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ing-mills were formerly ufed for working gun-powder ; their con- 

 ftrudion was very fimplc, l)eing a large mortar, in which a pon- 

 derous wooden peftle moved by men, by horfes, or by water, 

 performed the operation very perfedly, but with obvious danger 

 to the workmen. In Sweden, and I believe in Ruffia, they ftill 

 continue to ftamp the powder during the firft part of the procefs, 

 and afterwards roll it under ftones ; by this means Icffening the 

 probability of an explofioii, as the compofition is lefs inflam- 

 mable in the beginning than when the fnaterials are more inti- 

 mately blended. Since government, alarmed by the frequency 

 of accidents, thought proper to prohibit ftamping in the ordnance 

 mills, this part of the procefs has been efFeiled by means of two 

 ftone cylinders applied to the ends of a common axis, and moved 

 in a vertical pofition round a circular trough, either by water 

 or by horfes. The inferiority of the prefent pradice is vifible in 

 its operation on the powder, which has certainly degenerated 

 both in flrength and durability fince the abolition of ftamping- 

 mills. This may be attributed, firft, to negled in the manu- 

 fa<5lurer, who is fatisfied with working his powder fcven or eight 

 hours inftead of twenty- four, which was the ufual time when 

 ftamping-mills were employed ; and, fecondly, to a radical defcd 

 in the machine, where the circumferences of two fmooth and 

 ponderous floncs comprefs the moift pafte into a hard folid cake, 

 over which they make repeated circumvolutions with a very 

 trifling derangement of the indurated furface, and confequently 

 without contributing much to the incorporation of the ingre- 

 dients. To obviate the firft objedion, it is necefl"ary that 

 government fliould ftimulatc the induftry of the merchant, by 



giving 



