fjS On a new fulminating Mercury, 



I procured two blocks of wood, very nearly of the fame Cze and ftrength, and bored 

 them with the fame inftrument to the fame depth. The one was charged with half an 

 ounfce of the beft Dartford gunpowder, and the other with half an ounce of the mercurial 

 powder; both were alike buried in fand, and fired by a train communicating with the 

 powders by a fmall touch-hole. The block containing the gunpowder was fimply fplit 

 into three pieces : that charged with the mercurial powder was burft in. every diredtion, 

 and the parts immediately contiguous to the powder were abfolutely pounded, yet the 

 whole hung together, whereas the block fplit by the gunpowder had its parts fairly 

 Ceparated. The fand furrounding the gunpowder was undoubtedly the moft difturbed ; in 

 fhort, the mercurial powder appeared to have a£ted with the greateft energy, but only 

 within certain limits. 



SECTION VII. 



The effeiSts of the mercurial powder, in the laft experiments, made me believe that it 

 might be confined, during its explofion, in the centre of a hollow glafs globe. Having 

 therefore provided fuch a veflel, 7 inches in diameter, and nearly half an inch thick, 

 mounted with brafs caps, and a ftop cock, (fee Plate VII.) I placed lO grains of the mer- 

 curial powder on very thin paper, laid an iron wire 149th of an inch thick acrofs the 

 paper, through the midft of the powder, and, clofing the paper, tied it fall at both ex- 

 tremities, with filk, to the wire. As the inclofed powder was now attached to the middle 

 of the wire, each end of which was connefted with the brafs caps, the packet of powder 

 became, by this difpofition, fixed in the centre of the globe. Such a charge of an eleclrical 

 battery was then fent along the wire, as a preliminary experiment* had fhewn me would, 

 by making the wire red-hot, inflame the powder. The glafs globe withftood the explofion, 

 and of courfe retained whatever gafes were generated ; its interior was thinly coated with 

 quickfilver in a very divided ftate. A bent glafs tube was now fcrewed to the ftop-cock of 

 the brafs cap, which being introduced under a glafs jar {landing in the mercurial bath, the 

 ftop-cock was opened. Three cubical inches of air rulhed our, and a fourth was fet at 

 liberty when the apparatus was removed to the water-tub. The explofion being repeated, 

 and the air all received over water, the quantity did not vary. To avoid an error from 

 change of temperature, the glafs globe was, both before and after the explofion, immerfed 

 in water of the fame temperature. It appears therefore, that the ten grains of powder, 

 produced four cubical inches orily of air. 



To continue the comparifon between the mercurial powder and gunpowder, 10 grains of 

 the beft Dartford gunpowder were in a fimilar manner fet fire to in the glafs globe : it 

 remained entire. The whole of the powder did not explode, for fome complete grains 

 were to be obferved adhering to the interior furface of the glafs. Little need be faid of 

 the nature of the gafes generated during the combuftion of gunpowder : they muft have 



• With Mr, Cuthbeitfon's eleOromctcr, 



been, 



