_Of the discoveries in factitious Airs before the time of Dr.
Priestley, and of those made by himself._
Dr. Priestley has given a general though brief account[33] of what
had been done by his predecessors in this department of experimental
Philosophy, and Sir John Pringle in his discourse before the Royal
Society on occasion of presenting Dr. Priestley with the Copley Medal
in 1772[34] has entered expressly, and more fully into the history of
pneumatic discoveries. The same subject was taken up about three years
after by Mr. Lavoisier still more at large, in the introduction to his
first Vol. of Physical and Chemical Essays, of which a translation was
published by Mr. Henry of Manchester in 1776. It is unnecessary to
detail here what they have written on the history of these discoveries.
It may be observed that no mention is made by any of these gentlemen
of an experiment of Mr. John Maud, in July 1736[35], who procured (and
confined) inflammable air from a solution of Iron in the vitriolic
acid. Inflammable air had been procured from the White Haven coal
mines, and exhibited to the Royal Society by Mr. James Lowther, but
I do not recollect any notice of its having been collected from a
solution of metals in acids, and its character ascertained before Mr.
Maud’s experiment; for Hales, though he procured both inflammable and
nitrous air, did not examine their properties. But it is much more
extraordinary that neither Sir John Pringle who was a Physician, or
Mr. Lavoisier who was so much occupied under government, respecting
the Theory of the formation, and the practice of manufacturing
Saltpetre from Nitre beds, should not have known, or have noticed the
five treatises of Mayow on chemical, phisiological and pathological
subjects, published a century preceding. Mayow is quoted by Hales,[36]
by Lemery,[37] and by Brownrigg,[38] but though they appear to have
read his work, it is evident that they knew not how to appreciate, or
to profit by it. Haller[39] also refers to him, and he is respectfully
quoted by Blumenbach[40]: but his book nevertheless long remained
in comparative obscurity. From their time Mayow has been neglected
until his writings were noticed by Dr. Forster, in 1780,[41] and again
announced as almost a discovery in the chemical world, by Dr. Beddoes
in the year 1790. His doctrines touch so nearly on the subsequent
discoveries of Priestley, Scheele, Lavoisier, Crawford, Goodwin, &c.
that it seems absolutely necessary to discuss his pretensions, before
those of his successors can be accurately admitted. As I am acquainted
with Dr. Beddoes’s pamphlet on Mayow, from the analytical review of it
only, (V. vi.) and have no opportunity here of consulting it, I shall
take up Mayow’s book, and give an account of his tenets, from the work
itself.
[33] In the beginning of his first vol. of experiments: it is an
abridgment of Sir J. Pringle’s discourse.
[34] Discourses p. 4.
[35] Martyn’s abridgment of the Philosophical transactions v. 9. p. 396.
I think Maud’s experiment in 1736 likely to have suggested those of Mr.
Cavendish in 1766.
[36] Vegetable Statics v. 2. p. 234.
[37] Mem. de l’Acad. Royale 1717 p. 48. On ne dit pourtant point
trop sous quelle forme ce nitre se contient dans l’air, et Mayou,
Auteur Anglois et grand defenseur du Nitre-Aèrien voulant èclaircir
cette difficultè, suppose l’air impregnè par tout d’une espece de
nitre metaphysique, qui ne merite pas trop d’ètre refutè, quoi-qu’il
l’àit cependant ètè suffisamment par Barchusen et par Schelhamer. Le
fondement de l’opinion du Nitre aèrien, c’est comme le rapporte Mayou
lui mème, qu’apres avoir enlevè à une terre tout le Nitre qu’elle
contenoit, si on l’expose ensuite à l’air pendant un certain tems
elle en reprend de nouveau: il est vrai que si l’observation ètoit
parfaitement telle qu’elle vient d’ètre rapportèe, on auroit une plus
grande raison qu’on n’en a, de supposer dans l’air une très-grande
quantite de nitre, et de mettre sur le compte de ce nitre aèrien un
grand nombre d’effets auquels il n’a certainement aucune part.
The experiment of Lemery mentioned in Dr. Watson’s Essay on Nitre, is
in p. 54 of the Mem. de l’acad. royale for 1717 not for 1731.
It sometimes happens to men whose genius far transcends the level of
their day, to be from that very circumstance neither understood nor
believed by their contemporaries. Until the discoveries of modern
chemistry, who would have given Sir Isaac Newton credit for his
conjecture that the Diamond was an inflammable substance? The fact
which Lemery sneers at, the reproduction of nitre in the earth, is
established beyond contradiction by the authors quoted by Dr. Watson
(Chem. Ess. v. 1. p. 318-321) and in Bowle’s account of the nitre
earths in Spain, and in Andreossi’s memoir on the Saltpetre of Egypt.
Though it is far from improbable that after lixiviation these earths
may again become gradually impregnated with putrefying animal or
vegetable matter to serve for the future crops of nitre.
[38] Philosophical transactions v. 55 p. 232.
[39] Dr. Priestley in his preliminary account of the discoveries and
theories on respiration (Exp. on air v. 3 p. 356. abridged edit.)
quotes Haller’s great work on Physiology. Haller quotes Mayow in three
or four places; but it is no wonder the quotations did not strike
Dr. Priestley with any curiosity to examine Mayow’s book, for Haller
certainly did not understand his theory. For instance Lib. 8. § 13.
Nitrum aereum. Si ad verum sensum nitri aerei hypothesis revocata
fuisset parum utique ab eà differt quam novissimè proposuimus.
Nitrum quidem ipsum incautiosius olim Physiologi in aere obvolitare
scripserunt, et ex pluvià et nive colligi; idemque passim ex rupibus
efflorescere (Sprat ex Henshaw p. 264 major cal. hum.) exque plantis et
stercoribus educi (Fludd Niewentydt, 563-4. Mayow de nitro aereo. Lower
de Corde c. 3. Thurston 52. 53. Besse Analyse tom 1 et en lettre en
reponse à M. Helvet. 114.) id nitrum aiunt in pulmonibus ad sanguinem
venire, et ab eo ruborem illum elegantem, et fermentationem (Mayow,
Thurston penult. ess. T. 3 p. 265) et calorem sanguinis accedere aut
vicissim sanguinem condensari.
Certainly the id nitrum, is not Mayow’s. M. Rosel seems first to have
ascertained the existence of nitre in plants. A late experiment of Dr.
Priestley’s, of which he gave an account in a letter to Dr. Wistar,
seems to make it probable that there may be nitre in snow.
[40] Blumenbach’s Physiology, Caldwell’s translation, Philadelphia,
1795. § 162. Speaking of the theories of animal heat, “But all these
hypotheses are embarrassed with innumerable difficulties; whereas on
the other hand the utmost simplicity, and an entire correspondence with
the phenomena of nature combine in recommending and confirming that
doctrine in which the lungs are considered as the focus or fire place
where animal heat is generated, and the deplogisticated part of the air
which we breathe as the fuel that supports the vital flame. That justly
celebrated character Jo. Mayow sketched out formerly the leading traces
and the first great outlines of this doctrine which in our times has
been greatly improved, extended and farther elucidated by the labours
of the illustrious Crawford.”
Dr. Darwin however is certainly right in supposing that heat is evolved
in many other processes of the animal economy, beside inspiration.
[41] See the translation of Scheele by Dr. John Reinhold Forster 1780 p.
XIII.
In p. 437 of v. 5 of the analytical review of Hopson’s Chemistry,
before Dr. Beddoes’s account of Mayow in 1790 the latter is stated as
the author of discoveries that might have given rise to the present
system of pneumatic Chemistry.
Two of Mayow’s Essays, viz. de Respiratione and de Rachitide, appear
to have been published at Leyden, in 1671, the author who died at the
age of 34, being then 26 years old. The propositions which I have
thought it necessary to extract from Mayow’s work, (ed. of 1674,
Oxford,) and which I shall insert, will give a concise, but faithful
view of his discoveries and conjectures in pneumatic Chemistry.[42]
The abridgements of Beddoes and Fourcroy, I have no opportunity to
consult, and as Mayow’s book is far from being common, I have deemed
it by no means an unnecessary labour to give the reader an opportunity
of judging for himself, what is the precise extent of the claim, which
the patrons of Mayow’s reputation may fairly set up. It is also, of the
more importance in a history of this subject, to notice the pretensions
of this writer, as it appears that Boyle’s experiments on artificial
air, in his physico-mechanical experiments were not made until the
year 1767 et seq. Though the first edition of that treatise repeatedly
quoted by Mayow was in 1661. Mayow’s experiments therefore ought to
have been, and probably were known to Boyle at the publication of his
last edition.[43]
[42] I believe Dr. Beddoes gives no more than the heads of each chapter
and, a brief analysis of the contents. Dr. Beddoes in his remarks on
Fourcroy’s account of Mayow, Ann. de Chimie. No. 85, Nich. Jour. v. 3
quarto p. 108 states Mayow at the time of his death to have been only
27 and 28: but he was born in 1645 and died in 1769. Biog. Dict. 8vo.
ed. of 1798.
[43] I do not find that Boyle quotes Mayow, though their labours in the
same field were contemporary. But Boyle in his hidden qualities of the
air published in 1674 has an observation that looks as if derived from
Mayow. “And this undestroyed springiness of the air, with the necessity
of fresh air to the life of hot animals, suggests a great suspicion of
some vital substance if I may so call it, diffused through the air,
whether it be a volatile nitre or rather some anonymous substance,
sidereal or subterraneal, though not improperly of kin to that which
seems so necessary to the maintenance of other flames.”
The following is an analysis of Mayow’s essays, so far as relates to
his chemical Philosophy.
CHAP. _1st. Of Nitre._ The air is impregnated with a vital, igneous,
and highly fermentative spirit of a nitro-saline nature, p. 1.
Nitre is a salt consisting of an acid and an alkaline part, as appears
by the Analysis, and by the generation of nitre; for if this salt be
deflagrated with sulphur, the acid spirit will fly off, and may be
collected by means of a tubulated retort and a receiver: and so if it
be deflagrated with tartar, the residuum will be equal in weight to the
tartar employed, though much of that, is of a fœtid oily nature. This
appears also from the composition of nitre, by the addition of spirit
of nitre to an alcali, p. 2-4. The fixed part of nitre is obtained from
the earth; pure earth being probably a compound of salt and sulphur.
p. 8.