650 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 



acid had been formed, and united to the mercurial oxide. I therefore, for obvious 

 reasons, poured sulphuric acid on the dried crystalline mass, when a violent effer- 

 vescence ensued, and, to my great astonishment, an explosion took place. The 

 singularity of this explosion induced me to repeat the process several times ; and 

 finding that I always obtained the same kind of powder, I prepared a quantity of 

 it, and was led to make the following series of experiments. 



§ 3. I first attempted to make the mercurial powder fulminate by concussion; 

 and for that purpose laid about 1 gr. of it on a cold anvil, and struck it with a 

 hammer, likewise cold : it detonated slightly, not being, as I suppose, struck with 

 a flat blow ; for, on using 3 or 4 gr., a very stunning disagreeable noise was pro- 

 duced, and the faces both of the hammer and the anvil were much indented. 

 Half a grain or 1 gr., if quite dry, is as much as ought to be used on such an 

 occasion. The shock of an electrical battery, sent through 5 or 6 gr. of the pow- 

 der, produces a very similar effect: it seems indeed that a strong electrical shock 

 generally acts on fulminating substances like the blow of a hammer. Messrs. 

 Fourcroy and Vauquelin found this to be the case with all their mixtures of oxy- 

 muriate of pot-ash.* 



To ascertain at what temperature the mercurial powder explodes, 2 or 3 gr. of 

 it were floated on oil, in a capsule of leaf tin ; the bulb of a Fahrenheit's thermo- 

 meter was made just to touch the surface of the oil, which was then gradually 

 heated till the powder exploded, as the mercury of the thermometer reached the 

 368th degree. 



§ 4. Desirous of comparing the strength of the mercurial compound with that 

 of gunpowder, I made the following experiment, in the presence of my friend 

 Mr. Abernethy. Finding that the powder could be fired by flint and steel, with- 

 out a disagreeable noise, a common gunpowder proof, capable of containing 1 1 gr. 

 of fine gunpowder, was filled with it, and fired in the usual way: the report was 

 sharp, but not loud. The person who held the instrument in his hand felt no 

 recoil ; but the explosion laid open the upper part of the barrel, nearly from the 

 touch-hole to the muzzle, and struck off the hand of the register, the surface of 

 which was evenly indented, to the depth of 0.1 of an inch, as if it had received 

 the impression of a punch. — The instrument used in this experiment being famili- 

 arly known, it is therefore scarcely necessary to describe it; suffice it to say, that 

 it was of brass, mounted with a spring register, the moveable hand of which 

 closed up the muzzle to receive and graduate the violence of the explosion. The 

 barrel was £ an inch in caliber, and nearly -; an inch thick, except where a spring 

 of the lock impaired -^ its thickness. 



$ 5. A gun belonging to Mr. Keir, an ingenious artist of Camden-town, was 



next charged with 1 7 gr. of the mercurial powder, and a leaden bullet. A block 



of wood was placed at about 8 yards from the muzzle, to receive the ball, and the 



gun was fired by a fuse. No recoil seemed to have taken place ; as the barrel was 



* Annale de Chimie, torn. 21, p. 239. — Orig. 



