440 Life of Cavendish 



the common doctrine of caloric, unless we admit that caloric could have existed 

 in the neighbouring bodies in the form of cold, or of something else that could 

 be converted into caloric by the operation ; and this transmutation would still 

 be nearly synonymous with generation, in the sense here intended. However 

 this may be, it is certain that, notwithstanding all the experiments of Count 

 Rumford, Dr Haldalt, and others, Sir Humphry has been less successful in 

 persuading his contemporaries of the truth of Mr Cavendish's doctrine of heat, 

 than in establishing the probability of his opinions respecting the muriatic acid. 



10. Experiments on Air. (Phil. Trans. 1784, p. 119.) This paper contains 

 an account of two of the greatest discoveries in chemistry that have ever yet 

 been made public the composition of water, and that of the nitric acid. The 

 author first establishes the radical difference of hydrogen from nitrogen or 

 azote ; he then proceeds to relate his experiments on the combustion of hydrogen 

 with oxygen, which had partly been suggested by a cursory observation of 

 Mr Warltire, a Lecturer on Natural Philosophy, and which prove that pure 

 water is the result of the process, provided that no nitrogen be present *. These 

 experiments were first made in 1781, and were then mentioned to Dr Priestley; 

 and when they were first communicated to Lavoisier, he found some difficulty 

 in believing them to be accurate. The second series of experiments demonstrates 

 that when phlogisticated air, or nitrogen, is present in the process, some nitric 

 acid is produced; and that this acid may be obtained from atmospheric air by 

 the repeated operation of the electrical spark. 



It has been supposed by one of Mr Cavendish's biographers, that if 

 Mr Kirwan, instead of opposing, had adopted his chemical opinions, "he would 

 never have been obliged to yield to his French antagonists, and the anti- 

 phlogistic theory would never have gained ground." But in this supposition 

 there seems to be a little of national prejudice. Mr Cavendish by no means 

 dissented from the whole of the antiphlogistic theory ; and in this paper he has 

 quoted Lavoisier and Scheele in terms of approbation, as having suggested the 

 opinion "that dephlogisticated and phlogisticated air are quite distinct sub- 

 stances, and not differing only in their degree of phlogistication, and that 

 common air is a mixture of the two." He afterwards mentions several memoirs 

 of Lavoisier in which phlogiston is entirely discarded; and says that "not only 

 the foregoing experiments, but most other phenomena of nature, seem explicable 

 as well, or nearly as well, upon this as upon the commonly believed principle 

 of phlogiston"; and after stating a slight conjectural objection, derived from 

 the chemical constitution of vegetables, he proceeds finally to observe, that 

 "Lavoisier endeavours to prove that dephlogisticated air is the acidifying 

 principle": this is no more than saying, that acids lose their acidity by uniting 

 to phlogiston, which, with regard to the nitrous, vitriolic, phosphoric, and 

 arsenical acids, is certainly true, and probably with regard to the acid of sugar; 



* M. Arago, in his liloge of Watt, attempted to transfer to that philosopher the 

 merit of this great discovery, and thus gave rise to a vehement controversy, which 

 has been finally and conclusively settled in favour of Cavendish by Dr Wilson, of- 

 Edinburgh. See his Life of Cavendish, 1 85 1 . Note by the Editor [Dean Peacock, 1 855 .] 



