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however, on chymical principles, we fhould prefer that made 

 from wood containing the greateft quantity of lix^fd fults, and 

 whofe afhes abound with alkaline falts, as fuch inflames more 

 rapidly and burns %vith greater vehemence. Dogwood (cornus- 

 fcsminea, virga fanguinea) and alder (alnus nigra, baccifera) 

 are efteemed by powder-makers the fitteft for their charcoal ; 

 but I have not been able to difcover any cogent reafon for 

 this preference. Green wood being harder when charred Lhan 

 dry, I believe admits of a more complete comminution, and is 

 confequently better adapted to that intimate combination of the 

 ingredients neceffary for the flrength and durability of gun- 

 powder. I am informed of an improved method lately dif- 

 covered for the preparation of charcoal ; it is a kmd of oven, 

 which admitting the external applicaiion of heat, the wood 

 piled within is more equally charred and its volatile parts more 

 completely evaporated. 



Experience has convinced me that it is of the utmoft impor- 

 tance to give an exad attention to the purity of fulphur, the third 

 ingredient in the compofition of gun-powder. On this agent de- 

 pends that rapidity of inflammation, to which the charcoal con- 

 tributes intenfe fire, and the nitre its altonifhing elaflicity and 

 expanfion. 



A MANUFACTURER of gun-powder ought never to ufc ful- 

 phur which he has not purified and fublimed himfelf : the befl 

 method of doing this is by melting it in an iron pot over a 

 gentle coal fire which does not blaze, and flraining it through 

 a double, linen cloth ; the operation mufl be repeated till there 

 appears httle or no refiduum. When fulphur is bought in a 



prepared 



