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



SECTION VII. 



The effects of the mercurial powder, in the last experiments, 

 made me believe that it might be confined, during its explosion, 

 in the centre of a hollow glass globe. Having therefore pro- 

 vided such a vessel, 7 inches in diameter, and nearly half an 

 inch thick, mounted with brass caps, and a stop cock, (see Plate 

 VIII.) I placed 10 grains of the mercurial powder on very thin 

 paper, laid an iron wire 149th of an inch thick across the 

 paper, through the midst of the powder, and, closing the paper, 

 tied it fast at both extremities, with silk, to the wire. As the 

 inclosed powder was now attached to the middle of the wire, 

 each end of which was connected with the brass caps, the 

 packet of powder became, by this disposition, fixed in the centre 

 of the globe. Such a charge of an electrical battery was then 

 sent along the wire, as a preliminary experiment* had shewn 

 me would, by making the wire red-hot, inflame the powder. 

 The glass globe withstood the explosion, and of course retained 

 whatever gases were generated: its interior was thinly coated 

 with quicksilver in a very divided state. A bent glass tube was 

 now screwed to the stop-cock of the brass cap, which being 

 introduced under a glass jar standing in the mercurial bath, the 

 stop-cock was opened. Three cubical inches of air rushed out, 

 and a fourth was set at liberty when the apparatus was removed 

 to the water-tub. The explosion being repeated, and the air all 

 received over water, the quantity did not vary. To avoid an 

 error from change of temperature, the glass globe was, both 

 before and after the explosion, immersed in water of the same 



* With Mr. Cvthbertson's electrometer. 



