upon Gun-powder^ &c. 32-1 
mean pretiure of the atraofphere, as will be evident to thofe 
who will take the trouble to make the computation* 
Of an attempt to determine the explofve force of aurum fulmi- 
nans, or a comp ar if on between its force and that of gun -powder • 
«Y'. . I,* cfl t I, . .wr 4/\ pj'-v'O^I r Ho f h ; '? -v* 'v - •; - 
Having provided myfelf with a fmall quantity of this won- 
derful powder, upon the goodnefs of which I could depend, I 
endeavoured to afcertain its explofive force by making ufe of it 
inftead of gun-powder for difcharginga bullet, and meafuring, 
by means of the pendulum, the velocity which the bullet ac- 
quired; and concluding, from the tremendous report with which 
this fubftance explodes, that its elaftic force was vaftly greater 
than that of gun-powder, I took care to have a barrel provided 
of uncommon ftrength, on purpofe for the experiment. Its 
length in the bore is 13,25 inches, the diameter of the bore is 
0,55 an * nc h> and its weight 7 lbs. 2 oz. It is of the bed: 
iron, and was made by wogdon ; and the accuracy with which 
it is finilhed does credit to the workman. 
This barrel being charged with one fifteenth of an ounce 
(= 27,34 grains) of aurum fulminans and two leaden bullets, 
which, together with the leather that was put about them to 
make them fit the bore without windage, weighed 427 grains ; 
it was laid upon a chaffing-difh of live coals, at the diftance of 
about 10 feet from the pendulum, and againft the center of the 
target of the pendulum the piece was diredted. 
Having feeured the barrel in fuch a manner that its diredtion. 
fhould not alter, I retired to a little diftance, in order to be out 
of danger in cafe of an accident, where I waited in anxious 
expectation the event of the explofion. 
I had 
