326 Mr. Thompson’s Experiments 
better fuccefs. Every thing I mixed with the powder, inftead 
of increafing, ferved to ieffen the force of the charge. 
Thefe trials were all made feveral months before I began the 
courfe of my experiments upon gun-powder, which I have 
already given an account of ; and though they were altogether, 
un fuccefs ful, yet I refumed the inquiry at that time, and made, 
feveral new experiments, with a view to find out fomething 
that ihouid be ftronger than, powder,, or which, when mixed, 
with it, fhould increafe its force. 
It is well known, that the elaftic force of quickfilver con- 
verted into vapour is very great ; this fubftance I made ufe of 
in my former trials, as I have juft obferved, but without fuQ-. 
cefs. I thought, however, that the failure of that attempt 
might poffibly be owing to the quickfilver being tpo much in a, 
body, by which means the fire could not aft upon it to the. 
greateft advantage ; but that if it could be divided into exceed-, 
ing fmall particles, and fo ordered that each particle might be. 
completely furrounded by, and expofed to, the action of the. 
flame of the powder, it would he very foon heated, and poffibly , 
might be converted into an elaftic fteam or, vapour, before the. 
bullet could be fenfibly removed from its place. , To determine, 
this point I mixed 20 grains, of aethiops mineral very intimately 
with 145 grains of powder, and charging the piece with this,, 
compound, it was loaded with a fit bullet and fired; but the. 
force of the charge was lefs than that which the powder alone, 
would have exerted, as appears by comparing the. 76th and 77th 
experiments with the 79th.. 
Common pulvis fitlminans is made of one part of fulphur,, 
two parts of fait of tartar, and three parts of nitre ; and if wee 
may judge by the report of the explofion, the elaftic force of 
this compound is confiderably greater than that of gun-powder.. 
I was. 
