4t4 ■^^'f ProduBion of Nitrous Acid:— -Of the C^yfo/ke. 



■which this oxide always contains in its native ftate. While the gas was extricated in great 

 abundance, one of the cocks pf the tube through which the gas pafled was accidentally 

 opened, fo that a portion of the gas, very hot and pure, was emitted into the atmofphere. 

 At the fame inftant all the affiftants were furprifed by a manifeft fmell o£ nitric acid, and 

 a flight fume was fccn to rife from the place whence the gas had iffued. 



Profeffor Piftet, who was prefent, firli: took notice of the fingularity and importance of 

 this fafl:. It appears to prove, that when hot and very pure oxygen is brought into contaft 

 with the atmofpheric air at the ordinary temperature, nitric acid is formed by the chemical 

 combination of the two-conftituent pxLnciples of that acid ; fo that by caufing pure and hot 

 oxygen gas. on the one hand, and qtmofpheric air on the other, to pafs into a glafs globe 

 or any other clofc veffiil, a great quantity of nitric acid gas would be obtained, which might 

 be condenfed and abforbtd by water previoufly put into the vefiel. Again, it is known that 

 nianganefe has the property of abforbing the oxygen of the air, or of water, when deprived 

 of ito original portion by mer.ns of fire. It might therefore be pra£licable, by means of a 

 determinate quantity of t;he black oxide of manganefe, to obtain fucceflively from the at- 

 mofpheric air itfelf an unlimited quantity of nitric acid, which would befides have the ad- 

 vantage of being perfeflly pure, if care was taken to purify the atmofpheric air made ufe of 

 in the operation 



* 



w> 



IX. 



Attalyfis of the Chryfollte of the Jewellers, proving it to be Phofphate of Lime. 

 By Citizen Vav^ELIN\. 



H E N I frequently heard from the mouth of Fourcroy, in his leftures during the 

 laft ten years, and repeated in my memoir on the new metal contained in native red lead, 

 that, if the art of the chemifl could be exercifed upon the objects of natural hiftory 

 preferved in colleftions, difcoveries would often be made of much utility to the advance- 

 ment of that fcience ; I did not expeft that I fhould have fo fpeedy an opportunity of 

 •evincing the truth of that obfervation to the Inftitute. 



Naturalifts have hitherto confidered the chryfoJite as a precious fione of the fecond 

 order, and all writers have arranged it at the end of thf gems properly fo called. Citizea 

 Lametherie, in his Manuel du Mineralogifte, placed it immediately after the emerald and 

 the aqua marine ; Citizen Sage, in his Chemical Analyfis, has ranged k with the faphir ; 



* This faft appears to d^er.-e the notice which the Author and tfe worthy Genevan Profeffor have be- 

 llowed upon it, and is certainly entitled to farther invcftigation. In order that the fpeculations at the end of 

 the paper may be admitted or refuted, it appears necell'ary to determine, whetlier the claftic t5uid which ef- 

 eapod was pur^ oxygeir, orwas contajninated With nitric acid. Thismiglithavebeen ^fc^rtaVBcAby examining 

 the water over which the gas was coUefted. As.t.he native.o.xide of manganefe contains azote, which, as Fourcroy 

 informs us, is driven over, for the moft part, before the ignition; and as Milner and Cavendilh have fliewn 

 that nitrous acid is formed by the combination of oxygen andasote at a red heat) there feems to be fome ground 

 for fufpicion, that the nitrous acid in tlie cafe before us was formedby a remaining portion of azote in the man- 

 ganefe after the ignition took plgce-^rN; 



f Read to the firft clafs .of the National Inftitute of Eiance, in Brumaire,iin the year VI. (Nov. i797f^ 

 It is infened in the Annales de Chimic, xxvi, 123. I have added the words in the title exprelfiiig the com- 

 jonent parts of this ftone.. N. 



