1 74 Mr. Graham's Account of M. Longchamp's Theoi^ 



fluence can be attributed here to the decomposition and pu- 

 trefaction of animal substances in contact with the air. 



But nitric acid forms in the open air, and in materials which 

 contain no vestige of animal or vegetable matter. An ex- 

 periment is related by one of the competitors for the French 

 prize *, in which a quantity of earth from the fields, Avashed 

 with great care, dried by exposure to the sun, and afterwards 

 kept moist by occasional watering for a year, afforded by lixi- 

 viation a saline solution, in one case of one degi'ee of the areo- 

 meter, and in another of half a degree. Thouvenel, too, 

 who has produced nitric acid by exposing chalk to the gases 

 evolved from the putrefaction of animal or vegetable substances, 

 mixed with common air, likewise obtained this acid when the 

 chalk was in contact with nothing but atmospheric air t. It 

 is true that in the experiment which he relates, the materials 

 exposed to the atmospheric air loaded with putrid gases, 

 yielded fifteen parts of nitrate of lime ; while those which were 

 in contact with pure atmospheric air, afforded no more than 

 six parts of the salt. Thouvenel concludes, " It is demon- 

 strated by our experiments, that atmospheric air possesses all 

 that is necessary to serve for nitrification, as well as the air 

 which emanates from putrescent bodies, provided it finds mat- 

 ter capable of absorbing the materials :|:." 



M. Longchamp having thus shown how ill-founded the pro- 

 position is, that the materials proper for nitrifying never ni- 

 trify in the air, without the concurrence of animal matter, at- 

 tempts, in the next place, to prove that the nitric acid is formed 

 exclusively fi'om the elements of the atmosphere. 



It is admitted, he observes, that the animal matters do not 

 requii-e to be in contact with the earths, but that their emana- 

 tions are sufficient for the production of nitre. Could it be 

 through the instrumentality of azote, which animal matter 

 mio-ht disengage during putrefaction? But chemists know 

 that the products of this putrefaction are ammonia, carbonic 

 acid, carburetted hydrogen, and perhaps some carbonic oxide 

 and water, but no azote ; and even if this gas were produced, 

 how would it combine with the carbonate of lime? There 

 are instances of extraordinary combinations of gases in the 

 nascent state, but the azote is not presented in that state in 

 the case referred to, since the putrescent blood was at the di- 

 stance of two feet from the carbonate of lime, which it is pre- 

 tended that it nitrified §. Might 



• Memoires Etrangeres dc V Academic des Sciences, xi. P. I. pag. 160. 

 t Ibid. P. II. pag. 124. X Ibid. pag. 89, 



6 The commissioners of the Academy, among whom was Lavoisier, took 



a quantity 



