5oS 



ON CARBURETED 



I find, that the specific gravity of the pure gas 

 would have been 0.5554*. 



My method of taking the specific gravity of 



gases being extremely simple, yet precise, I think 

 it worth while to describe it in this place. It is 

 founded on the well-known fact, that when two 

 gases are mixed, their bulk does not alter. I have 

 a large flask fitted with a stop-cock. I weigh this 

 flask very accurately, then exhaust it, and weigh 

 it again. Let the loss of weight be a. I then fill 

 the flask with the gas whose specific gravity I 

 want, and weigh it again. If the weight of the 

 flask be the same as at first, it is obvious that the 

 gas has exactly the specific gravity of common air. 

 If it be heavier than at first, the gas is heavier 

 than common air ; if lighter, the gas is lighter than 

 common air. Suppose the flask lighter than at 

 first, I add weights till the flask is exactly poised. 

 Let the weight added be b. We have the weight 

 of common air to that of the gas as a to a — b. And 

 to find the specific gravity, we have this propor- 

 tion, a : a — b ; : 1 : x ~ specific gravity wanted, 



a 



b 



If the flask is heavier than at first, 



or x 



a 



* Let x = the specific gravity of the pure gas, A — 

 the quantity of air in the mixture, a— the specific 

 gravity of air, B— quantity of pure gas present, c— speci- 



fic gravity of the mixture, we have x — 



