^2'6 Mr. Thompson’s Experiments 
better fuccefs. Every thing I mixed with the powder, inftead 
of increafing, ferved to leffen 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 
unfuccefsful, yet I refumed the inquiry at that time, and made 
feveral new experiments, with a view to find out fomething. 
that fliould be ft r on ger 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 fuc-- 
cefs. I thought, however, that the failure of that attempt, 
might poftibly be owing to. the quickfilver being too much in a, 
body, by which means the fire could not ad upon it to the. 
greateft advantage ; but that if it could be divided into exceed-^ 
ing fin all particles, and fo ordered that each particle might be, 
completely furrounded by, and expofed to, the aftion of the, 
flame of the powder, it would be, very foon heated, and poffibly 
might be converted into an elaftic fleam or vapour, befoie the. 
bullet could befenfibly removed from its place. , To determine 
this point I mixed 20 grains of aethiops mineral very lntirnately 
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 tne. 76th and 77^ 
experiments with the 79th.. 
Common puhis fulminans is made of one part of fulphrny 
two parts of J fait of tartar, and three parts of nitre ; and if we 
may judge by the report of the explofion, the elaftic force of 
this compound is confiderably greater than that of gun-powder. 
I was 
