On thi Cotnpqfition of Azote. 169 



Clay, loamy earth, or alumine, become charged with oxigen with the moft avidity, and at 

 a temperature far below that of boiling water. Lime requires a more elevated temperature, 

 and does not abfoib fo much oxigen. Silex requires to be ignited before it will abforb 

 oxigen, but then it feizes it rapidly enough. Baked clay alfo unites with oxigen, but re- 

 quires a ftill more elevated temperature. Glazed clay does not abforb oxygen, becaufe the 

 glaze being a metallic glafs, has no adtion upon that fubftance. 



Having made thefe obfervations, I did not find much difficulty in explaining the pheno- 

 mena of the change of water into azote gas; RecollecSling the hypothefis which was 

 thrown out by Mr. Mayer fome years ago, on the nature of azote gas, which he fuppofes 

 to be compofed of oxigen and hydrogen, or.thatitis water changed into gas*, I adopted 

 fimilar ideas refpe£ling the nature of this gas. Mr. Mayer having given his hypothefis 

 merely as a conjedlure, unfupported by any chemical experiment whatever, I propofed to 

 fupply what was wanting in the eftablifhment of hisconclufion. 



Admitting this hypothefis, and reflefting on the fingular property wliich the earths 

 pofiefs of abforbing oxigen from water, I explained the before related experiments without 

 difficulty. They are the confequence of a double affinity. The oxigen of the water partly 

 unites with the earth, and converts it into an earthy oxide ; the reft of the oxigen uniting 

 with the hydrogen combines with the caloric, and forms azote gas ; whence it follows, 

 that azote is luater deprived of part of its oxigen. 



Several experiments prefent themfelves in fupport of this aflertion. I fhall confine my- 

 felf to mentioning fome of them, and (hall fpeak of the others in a fecond memoir, when 

 I {hall have repeated them. 



1. Let tubes of porcelain be procured and tried, by paffing the vapour of boiling water 

 through them, which will be condenfed at the other extremity without the fmalleft particle 

 of gas, excepting the air which is contained in the retort. After having in this manner 

 afcertained that the water is not changed into gas in thefe tubes, in order to obviate the 

 objedions of thofe who imagine, that the external air pafl"e3 through thefe tubes ; let one 

 of them be filled with tin filings and placed in a fire, taking care to keep it up : after 

 which the vapours of water are to be pafled through. 



The pneumatic apparatus will be found to contain azote gas mixed with oxigen gas. 

 The tin is changed into oxide, which oxide pafles under the pneumatic apparatus with the 

 azote gas, and the vapours of the water. 



This experiment, which was made by Mr. Van Hauch, is eafily explained according to 

 my theory. The tin takes only part of the oxigen from the water. The reft unites with 

 hydrogen and forms azote. 



2. When the vapours of water are pafled over lead in the fame manner as in the fore- 

 going experiment, a fimilar refult is obtained according to Mr. Van Hauch. At the 

 commencement of the operation, the oxide of lead pafles into the inverted receiver along 



• Gren't Journal derPhyfik, vol. v. page jSi, 

 Vol. IV. — ^JuLY 1800. Z with 



