190 Miscellanies. 



portions of the substances as could vaporize, have been free to act and 

 produce accumulation of their specific effects. 



In this way it was found that neither sulphate of soda, nor muriate 

 of baiytes, were volatilized ; the same was the case with solution of 

 nitrate of silver and chloride of sodium ; diluted sulphuric acid and 

 common salt ; solution of potash and arsenious acid in pieces and 

 powder ; diluted sulphuric acid and muriate of ammonia : solution 

 of persulphate of iron and ferrocyanate of potash in crystals ; solu- 

 tion of potash and fragments of calomel ; solution of iodide of potash 

 and chloride of lead ; solution of muriate of lime and crystals of car- 

 bonate of soda ; solution of per-sulphate of copper and crystals of 

 ferro-cyanate of potash, — from these experiments it would appear, 

 Mr. Faraday observes, " that there is ho reason to believe that water 

 or its vapors confer volatility, even in the slightest degree, upon those 

 substances which alone have their limits of vaporization at tempera- 

 tures above ordinary occurrence, and that consequently natural evap- 

 oration can produce no effects of this kind on the atmosphere." 



From other experiments, Mr. Faraday concludes that " nitrate of 

 ammonia, corrosive sublimate, oxalic acid, and perhaps oxalate of am- 

 monia, are substances which evolve vapor at common temperatures." 

 (Journal of the Royal Institution, October, 1830.) — Phil. Mag: and 

 Ann. Nov. 1830. 



13. Composition of gunpowder. — Dr. Ure has analyzed various 

 samples of gunpowder, and the following are the results of his inves- 

 tigation : 



Waltham Abbey — nitre, 74.5 ; charcoal, 14.4 ; sulphur, 10. ; water, 

 1.1 



Hall, Dartford — nitre, 76.2 ; charcoal, 14. ; sulphur, 9.0 ; water, 

 .8 ; loss, .3 



Pigou & Wilkes — nitre, 77.4; charcoal, 13.5; sulphur, 8.5; wa- 

 ter, .6 



Curtis & Harvey — nitre, 76.7 ; charcoal, 12.5 ; sulphur, 9. ; water, 

 1.1 ; loss, .7 



Battle gunpowder — nitre, 77. ; charcoal, 13.5 ; sulphur, 8. ; water, 

 .8 ; loss, .7 



" The process," observes Dr. Ure, " most commonly practised in 

 the analysis of gunpowder seems to be tolerably exact. The nitre 

 is first separated by hot distilled water, evaporated and weighed. A 

 minute loss of salts may be counted on from its known volatility, with 

 boiling water. I have evaporated always on a steam bath. It is prob- 

 able that a amall proportion of the lighter and looser constituents of 

 guupowder, the carbon, flies off in the operations of corning and dus- 



