172 Mr. Graham's Account of M.. Longchamp's 2^heory 



what it was before found to be by calculating from Unst and 

 Stockholm on the other side*. 



I confine myself to these observations which must stand as 

 long as any trust can be put in the rules of arithmetic. To 

 venture upon any discussion concerning the cause of the sin- 

 gular discordance between Captain Sabine's experiments and 

 those made by other observers, might possibly stir up an al- 

 tercation of no pleasant kind. 



Feb. 5, 182/. J. IvoRV. 



XXXVII. An Account o/'M. Longchamp's Theory of Nitrifi- 

 cation; with a7i Extension of it. By Thomas Graham, M.A. 



To the Editors of the Philosophical Magazine a7id Annals of 

 Philosophy. 

 Gentlemen, 



IV/r LONGCHAMP, in a memoir read some time ago be- 

 ^^^' fore the Academy of Sciences, and published lately in 

 xheAnnales de Chimie et dePkysiqiie, (t. xxxiii. p. 1.) has deve- 

 loped a theory of the natural production of nitre in various 

 soils, and superficially upon certain rocks. This theory, in its 

 full detail, is, perhaps, not altogether new; for several of the 

 opinions of which it consists have been advocated, or at least 

 broached, by preceding chemists. But M. Longchamp has 

 certainly the merit of confidently displaying these opinions in 

 their full force, and of methodizing them into a consistent 

 system. Of this theory we propose to give an account, as 

 nearly as possible in the words of the author, and to subjoin 

 certain speculations, with the view of supplying a material de- 

 ficiency in the theory of M. Longchamp. 



It may be premised that M. Longchamp confines himself 

 to the production of the acid of the native nitrous salts, and 

 very properly avoids any supposition of the production of 

 their base, previously existing as fact and reason point out 

 that it must be, and, unlike the nitric acid of these salts, inca- 

 pable of a synthetic formation. 



There is reason to doubt the original proposition of Glau- 

 ber, and which as far as regards the nitric acid has been the 

 prevailing theory to the present day, that " saltpetre is formed 

 by the decomposition of animal and vegetable substances ;" 

 for nitrates form and are found in materials and in places 

 which contain no vegetable or animal matter, and which have 

 never been exposed to the emanations of animals. 



* Phil. Mag. Oct. 18;:6, p. ^51. 



Persons 



