45^^ tJITROUS AClfJ. 



fphere? as a ftandard, the oxygenous and the carbonic 3ci^ 

 will obferve a decreafing ratio to it in afcending, and the 

 aqueous vapour an increafing one. The fpecific gravity of 

 oxygenous and azotic gases being as feven to fix nearly, their 

 diminution in denfity will be the fame at heights reciprocally 

 as their fpecific gravities. Hence it would be found, that at 

 the height of Mount Blanc (nearly three Englifti miles) the 

 j'atio of oxygenous gas to azotic in a given volume of air^, 

 would be nearly as 20 to SO ;— confequently it fpllows that at 

 any ordinary heights the difference in the proportions will be 

 fcarcely if it all perceptible ^, 



Obfervation which indicates a fpontaneous Decompofition of 

 nitrous Acid and Formation of Amnionia. B\f D. A. 



To Mr. NICHOLSON. 

 SIR, " 



Decomposition 1 SE>J'D you a flatement of (he following fa£t, in c^fe it 

 of nitrous acid, ^^^ j^qj hithcflo have been obferved ; it feenns to fhew the 

 mutual decompofition of nitrous acid and aimoCpheric air ; 

 but the explanation of the theory I will l^ave to you, or fome 

 qS your learned correfpondenfs. A phial of bright orange 

 coloured nitrous acid, fo looliely flopped that bubbles of gas 

 efcaped every five or ten minutes, having ftood \!vjlbin a fevy 

 inches of a bpltle of muriatic acid, clofely flopped foj; above 

 a twelvemopth, my attention was attraQed by pbferving g 

 white incruftation of falls upon the label paper of the laft 

 mentioned phial. To determine their nature, dilTolved them 

 in diflijled water; dropped a little nitric acid in, to faturate 

 any uncombined alcalies ; then with nitjrate of filver, ^co- 

 pious precipitate was formed, whjch indicates the muriatic to 

 be the acid ; when I faturated the acids with pure potafs, the 



• Air brought from the fummit of Helvelyn, in Cumberland 

 (1100' yards above t^e fea — Barometer being 26,60) in July 1804, 

 ■ "gHveno peiceptible difference from the air taken in Mahchefler.— 

 M. Gay-LufTac determines the conftitution of air brought from an 

 elevation of four miles to be the fame as that at the earth's fur- 

 iace, . 



fraell 



