by Dr Thomas Young 441 



"but as to the marine acid, and acid of tartar, it does not appear that they are 

 capable of losing their acidity by any union with phlogiston" and the acids of 

 sugar and tartar become even less acid by a further dephlogistication. It is 

 obvious that this argument amounts only to an exception, and not to a total 

 denial of the truth of the theory: M. Cuvier has even asserted that the anti- 

 phlogistic theory derived its first origin from one great discovery of Mr Cavendish, 

 that of the nature of hydrogen gas, and owed its complete establishment to 

 another, that of the composition of water: but it would be unjust to deny to 

 Lavoisier the merit of considerable originality in his doctrines respecting the 

 combinations of oxygen ; and however he may have been partly anticipated by 

 Hooke and Mayow, it was certainly from him that the modern English chemists 

 immediately derived the true knowledge of the constitution of the atmosphere, 

 which they did not admit without some hesitation, but which they did ultimately 

 admit when they found the evidence irresistible. On the other hand, it has 

 been sufficiently established, since Mr Cavendish's death, by the enlightened 

 researches of the most original of all chemists, that Lavoisier had carried his 

 generalization too far; and it must ever be remembered, to the honour of 

 Mr Cavendish, and to the credit of this country, that we had not all been seduced, 

 by the dazzling semblance of universal laws, to admit facts as demonstrated 

 which were only made plausible by a slight and imperfect analogy. 



11. Answer to Mr Kirwan's Remarks upon the Experiments on Air. (Phil. 

 Trans. 1784, p. 170.) Mr Kirwan, relying on the results of some inaccurate 

 experiments, had objected to those conclusions which form the principal basis 

 of the antiphlogistic theory. Mr Cavendish repeated such of these experiments 

 as seemed to be the most ambiguous, and repelled the objections; showing, in 

 particular, that when fixed air was derived from the combustion of iron, it was 

 only to be referred to the plumbago, shown by Bergmann to exist in it, which 

 was well known to be capable, in common with other carbonaceous substances, 

 of affording fixed air. 



12. Experiments on Air. (Phil. Trans. 1785, p. 372.) The discovery of the 

 composition of the nitric acid is here further established; and it is shown that 

 the whole, or very nearly * the whole of the irrespirable part of the atmosphere 

 is convertible into this acid, when mixed with oxygen, and subjected to the 

 operation of the electric spark: the fixed air, sometimes obtained during the 

 process, being wholly dependent on the presence of some organic substances. 



13. An Account of Experiments made bv Mr John Macnab, at Henley House, 

 Hudson's Bay, relating to Freezing Mixtures. (Phil. Trans. 1786, p. 241.) From 

 these experiments Mr Cavendish infers the existence of two distinct species of 

 congelation in mixed liquids, which he calls the Aqueous and Spirituous Conge- 

 lations, and of several alternations of easy and difficult congelation when the 

 strength is varied, both in the case of the mineral acids and of spirit of wine. 

 The greatest degree of cold obtained was y8J. 



[* That is, except the argon and other inert gases contained in Cavendish's 

 residue.] 



28-5 



