$68 On the Compojition of AzoU, 



cfcape at the commencement of the down ftroke, it will have another opportunity at 

 the commencement of the up ftroke, for then the bottom valve opens before that in the 

 pifton can fhut, and the air in the barrel will again be at liberty to exert its fuperior 

 ipring to get back into the receiver. 



It is with the grcateft diffidence I put this queftion, having the higheft refpeft for 

 Mr. Cuthberton's abilities. 



If I have advanced what is erroneous, or if I have miftaken the principle of the inftru- 

 znent, I beg to be corredted and informed. 



VI. 



A Memoir, in which the Queflion is examined, whether Azote he a Jimple or compound 



Bidy? By CHRISTOPHER GiRTANSER, Doilor of Phyfic at Gottingtn. 



(Concluded from page i^i') 



X^ ROM this experiment we fee that pure hydrogen gas combines with the oxygen ga» 

 which had remained in the lungs, and forms azote gas. 



1 6. Another experiment, which appears to me to confirm my opinion, was made by 

 Mr. Henry of Manchefter. He repeated it feveral times, and always with the fame 

 fuccefs. His explanation of this phenomenon may be feen in Scherer's Journal, which is 

 different from mine, becaufe he confidercd azote as a fimple body. His experiment is as 

 follows : — In a recurved tube over mercury a mixture was made of 94,5 meafures of car- 

 bonated hydrogen gas from acetitc of pot-a(h, and 107,5 meafures of very pure oxygen gas 

 obtained from the oxygenated muriate of pot-afti. The mixture amounting to 202 

 meafures, was reduced, by an eleflric explofion pafled through it, to 128,5 meafures, and 

 afterwards by lime water to 54,0 meafures. So that in this experiment 23 meafures of 

 azote gas were produced by the electric explofion of the oxygen united with the hydrogen. 



17. Of all known bodies zinc is, if I am not deceived, that which moft eafiiy unites 

 with oxygen ; it takes it from almoft every other body, and this property renders it 

 highly ufeful for the exhibiting the minuteft quantities of oxygen. It was more par- 

 ticularly by means of zinc that I fucceeded in feparating the oxygen of the muriatic acid 

 from its bafe. I have likewife ufed it to make the laft analyfis of ammoniac. Filings of 

 zinc are to be mixed in a retort, with concentrated fluid ammoniac. A communication 

 being- thus made between the retort and the pneumatic apparatus, the whole being kept in 

 digeftion for feveral days, taking care not to raife the heat too much, the ammoniac isde-. 

 Compofed. The oxyde of zinc remains in the retort, and in the pneumatic apparatus a 

 confiderable quantity of hydrogen gas is obtained, together with a fmall quantity of 

 ammoniacal gas and of undecompofed azote.' It is eafy 10 prove that the hydrogen gas was 



not 



