^4 Cbemijlry. 



diatefy commenced, and oxygenous and nitrous air was dir- 

 charged; the latter holding a portion of the copper in folu- 

 tion, as appeared by immerfing a lighted taper in the nitrous 

 acid gas, when it burned with an enlaro-ed vivid and blue 

 flame. The flame of the taper was frequently blown out, 

 and rekindled by dipping it into the air. 



Some concentraled nitric acid was alfo poured upon tin 

 foil, when it remained in a quiefcent ftate for the fpace of 

 one week ; but, upon the addition of water, the whole was 

 inftantaneoufly converted into a white oxyd, with the pro- 

 duftion of a high degree of heat. 



The errors of chemifts, in regard to the a6lion of nitric 

 aeid upon tin, will be fcen more clearly by extracting wliat 

 has been faid upon the fubjeft. 



Chaptal tells us the nitric acid devours tin, that the de- 

 compofition is fpeedy, and that the metal is inftantly preci- 

 pitated in the form of a white oxyd. The fame author fays, 

 Mr. Baume even pretends that the nitric acid does not dif- 

 folve tin ; but Kunckel and the famous Rouellc have main^ 

 tained the contrary. 



Fourcroy declares that tin dccompofes nitric acid, even in 

 the cold, with amazing rapidity, and that this is one of the 

 mod aftonifliingly rapid folutions in all chcmidry. 



From what has been faid, it appears that Mr. Baume is 

 right, and that Fourcroy, Chaptal, Rouelle, and Kunckel, 

 ufcd an acid diluted with water. 



In vi'hat manner does water aft in thefe experiments ? 



Dr. Prleltley fuppofes that no air can be produced without 

 water, and that it is necelTary to the contlitution of every 

 kind of air : but this throws little light upon the fubjedt, and 

 It does not account for the manner in which water afts in 

 promoting the folutlon of filver, copper, and tin, in the nitric 

 acid ; and nitrous air may be obtained from zinc and bifmuth 

 by the acid, however concentrated. 



It may be fuppofed that the water merely produces heat 

 by uniting with the acid, and fo dlflblves the metals ; but 

 this is not the cafe ; for, if the acid is diluted with water. 

 And (lands until it is cool, it will fpeedily diifolve them. 



It 



