids form different sorts of neutral salts; some of which have the
property of shooting into crystals, while others have it not: most of
them, when thoroughly dried, attract the moisture of the air.
The affinity which Metalline Substances have with acids is less than
that which absorbent earths and fixed alkalis have with the same
acids; so that all metalline salts may be decompounded by one of these
substances, which will unite with the acid, and precipitate the metal.
Metalline Substances thus separated from an acid solvent are called
_Magisteries_ and _Precipitates_ of metals. None of these precipitates,
except those of the perfect metals, retain the metalline form: most of
their phlogiston hath been destroyed by the solution and precipitation,
and must be restored before they can recover their properties. In
short, they are nearly in the same state with Metalline Substances
deprived of their phlogiston by calcination; and accordingly such a
precipitate is called a _Calx_.
A metalline calx prepared in this manner loses a greater or a less
portion of its phlogiston, the more or less effectually and thoroughly
the Metalline Substance, of which it made a part, was dissolved by the
acid.
Metallic Substances have affinities with each other which differ
according to their different kinds: but this is not universal; for some
of them are incapable of any sort of union with some others.
It must be observed, that Metallic Substances will not unite, except
they be both in a similar state; that is, both in a Metalline form, or
both in the form of a Glass; for a Metalline Substance retaining its
phlogiston cannot contract an union with any metallic glass, even its
own.
CHAP. VII.
_Of_ METALS.
There are six Metals, of which two are Perfect and four Imperfect. The
perfect Metals are Gold and Silver; the others are Copper, Tin, Lead,
and Iron. Some Chymists admit a seventh Metal, to wit, Quick-silver:
but as it is not malleable, it has been generally considered as a
metallic body of a particular kind. We shall soon have occasion to
examine it more minutely.
The ancient Chymists, or rather the Alchymists, who fancied a certain
relation or analogy between Metals and the Heavenly Bodies, bestowed
on the seven Metals, reckoning Quick-silver one of them, the names of
the seven Planets of the Ancients, according to the affinity which
they imagined they observed between those several bodies. Thus Gold
was called _Sol_, Silver _Luna_, Copper _Venus_, Tin _Jupiter_, Lead
_Saturn_, Iron _Mars_, and Quick-silver _Mercury_. Though these names
were assigned for reasons merely chimerical, yet they still keep their
ground; so that it is not uncommon to find the Metals called by the
names, and denoted by the characters, of the Planets, in the writings
even of the best Chymists. Metals are the heaviest bodies known in
nature.
SECTION I.
_Of_ GOLD.
Gold is the heaviest of all Metals. The arts of wire-drawing and
gold-beating shew its wonderful ductility. The greatest violence
of fire is not able to produce any alteration in it. Indeed Mr.
Homberg, a famous Chymist, pretended that he had made this metal fume,
and even vitrified it, by exposing it to the focus of one of the
best burning-glasses, known by the name of the Lens of the _Palais
Royal_: but, there are very good reasons for calling in question the
experiments he made on this occasion, or rather for thinking that he
was quite mistaken. For,
1. No man hath since been able to vitrify Gold, though several good
Experimenters have assiduously tried to effect it, by exposing it to
the focus of the same lens, and of other burning-glasses still stronger.
2. It hath been observed, that though Gold, when exposed to the focus
of those glasses, did indeed emit some vapours and decrease in weight;
yet, those vapours being carefully collected on a piece of paper,
proved to be true Gold, in no degree vitrified, and which consequently
had suffered no change but that of being carried away by the violence
of the heat, its nature not being in the least altered.
3. The small portion of vitrified matter, which was formed on the arm
that supported the Gold in Mr. Homberg's experiment, may have come
either from the arm itself, or rather from some heterogeneous particles
contained in the Gold; for it is almost impossible to have it perfectly
pure.
4. Neither Mr. Homberg, nor any that have repeated his experiment, ever
reduced this pretended glass of Gold by restoring its Phlogiston, as is
done with other metallic glasses.
5. To render the experiment decisive, the whole mass of Gold employed
ought to have been vitrified; which was not the case.
Nevertheless, I do not pretend that this metal is in its own nature
absolutely indestructible, and unvitrifiable: but there is reason to
think that no body hath hitherto found the means of producing those
effects on it, probably for want of a sufficient degree of fire; at
least the point is very doubtful.
Gold cannot be dissolved by any pure acid: but if the acid of nitre be
mixed with the acid of sea-salt, there results a compound acid liquor,
with which it has so great an affinity that it is capable of being
perfectly dissolved thereby. The Chymists have called this solvent
_Aqua Regis_, on account of its being the only acid that can dissolve
Gold, which they consider as the King of Metals. The solution of gold
is of a beautiful orange colour.
If Gold dissolved in _aqua regis_ be precipitated by an alkali or an
absorbent earth, the precipitate gently dried, and then exposed to a
certain degree of heat, is instantly dispersed into the air, with a
most violent explosion and noise: Gold thus precipitated is therefore
called _Aurum Fulminans_. But if the precipitated Gold be carefully
washed in plenty of water, so as to clear it of all the adhering saline
particles, it will not fulminate, but may be melted in a crucible
without any additament, and will then appear in its usual form. The
acid of vitriol being poured on _aurum fulminans_ likewise deprives it
of its fulminating quality.
Gold does not begin to flow till it be red-hot like a live coal. Though
it be the most malleable and most ductile of all metals, it has the
singular property of losing its ductility more easily than any of them:
even the fumes of charcoal are sufficient to deprive it thereof, if
they come in contact with it while it is in fusion.
The malleability of this metal, and indeed of all the rest, is also
considerably diminished by exposing it suddenly to cold when it is
red-hot; for example, by quenching it in water, or even barely exposing
it to the cold air.
The way to restore ductility to gold, when lost by its coming in
contact with the vapour of coals, and in general to any metal rendered
less malleable by being suddenly cooled, is to heat it again, to keep
it red hot a considerable time, and then to let it cool very slowly
and gradually; this operation frequently repeated will by degrees much
increase the malleability of a metal.
Pure sulphur hath no effect on Gold; but being combined with an alkali
into a _hepar sulphuris_, it unites therewith very readily. Nay, so
intimate is their union, that the Gold, by means thereof, becomes
soluble in water; and this new compound of Gold and liver of sulphur,
being dissolved in water, will pass through the pores of brown paper
without suffering any decomposition; which does not happen, at least in
such a manifest degree, to other metallic substances dissolved by liver
of sulphur.
_Aurum fulminans_, mixed and melted with flower of sulphur, loses its
fulminating quality: which arises from hence, that on this occasion
the sulphur burns, and its acid, which is the same with the vitriolic,
being thereby set at liberty becomes capable of acting upon the Gold as
a vitriolic acid would; which, as was said above, deprives the Gold of
its fulminating quality.