On the conjiitueni Par-ts of Azot. 34^ 



that they abforb oxygen in lefs time, and in greater quantity, 

 when they are heatpd. I found, by other experiments, thai 

 earths take the fame oxygen from the water; but that, for 

 this purpofe, a temperature higher than that of the atmo- 

 fphere is required. Argil, argillaceous earth, or alumine, is 

 |hat which takes up oxygen with the greateft aviditVs and at 

 a temperature far below that of boiling w^ter; lime requires 

 a higher temperature, and does not charge itfelf fo much 

 with oxygen ; filex, before it ablbrbs oxygen, muft be brought 

 to a ftate of ignition in the fire, but afterwards it takes it uj) 

 very rapidly. Baked argil yinites itfelf alfo with oxygen, 

 but it requires a higher temperature. Glazed argil does not 

 ^bforb oxvgcn, the glazing being made of metallic glafs, 

 which has jio action on oxygen. 



Having made thefe obfervations, I did not find it difficult 

 to explain the phenomena of the couverfion of water into 

 azotic gas. RecolleiSling the hypothefis which M. Ma\er 

 hiid ventured to ftavt, a. few years ago, on the nature of azoti<!; 

 gas, by fuppqfing that it was a compound of oxygen and 

 hydrogen, water converted into a gas*, I conceived a fimilat 

 idea refpefting it. i\s M, Mayer gave his hypothefis merely 

 as an idea thrown out at hazard, and as he fupported it with 

 no chemical experiment whatever, I propoied to fupply what 

 he had left undone. Admitting this hypothefis, and refleft- 

 ing on the fingular property which earths have of al)forbing 

 the oxygen of water, I explained, without diflicult^', the ex- 

 periments above mentioned. They are the refult of a double, 

 affinity. The oxygen of the water unites itfelf in part to the 

 earth, which is converted into an earthy oxyd ; the remainder 

 of the oxygen in union with the hydrogen combines with 

 . the caloric, and forms azotic gas; confequentlv, azot is water 

 ili-priijcd of a part of its o.vygen. 



This aiTertion is fuppported by various experiments : biil 

 I fliall confine mvfclf to a few only, and (hall rcferve the reft 

 to be mentioned in a fecond memoir, after I have repeated 

 them. 



I. Provide porcelain tubes, and try them by tranfmitting 

 ^hrough them the fteam of boiling water, which will pafs in 



* Grtn'i J'junial der PbyJiJiy Vol. V. p. 381. 



YttpoUf 



