348 X.'s Reply to Mr. Daniell. [Nov. 



trous oxide expended, the sum expressed the whole hydrogen 

 of the alkali. 



In this more summary method of analysis, results were ob- 

 tained, which fully confirmed those established by electrical 

 agency, alt concurring to prove that ammonia affords, by de- 

 composition, a quantity of nitrogen and hydrogen gases equi- 

 valent to twice its volume, and consisting of 1 volume of ni- 

 trogen and 3 of hydrogen. To preserve, however, an agree- 

 ment between the theory of volumes and that of atoms, it is 

 necessary rather to view ammonia as constituted of 2 volumes 

 of nitrogen and 6 of hydrogen. For since 2 volumes of hy- 

 drogen unite with 1 of oxygen to form water, every ultimate 

 volume of hydrogen, (on the supposition that water is consti- 

 tuted of an atom of each of its elements) must, like the ulti- 

 mate volume of nitrogen, be double that of oxygen. Two 

 appreciable volumes of nitrogen, and two of hvdrogen, will 

 contain then the same number of ultimate particles or atoms, 

 and multiples of 2 in volume of either gas, will be multiples of 

 the numbers of single atoms of hydrogen or nitrogen. It must 

 be acknowledged to be remarkable that the only known com- 

 pound of nitrogen and hydrogen should, according to this view, 

 be c6nstituted of one atom of the former element and three of 

 the latter; and that, during the decomposition of ammonia by 

 electricity, those elements, disunited from each other, should 

 not recombine in new proportions, as happens to the elements 

 constituting the aeriform compounds of nitrogen and oxygen, 

 when subjected to the same decomposing influence. 



Article VII. 

 Reply to Mr. Daniell. 

 (To the Editors of the Annals of Philosophy .) 

 GENTLEMEN, OcM5,1824. 



Mr. Daniell having replied to my remarks on a part of 

 his work, I hope you will give a place to what follows : 



In Mr. D's first quotation he might have put the words " other 

 circumstances being alike," in italics, the scope of my paper 

 plainly showing that no effect of heat, except that of dilating 

 the tube and its contents, was to be matter of discussion in as 

 far as he was concerned. This restriction being now accurately 

 understood, I proceed. 



In the matter at issue between us, I must take the liberty of 

 saying, that Mr. D.'s reply is totally incomprehensible and irre- 

 levant. Mr. D. is the first who ever used the fraction of the 

 apparent dilatation of mercury for correcting the observed 

 height of the barometer ; and since all writers, without excep- 



