140 Dr. lire on Gunpowders 



Captain Vergnaud's charge is groundless. The superiority of 

 our sporting gunpowders is due to the same cause as the supe- 

 riority of our cotton fabrics the care of our manufacturers in 

 selecting the best materials, and their skill in combining them. 



7. On Detonating Matches. 



This subject has been so ably treated in the report of MM. 

 Aubert, Pellissier, and Gay Lussac, that I shall confine myself 

 to a few observations, the results chiefly of my own experience. 

 Mr. Howard's proportions of the ingredients for preparing 

 his fulminate of mercury are, 



Mercury . . . .100 Grains. 



Nitric acid, sp. gr. 1.3, 1 measured ounces = 884 

 Strong alcohol, 2 measured ounces . =750 



The mercury is dissolved by heat in the acid, the solution is 

 allowed to cool to a blood-heat, and then 4 poured into the 

 alcohol. On heating the mixture slightly, an effervescence 

 soon ensues, the commencement of which is the signal for re- 

 moving the heat from the matrass or retort ; for if it be con- 

 tinued for some time longer, the chemical action will become 

 furious, and the fulminate will be injured by an admixture of 

 subnitrate of mercury. After the crystalline powder precipi- 

 tates, the whole is to be thrown on a filter, washed, and dried 

 on a steam-bath. 



The authors of the above report say the best proportions 

 are those of Howard ; but they appear to estimate them 

 incorrectly, for they prescribe 12 of nitric acid and 12 of alco- 

 hol (by weight) to 1 of mercury. We may hence infer that 

 considerable latitude may be used in the proportions of the 

 materials. I consider the latter ones wasteful, since 100 of 

 mercury, with 950 of nitric acid, 1.35 and 850 alcohol 0.835, 

 produce about 120 parts of a perfect fulminate. The super- 

 natant liquid retains nearly 5 per cent, of the mercury, for 

 5 grains of a dark-grey oxide may be obtained from it by 

 ammonia. 



I have analyzed the match-powder collected from fifty deto- 

 nating caps of French manufacture, taken from a stock found 

 to answer very well in practice. The whole weighed exactly 



