It is not very probable that Dioscorides, Pliny, and others who lived
nearly about the same time, were acquainted with sal-ammoniac, or
mentioned it in their works; for no part of mineralogy was then so
defective as that which is the most important, and which treats of
salts. The art of lixiviating earths and causing saline solutions to
crystallize was then so little known, that, instead of green vitriol,
vitriolic minerals, however impure, were employed in making ink,
dye-liquors, and other things. Places for boiling vitriol were not
then established, and therefore Pliny beheld with wonder blue vitriol,
which in his time was made only in Spain, as a thing singular in its
kind, or which had not its like. On this account those salts only were
known which occur in a native state, or which crystallize as it were
of themselves, without any artificial preparation, as is the case with
bay salt. But that neutral salt, formed of muriatic acid and ammonia,
occurs very seldom in a native state, and almost exclusively among the
productions of volcanoes. I do not, however, suppose that this volcanic
sal-ammoniac was the first known, but that it was first considered
to be sal-ammoniac after that salt had been long obtained by another
method, and long used.
But even if it should be believed that our sal-ammoniac was known
to the ancients, how are we to discover it with certainty in their
writings? This salt has little or nothing by which these writers could
characterize it. Neither its external form nor taste is so striking
that it could be described by them with sufficient precision. The use
of it also could not at that time be so important and necessary, as to
enable us to determine whether they were acquainted with it; whereas,
on the other hand, green vitriol and alum can easily be distinguished
among the materials for dyeing.
Nay, if this salt had been then made, as it is made at present in
Egypt, and if any allusion to it were found, one might readily
conjecture that sal-ammoniac were really meant. But even though it
must be admitted that traces of sublimation being employed occur in
the writings of Dioscorides and others, who lived nearly at the same
period, we are not authorized to suppose that the knowledge of it was
sufficient for the preparation of this salt.
Besides, there are two properties with which the ancients might have
accidentally become acquainted, and which in that case would have
been sufficient to make known or define to us this salt. In the first
place, by an accidental mixture of quicklime, the strong smell or
unsupportable vapour diffused by the volatile alkali separated from the
acid might have been observed. In the second place, it is very possible
that the complete volatilization of this salt on burning coals may have
been remarked; for it had been long known that common salt decrepitates
in the fire. This excited wonder, and in examining other salts people
were accustomed to observe whether they possessed that property also.
Had any one, with this view, thrown a bit of sal-ammoniac on a burning
coal, he must have seen with astonishment that instead of decrepitating
it became entirely volatilized. For this experiment, however, very pure
sal-ammoniac would have been necessary. Had a little common salt been
mixed with it, decrepitation would not have been altogether prevented;
and if the sal-ammoniac had been rendered impure by earthy particles,
as is almost always the case with the volcanic, some earth at least
would have remained behind on the coals.
The name _sal-ammoniacus_ is indeed old; but as those who, in
consequence of the name, considered the _alumen_ of the ancients to be
our alum, and their _nitrum_ to be our saltpetre, were in an error, we
should be equally so were we to consider their sal-ammoniac to be the
same as ours. Our forefathers believed that the ancient writers were
acquainted with all minerals, as well as with all plants; and when
they discovered a new one, they searched in old books till they found
a name which would suit it, or which at any rate had not been given to
another. Our sal-ammoniac, in all probability, acquired in the same
manner its name, which is not often to be found in the writings of the
ancients[972].
When everything they have said of it is collected and impartially
examined, no proofs will be found that under that name they understood
our sal-ammoniac. On the contrary, one will soon be convinced that
_sal-ammoniacus_ was nothing else than impure marine salt. As the
ancients were not acquainted with the art of separating salts, of
refining and crystallising them, they gave to each variety or kind in
the least different, which was distinguished either by the intermixture
of some foreign substance or by an accidental formation, a particular
name; and, considering the wants of that period, this method was not
so bad. For among the impure saline substances, there were always
some which were found to be fitter than others for certain purposes.
On this account they distinguished with so much care _misy_, _sory_,
_chalcitis_ and _melanteria_, instead of which we use a substance
contained in all these minerals, that is to say, green vitriol. Our
apothecary shops however have at present the lixivious salt under the
name of various plants, from which it is extracted, with different
degrees of purity.
When this is known, it will excite no wonder that the _sal-ammoniacus_
of the ancients was nothing else than our common salt. Dioscorides and
Pliny speak of it expressly as a kind of this salt; and Columella[973],
in a prescription for an eye-salve, recommends rock-salt, either
Spanish, Ammoniacal, or Cappadocian. Pliny says[974] that
_sal-ammoniacus_ was found in the dry sandy deserts of Africa, as far
as the oracle of Ammon. It is stated, both by him and Dioscorides[975],
that this salt can be split or broken into smooth pieces; and the
former adds, that the best are white and transparent; that it however
has an unpleasant taste, but can be used in medicine. In like manner
later physicians, when they wish to prescribe common salt, recommend in
particular the ammoniac. Thus Aetius, who lived in the fifth century,
remarks, that when fossil, or as we say at present native salt, is
employed, ammoniac or Cappadocian ought to be chosen.
From what is said by Pliny, it may with certainty be concluded that
this salt was dug up from pits or mines in Africa; for he relates,
that it appeared wonderful that a piece of it, which in the pit was
very light, became, on exposure to the open air, much heavier. Without
repeating the explanation which he gives of this phænomenon, I shall
only remark, that many kinds of rock-salt, taken from the mines of
Wieliczka, experience the same change in the air; so that blocks which
a labourer can easily carry in the mine, can scarcely be lifted by him
after they have been some time exposed to the air. The cause here is
undoubtedly the same as that which makes many kinds of artificial salt
to become moist and to acquire more weight. In this case it is owing to
some impurity, such as muriate of lime, which is called _sal-ammoniacus
fixus_[976], and which attracts from the atmosphere so much moisture,
that it deliquesces in it to the so-called oil of lime.
Synesius, who was born in Egypt in the fifth century, in the
Pentapolitan town Cyrene, and who resided as bishop in Ptolemais,
the capital of the district, says, in a letter wherein he describes
many rarities of his native country, that what was called
_sal-ammoniacus_[977], both according to its appearance and taste, was
a salt of a good quality, fit for use; that it lay under a soft kind of
stone which covered it like a crust, and that it could be easily dug
up when this stone was removed.
Herodotus, Strabo, Arrian, and others, speak of rock-salt which was dug
up in Ammonia, and carried thence as an article of merchandise. The
first mentions a hill of salt; and we are told by the last, that native
salt was brought to Egypt as a present to the king and others, from the
neighbourhood of the oracle of Ammon, by the priests of that place,
in boxes made of palms worked together. Many pieces were three inches
in length; and because this substance was purer than bay salt, and as
clear as crystal, it was particularly employed in sacrifices. This salt
is certainly that which, under the name of _sal-ammoniacus_, was sent
from Egypt to the king of Persia, like the water of the Nile, as is
related by Athenæus from an historian long since lost[978].
It is also certain that the old Arabian physicians, Avicenna and
Serapion, who both lived in the eleventh century, under the name
_sal-ammoniacus_ understood nothing else than rock-salt. The former
says that it ought to split easily, and to be clear and transparent
like crystal; and the latter states that this salt is cut from the
solid rock, and that it is sometimes clear as crystal, sometimes
reddish, sometimes blackish, sometimes of another colour, sometimes
hard, and sometimes friable, or, as the translator expresses it,
pulverulent. All these colours and properties are not uncommon
in rock-salt, and always proceed, no doubt, from an admixture of
ferruginous earth. Serapion says that this salt was obtained from
Corasini. I shall leave it to others to determine where this country
was situated. He often names it, and says that _mala granata_ and
_bezaar_ were obtained from it. But who knows how the name was written
in the original? And the Arabian author perhaps did not mention the
place where the salt was dug up, but that from which, in his time, it
was procured[979].
In regard to the purpose to which the ancients applied their
_sal-ammoniacus_, it appears that it required only common salt and
not sal-ammoniac. It is oftenest mentioned by the physicians, because
it was the purest table salt that could then be procured. On that
account it has been praised by Scribonius Largus, who lived in the
first century, and by Aetius who lived in the fifth, as well as by
Avicenna, Serapion, and others. I have however not yet met with it
in the writings of Hippocrates or Galen. In the works of the Greek
agriculturists it occurs in a recipe for the preparation of a cement
employed to close up wine vessels[980]. According to a recipe of
Apicius, in his book on cookery, _sal-ammoniacus_ was to be roasted.
By these means this rock-salt lost its water of crystallization and
became stronger. On this account, in Transylvania, Siberia, and other
countries, before it is brought to the table it is pounded and roasted.
Of our sal-ammoniac, however, were it roasted, very little would
remain. But whether the _ammonium_ which Palladius recommends for a
cement[981] be that salt, I will not pretend to determine. On the other
hand, I have no hesitation to contradict the old commentator on Ovid,
who, in a passage where the poet recommends _sal-ammoniacus_ in making
a cosmetic water, understands the resin or gum of that name. Ovid
however had no intention that young women should lacker themselves.
For the reasons therefore already mentioned, I am convinced that
the _sal-ammoniacus_ of the ancients was rock-salt, and not our
_sal-ammoniac_. The oldest commentators also on these writers had no
idea of any other than rock-salt; and it was not till a later period,
when our sal-ammoniac was introduced into commerce, and acquired that
name, that the most learned commentators began expressly to remark,
that the new sal-ammoniac, notwithstanding its appellation, was
different from the _sal-ammoniacus_ of the ancients. As this could not
then be obtained, people used the former, which they considered only
as an artificial substitute for the latter, though it was incapable of
supplying its place. But in more modern times, when our sal-ammoniac
became common, and physicians and mineralogists no longer took the
trouble to read the works of the ancients, some of them, if not the
greater part, spoke in such a manner as if our sal-ammoniac had
been the _sal-ammoniacus_ of the ancients; and it was then generally
believed that it had been, at any rate, known and used since the time
of Dioscorides and Pliny.
No one has maintained this with greater confidence and zeal than F. I.
W. Schröder[982], whose judgement however was perverted by alchemistic
conceits. According to his assertion, the Egyptians practised from the
earliest periods the art of making sal-ammoniac, but they kept it a
secret; and he obscurely hints at the purpose for which these great
chemists used so much salt. He refers, on this occasion, to what Pliny
says of _flos salis_[983], in which he thinks he can find the martial
sal-ammoniac[984] flowers of our chemists, or the so-called _flores
salis ammoniaci martiales_. Those who cannot make this discovery he
declares to be ignorant and blind. This decision, however, when the
character of the person who gives it is considered, cannot dissipate a
single doubt. It is certain that what Dioscorides and Pliny call _flos
salis_ has never yet been defined. It was moist, oily, and saline;
and in the vessels, in which it was sent from Egypt, was grey at the
top, saffron-coloured at the bottom, and emitted a bad smell. The most
ingenious conjecture was that of Cordus[985], who thought that it might
be _sperma ceti_; but though I should prefer this opinion to that of
Schröder, I must confess that, on the grounds adduced by Matthioli and
Conrad Gesner, it has too much against it to be admitted as truth.
The first distinct traces of our sal-ammoniac which I have yet met
with are to be found in the works of the Arabians[986]. In a writing
of Geber, there is a prescription how to purify sal-ammoniac by
sublimation, and in another a receipt for making it; so that there
can be no doubt that the author was acquainted with our salt. But
this furnishes very little towards the history of it. The period when
that celebrated chemist lived is uncertain. If, as Leo says[987], he
flourished a hundred years after Mahomet, that is to say in the eighth
century, his works must have been interpolated with many additions,
which criticism has not yet been able to separate. Many of them cannot
be of great antiquity; and the uncertainty is increased by some of
the editions differing from each other in important passages. Whole
sections, which some have, are wanting in others; and the titles and
order of the books and sections are different almost in each. When the
same circumstances are found in several editions, it is observed that
they essentially differ. What, therefore, is now found in the writings
of Geber, as they are called, was certainly not all known in the eighth
century.
The same uncertainty prevails in regard to the chemical works of
Avicenna, who lived in the beginning of the eleventh century, and who
certainly treats of sal-ammoniac. But when these are compared with the
medical works of this author, which are subject to no doubt, it is
evidently perceived that the former must have been the production of a
very different and much younger writer. In the works of the physician
Avicenna, _sal-ammoniacus_ means always rock-salt. It is worthy of
remark, that Avicenna the chemist says, that sal-ammoniac comes from
Egypt, India, and Forperia.
We know with more certainty that Albucasis, or Bulcasis, was acquainted
with sal-ammoniac, as well as the method of preparing it, which he
describes, and also the preparation of medicines in general, in his
book often printed under the title of _Liber servitoris_[988]. However
unintelligible the translation often is, one can easily discover in
what manner sublimation was formerly performed in earthen vessels. But
the period when this Arabian writer lived is doubtful, though it is
generally admitted that he died in the year 1122.
But whence did Europe obtain this salt, in the twelfth and succeeding
centuries? When and in what manner was the preparation of it found
out in Egypt? For what purpose was it first used by our ancestors? I
have not yet met with any information to enable me to answer these
questions, though it is probable that it might be found in old books
of travels, and particularly in the works of Arabian writers. In the
valuable but not altogether intelligible book of Pegolotti[989], from
which I have learned many things respecting the trade of the fourteenth
and fifteenth centuries, nothing is said in regard to the place where
it was obtained, but that it was procured in white, hard, and opake
cakes. It is mentioned in the custom-house tariff of Pisa for the year
1408.
Biringoccio, who lived in the end of the fifteenth and beginning of
the following century[990], knew nothing more than that, according to
report, it came from Cyrene or Armenia. Cæsalpin, his contemporary,
gave, for the preparation of it, a prescription which is undoubtedly
borrowed from the Arabians. This author says, very properly, that it is
obtained in white transparent cakes, blackish on the outside; but adds,
erroneously, that it comes from Germany, though the same thing has been
repeated by Brasavolus and Matthioli. Porta says, with more truth, that
it comes from the East. He asserts also, that he was the first person
who found real sal-ammoniac on volcanic mountains, and he wishes that
his discovery might be confirmed by skilful naturalists[991]. This
may serve as an additional proof, were such necessary, in opposition
to those who think that the first real sal-ammoniac introduced into
commerce was the volcanic. Imperato considers Porta’s observation
as generally acknowledged, but without naming him. The former has
described, in a fuller and more correct manner than any of his
predecessors, the properties of sal-ammoniac[992]; and he states, as
does also Agricola[993], that it is entirely dissipated in the fire. He
adds, that it promotes the production of a celestial blue colour, and
in all probability he here alludes to a solution of copper.
Without attempting to examine at what time the art was discovered
of converting the nitric acid into aqua regia by the addition of
sal-ammoniac, I shall only remark that, at any rate, it was known in
the sixteenth century; for Imperato says that sal-ammoniac is employed
in the solution of gold; and Biringoccio[994], who is older, recommends
nitrous acid prepared with sal-ammoniac for dissolving metals, and
particularly gold. I will not either determine how old the use of this
salt is in soldering and tinning; but I must observe, that it was known
to Agricola[995] and Imperato. I however doubt whether it was very
common, because Biringoccio[996] recommends borax for that purpose,
without so much as mentioning sal-ammoniac; though it is possible that
I may have overlooked it.
We are now arrived at the modern history, which I shall give in as
brief a manner as I can, because it has been already fully treated on
by others. What was long ago shown by the celebrated Mr. Boyle was
proved in the year 1716 by Geoffroy the younger, that sal-ammoniac was
composed of the muriatic acid and volatile alkali, and that it could
be thence prepared in Europe by sublimation[997]. In the same year
the jesuit Sicard gave the first certain account of the sal-ammoniac
manufactories at Damayer, in the Delta, and described in what manner
this salt was prepared there, by sublimation in glass vessels, from
the soot of the burnt dung of camels and cows, which is used in Egypt
for fuel, with the addition of sea salt and urine[998]. In the year
1719, the Academy of Sciences at Paris received from Lemere, the
French consul at Cairo, an account of the process employed; but it
contained no mention either of sea salt or of urine[999]. Afterwards
this information was in part confirmed, and in part rectified and
enlarged, by Paul Lucas[1000], Granger, or, as he was properly called,
Tourtechot[1001], and the celebrated travellers Shaw, Pocock, Norden,
Hasselquist, Niebuhr, and Mariti.
Several writers have asserted that sal-ammoniac comes also from the
East Indies. It is mentioned by Tavernier among the wares which in
his time were brought from Amadabat, in the territories of the Mogul,
to Surat; and Geoffroy states, that when the trade of Marseilles
was interrupted by the plague, the French obtained from Holland
sal-ammoniac, which was shaped like a truncated cone, and was given out
to be Indian[1002]. Pomet also says, that some of the same kind was
formerly procured from Venice and Holland. But Gaubius asserts that he
was never able to hear of any such sal-ammoniac in Holland[1003]; nor
is it to be found in the price currents of the East India Company. I
am almost inclined to suspect that these truncated cones were formed
by the merchants from broken pieces or fragments of the Egyptian
sal-ammoniac, by solution and imperfect crystallization or sublimation.
In this manner the merchants at Marseilles convert the refuse of the
Egyptian sal-ammoniac into cakes by a new sublimation, in order that
it may become more saleable, though it is not readily purchased by
artists. Gaubius, however, has described a kind of sal-ammoniac which
he obtained from India, with the information that it was made in
Hindostan from the soot of animal dung; but in my opinion this requires
further confirmation[1004].
Where and at what time the first works for making sal-ammoniac were
established in Europe, I am not able to determine. The account given
by Thurneisser, that the first sal-ammoniac was made in the Tyrol in
the ninth century, is truly ridiculous. It is not worth the trouble to
inquire where he or Paracelsus found this foolish assertion. One might
be almost induced to believe, that in the time of Boyle there were
manufactories of sal-ammoniac in Europe[1005]. But perhaps there may
be no other foundation for all this than the before-mentioned assertion
of Cæsalpinus, that this salt came from Germany. At Bamberg, the
Germans were long accustomed to boil the sediment of the salt-pans with
old urine, and to sell it cheap for sal-ammoniac; and Weber asserts
that some of the same kind is still made at Vienna. The hundred weight
costs from twenty to thirty florins, but the refuse may be purchased
for a mere trifle. If I am not mistaken, the first real manufactories
of sal-ammoniac were established in Scotland; and the oldest of these,
perhaps, was that erected by Dovin and Hutton at Edinburgh in 1756,
and which, like many in England, manufactures this salt on a large
scale[1006]. Among the later undertakings of this kind is Gravenhorst’s
manufactory at Brunswick, and that which in the neighbourhood of
Gothenburg manufactures sal-ammoniac from the refuse left in making
train oil.
[Sal-ammoniac is now prepared either by the destructive distillation of
bones or coal. The gas-liquor supplies, we believe, the largest part.
This fluid contains hydrosulphuret and carbonate with some other salts
of ammonia. It is decomposed with sulphuric acid, and on evaporation
the sulphate of ammonia is obtained in a crystalline state. This is
then mixed with common salt and the mixture heated in iron vessels,
whereupon the muriate of ammonia sublimes.
Sal-ammoniac is exported in considerable quantities to Russia and other
parts of the continent and to the United States.]