204 AC1DIF1ABLE COMBUSTILBES. 



and plunging its beak into a trough containing re- 

 cently boiled water, or water in which some deut- 

 oxide of azote has been agitated ; the gas is extri- 

 cated with considerable rapidity ; it is colourless, 

 has a smell somewhat similar to that of garlic, and 

 takes fire spontaneously when it comes in con- 

 tact with common air. Water absorbs about 5 

 per cent, of its volume of it. The specific gra- 

 vity of this gas from a mean of some very care- 

 ful experiments made in my laboratory, is 

 0-902735. But I have elsewhere shown that its 

 true specific gravity is 0'90277 5* which exceeds 

 the experimental result by an almost inapprecia- 

 ble quantity. 



When phosphorus is heated in hydrogen gas, 

 a portion of phosphuretted hydrogen gas is 

 formed ; but the_ volume of the original gas is 

 not increased. It is obvious from this, that a 

 volume of phosphuretted hydrogen gas contains 

 just a volume of hydrogen gas. Hence, if from 

 the specific gravity of phosphuretted hydrogen 

 gas we subtract the specific gravity of hydrogen 

 gas, the remainder will represent the weight of 

 phosphorus united to a volume of hydrogen gas. 



Sp. gr. of phosphuretted hydrogen gas 0*90277 

 hydrogen gas 0-06944. 



Phosphorus = 0-83333 



* Annals of Philosophy, XVI, 262. 



