Mr. E. Howard on a new fulminating Mercury. 207 



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 

 oxymuriate of potash.* 



To ascertain at what temperature the mercurial, powder 

 explodes, 2 or 3 grains of it were floated on oil, in a capsule of 

 leaf tin ; the bulb of a Fahrenheit's thermometer was made 

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

 heated till the powder exploded, as the mercury of the thermo- 

 meter reached the 368th degree. 



SECTION IV. 



Desirous of comparing the strength of the mercurial com- 

 pound with that of gunpowder, I made the following experi- 

 ment, in the presence of my friend Mr. Abernethy. 



Finding that the powder could be fired by flint and steel, 

 without a disagreeable noise, a common gunpowder proof, 

 capable of containing eleven grains 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 familiarly 

 known, it is therefore scarcely necessary to describe it ; suffice 

 it to say, that it was of brass, mounted with a spring register, 



* Annates de Cbimie, Tom. XXI. p. 239. 



