176 Dr Fyfe on the Use of Steam, 



then the carbonic acid ought to have amounted to 50 per cent. ; 

 that is, the acid and hydi-o-carbon ought to have been in 

 equal volumes ; because water consists of 1 of oxygen, and 2 

 of hydrogen, and 1 of oxygen yields 1 of carbonic acid, and 

 2 of hydrogen also 1 of hydro-carbon. Again, supposing 

 the hydrogen uncombined, the carbonic acid ought to have 

 amounted to 33.3 per cent., or one half of the volume of the hy- 

 drogen, but it was only 18 per cent. Now, if we deduct the 

 oxygen in this from the total amount of oxygen in the steam, 

 there remains 15.3, which, if wc suppose it in the state of car- 

 bonic oxide, would yield 30.6 of that gas ; so that the oxide and 

 hydrogen should in the residual gas, after the abstraction of the 

 carbonic acid, be in the ratio of 30.6: 66.6, that is as 1 to 2.17, 

 or say in round numbers as 1 to 2. 



That this is the composition of the gas, is confirmed by ex- 

 plosion with oxygen in the Volta eudiometer. Though the re- 

 sults varied in different trials, it yielded generally about one- 

 third of its volume of carbonic acid. Now, carbonic oxide when 

 fired with oxygen yields its own volume of acid ; so that suppo- 

 sing the gaseous fluid to contain one-third of its bulk of oxide, it 

 ought to yield the same quantity of acid, which it generally did. 

 Of course, in giving this as its composition, I do not mean to 

 say that it invariably contains exactly these proportions. The 

 difference in specific gravity, and the different results obtained 

 by the action of chlorine, and by the Volta eudiometer, shew 

 that the proportions vary, probably owing to the temperature, 

 or the rapidity with which the steam is passed over the incan- 

 descent charcoal. 



I may here mention that I have endeavoured to detect oxygen 

 in the gas, by exposing it, after being freed of hygrometric mois- 

 ture, to the action of potassium, which decomposes carbonic oxide; 

 depriving it of its oxygen, and causing a deposit of carbon. 

 Though potassium was kept in it for some days, it was not in 

 the least affected ; nor was there any diminution of the gas. I 

 found, however, that when potassium was exposed to carbonic 

 oxide, mixed with about twice its bulk of hydrogen, and both 

 previously dried, it did not suffer any change, though they were 

 kept for some days together, so that we are not, from the want 

 of action with potassium, to infer that the gas evolved by steam, 

 acting on charcoal, does not contain oxvffen. 



