96 Mr Graham on Phosphuretted Hydrogen. 



caustic potash, always loses its spontaneous accendibility, although 

 by no means rapidly, several hours being generally required. 



5. Certain acids appear to have a remarkable power in with- 

 drawing the principle of inflammability from phosphuretted hy- 

 drogen. 



Let phosphuretted hydrogen be transferred into a jar inverted 

 over mercury, of which jar the inner surface has been moistened 

 with concentrated phosphorous acid. A small quantity of a milk- 

 white matter immediately appears in the acid, where exposed to 

 the gas ; and in two or three minutes the gas has ceased to be 

 spontaneously inflammable, without any appreciable diminution 

 of its volume having occurred. This white matter, although 

 very sensible to the eye, exists only in the most minute quantity. 

 It is not crystalline, and perhaps is not even solid. The intro- 

 duction of concentrated phosphoric acid into the gas, was attend- 

 ed by similar phenomena ; and the gas lost its spontaneous in- 

 flammability in the course of hah" an hour. 



A strong solution of arsenic acid acts as rapidly in withdraw- 

 ing the peculiar principle as phosphoric acid does, but the ar- 

 senic acid soon begins to react upon the phosphuretted hydrogen 

 itself, a dark copper-coloured incrustation soon forming upon the 

 surface of the gas-receiver, which matter is probably a phosphuret 

 of arsenic. Concentrated sulphuric acid is capable of absorbing 

 phosphuretted hydrogen itself, which the preceding acids are not, 

 but even sulphuric acid appears to absorb the peculiar principle, 

 in the first instance, by a more active affinity than it exerts up- 

 on the gas itself Dilute phosphorous, phosphoric, and arsenic 

 acids, react in the same manner upon phosphuretted hydrogen, 

 but not so rapidly as the concentrated acids do. 



6. The following liquids are capable of dissolving the quantity 

 of phosphuretted hydrogen gas placed against their names, at 

 65° Fahr, 



