1822.] Sixth Edition of his Syste^n of Chemistry. 267 



will find a set of experiments on it detailed, and my conclusion 

 from them, as follows : " It is a substance of a nature quite 

 peculiar, and seems to consist of the two gases simply combined 

 together." I did not determine the proportions in which the 

 two gases unite ; that was reserved for Cohn and Robiquet 4 

 but my experiments left me in no doubt respecting the consti- 

 tuents. 



" Jn the same paper we find him using for another analysis an 

 defiant gas, which, by his own account, contained 16 per cent, 

 of common air, and the oxygen gas was mixed with 1 1 per cent, 

 of common air. We would hke to know how he ascertained so 

 precisely the proportion of common air when he was in the habit 

 of operating with such impure materials." — (Review, p. 144.) 



I shall gratify this laudable curiosity of the Reviewer. I 

 ascertained the volume of oxygen gas in the defiant gas by 

 means of nitrous gas, employing Dalton's formula for the pur- 

 pose. This volume, when found, 1 multiplied by 5, and consi- 

 dered the product as the volume of common air mixed with the 

 olefiant gas. I ascertained by repeated trials the volume of pure 

 hydrogen, which left the smallest residue when detonated with 

 the oxygen gas. The pure oxygen was obtained by taking half 

 the volume of this hydrogen gas. The residual volume I consi- 

 dered as azote. To it 1 added one-fourth of its volume, and 

 called the sum the vx)lume of common air present. Oxygen 

 containing 1-1 1th of its bulk of common air is far from impure. 

 It contains about 92 per cent, of pure oxygen, and only 8 per 

 cent, of azote. With such a gas, very good results may be 

 obtained. Indeed in many cases it is expedient to diminish the 

 purity of the oxygen gas employed, by mixing it with a certain 

 portion of common air. 



12. But we come now to what the Reviewer seems to have 

 considered as his master-piece, — his defence of Mr. Brande's 

 notion, that carburetted hydrogen gas is merely a mixture of 

 olefiant gas and hydrogen gas. By this time I dare say he is 

 ashamed of w^hat he has written on this subject, and would 

 willingly barter nine-tenths of his wit for one-tenth of my preci- 

 sion. For Dr. Henry's paper published last summer in the Phi- 

 losophical Transactions has demonstrated the peculiar nature of 

 this gas, if any demonstration was necessary. Indeed my state- 

 ment in the Aimak of Philosophy^ xvi. 380, was decisive of the 

 inaccuracy of Brande's views. That a mechanical mixture of 

 three volumes of olefiant gas and two volumes of hydrogen 

 should be uniformly extricated from stagnant water in all places 

 would be truly miraculous. Dr. Henry found its specific gravity 

 the same as I had done, and that specific gravity is incompatible 

 with Brande's notion, as are indeed all the properties of the gas. 

 The Reviewer has mis-stated my reasoning in the Annals ; but 

 it is not worth while to put him right. If Mr. Brande chooses 

 to persist in his opinion in the face of common sense, I have 



