iyo On the Compofuion of Azote and 



Cultivated earth, brought into contaft with the atmofphere, abforbs the oxygen, and 

 forms azote. In countries Ctuated near the poles, and on the top of the Alps, where the 

 earth is always covered with fnow, the atmofpheiic air contains a greater quantity of 

 oxygen than in fouthern or low countries, becaufe the fnow prevents the air from coming 

 into contaft with the earth. 



The conftituent principles of azote being now known, we are enabled to form a new theory 

 of the art of making nitre. In the Annals of Chcmiftry, Vol. XX. I obferve fome valuable ob- 

 fervations on this fubjeft. For inftance, p. 313, " Earth extrafted from deep fubterraneous 

 " places, inacceflible to the light, fuch as caverns, requires only to be expofed to the air 

 " a few days to produce falt-petre in abundance. It is proper to obferve, that thefc earths 

 *' do not furni(h a fingle atom of nitre when they are firft taken from the moift and dark 

 " place where they were formed ; and that it is only by combination or combuftion of the 

 *' azote of the earth with the oxygen of the atmofphere that this fait is produced." 



The explanation which is given, page 3 [4, of that interefting phenomenon, is a proof 

 how diftant we were from the truth before the nature of azote was undeiftood. 



As lime abforbes oxygen with avidity, we fee the caufe why rooms that have been 

 newly white-waflied are unwhblefome. 



The following bodies are combinations of hydrogen with oxygen in different pro- 

 portions: 



Azote. Oxygenated muriatic acid. 



Gafeous oxyde of azote. Nitro- muriatic acid. 



Nitrous gas. Water. 



Nitrous acid. Atmofpheric air. 



Nitric acid. Ammoniac. 



Muriatic acid. 

 1 hope foon to prove that pot-a(h, foda, and fulphur, ought to be added to that lift. 

 Phofphorus appears to me to be hydrogen, in the pureft ftate in which we are acquainted 

 with it } but this I am very far from having it in my power to prove. The analyfis of fixed 

 alkalis is completed. As, however, I have no intention of faying any thing upon that 

 fubjeft in the prefent article, I (hall confine myfelf to pointing out one of the decifive ex- 

 periments. When an alkali is fufed with filiceous earth to make glafs, the alkali is 

 analyfed. The hydrogen efcapes under the form of gas, and the oxygen becomes com- 

 bined with the filiceous earth ; glafs being merely an oxyde of filex. Too great a quantity 

 of oxygen (hould not be admitted, as it renders it lefs tranfparent ; for this reafon it is 

 ufual to add fiibftances which ftrongly attract oxygen, fuch as manganefe. 



Mr. Mayer, to whom I had communicated the refult of my experiments, by which I fo 

 evidently confirmed an idea which he had ventured to throw out, and of which he has the 

 merit of being the author, fent me a paper, from which I (hall give an extraft ; 



»' I am inclined," fays he, " to think with Mr. Dc Luc, that the evaporation of water, 

 ** as it continually takes place on a large fcale in nature, is a real convcrfion of the water 



*' into 



