2G Formation of Ammonia, kc, 



that nitrogen had entered in some unperceived way into the ex- 

 periments, they will still shew the extreme delicacy of heat, or 

 heat and potash, as a test of its presence hy the formation of am- 

 monia. 



With respect to the delicacy of the test, it may be observed 

 that it offers many facilities to the detection of nitrogen when in 

 certain states of combination, which chemists probably were not 

 before aware of. A portion of asbestos, which had been heated 

 red hot, was introduced into a tube by metallic forceps and heated, 

 it gave no ammonia ; another similar portion compressed together, 

 and introduced by the fingers, gave ammonia when heated. A 

 very minute particle of nitre was dropped into hydrate of potassa, 

 and heated to dull redness, it gave no ammonia ; a small piece of 

 zinc foil, dropped in and the heat applied, caused an abundant evo- 

 lution of that substance. 



The circumstance also of absorption by lime and other bodies, 

 of something from inhabited atmospheres, which yields ammonia 

 when thus tested, is very interesting ; and Dr. Paris has suggested 

 to me that this power may probably be applicable to the examina- 

 tion of the atmosphere of infected and inhabited places, and may 

 perhaps furnish the means of investigating such atmospheres upon 

 correct principles. 



February, 17, 1825. 



Art. IV. — Description of the Coal recently discovered on 

 the Estates of the Count de Regla, in the Intendancy and 

 Kingdom of Mexico. By Th. Stewart Trail, M.D,> 

 F.R.S.E., 8^G. 



[Communicated in a Letter to Mr. Swainson.] 



The mineral treasures now laid open to the skill and enterprise 

 of British adventurers in South America, are daily exciting an 

 increased interest throughout the kingdom. And as connected 

 with the powerful machinery that will be employed in these un-' 



