Pretended Compojidon of Azote, 379 



If water be paffed through a tube of porcelain containing lead, this metal is converted 

 partly to the ftate of yellow oxide, and becomes Titrified ; but there is no difengagement 

 of azote gas. 



If, inftead of lead, tin is put into the tube, that metal becomes oxidated, and hydrogen 

 gas is obtained. Zinc aiFords the fame refult. 



To afcettain whether this hydrogen gas did not contain azote gas. Citizen Bouillon la 

 Grange caufed it to pafs over fulphur in fufion, and he obtained fuiphurated hydrogen 

 gas, but no azote. He afterwards fubjefted it to another trial. 



He mixed the hydrogen gas which he had obtained by means of zinc, with oxygen 

 gas ; he fet the mixture on fire by an eletlric fpark j water was formed, but there was na 

 azote gas. 



The opinion of Girtanner agrees with that of Humboldt, refpefling the abforption of 

 oxigen by fimple earths, and particularly by alum ; there is, neverthelefs, this difference, 

 that Humboldt confiders the fuppofed phenomenon as a fimple feparation of the oxygen 

 which becomes fixed from the azote which remains in the gafeous flate; but according to 

 Girtanner, " the azote which is obtained in our experiments being always produced by 

 " operation itfelf, and having no exiftence in the form of azote before the experiment in 

 ** the air which is examined. Von Humboldt, who is fond of drawing general conclufions 

 " from folitary fadls appears to be deceived, when he afferts that earths may be ufed for 

 " the purpofe of determining the quantity of azote contained in the atmofpheric air : for the 

 " earths do not indicate that azote is contained in atmofperic air 5 they change this air into 

 ** azote." 



The younger Sauffure has formerly contradifted the refult announced by KumboMt, 

 ( Journ. de Phyf. frim. an. 7.) He allows that the humus, which is the refult of the mixture 

 of decompofed vegetables with other vegetables which are not yet decompofed, abforbs the 

 oxigen gas, and that this is a known faft •■, but he attefts, " that this effe£l never takes 

 " place when the earths are pure and deprived of every vegetable fubftance." He de- 

 fcribes feveral experiments which he made with alumine, lime, and filex. 



In the journal of Pluviofe, of the fame year, tliere is a reply from Humboldt, written in a 

 magifterial tone. It contains nearly the fame affertions as are contained in the firft Me- 

 moir with the addition, however, (as a kind of fanflion), that his obfervations were made 

 in the laboratories of Vauquelin and of Fourcroy. This authority would undoubtedly be 

 of great weight, if thefe two learned chemifts had co-operated in the obfervations ; but very 

 far from that being the cafe it is vifible from the account that the only experiments,, which 

 were attempted in their prefence, did not fuccecd. 



I have been affured that the celebrated Fabroni, about the fame period, repeated the ex- 

 periments of Humboldt, at Florence, without any fuccefs. 



Champy, the fon, a very accurate obferver, repeated them at Cairo upon alumine, upon 

 lime, and upon the mud of the Nile,, with a temperature which varied from 30 to 36° de- 

 grees of the centigrade thermometer, but he obtained no abforption. It muft be remarked,, 



that. 



