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



REFERENCES TO THE FIGURES OF THE GLASS GLOBE, &C. 

 MENTIONED IN SECTION VII. 



(See Plate VIII.) 



A, a ball or globe of glass, nearly half an inch thick, and 

 seven inches in diameter. It has two necks, on which are 

 cemented the brass caps B, C, each being perforated with a 

 female screw, to receive the male ones D, E : through the former 

 a small hole is drilled ; the latter is furnished with a perforated 

 stud or shank G. By means of a leather collar H, the neck C 

 can be air-tightly closed. When a portion of the powder is to 

 be exploded, it must be placed on a piece of paper, and a small 

 wire laid across the paper, through the midst of the powder : 

 the paper being then closed, is to be tied at each end to the 

 wire, with a silken thread, as shewn at I. One end of this wire 

 is to be fastened to the end of the shank G, and the screw D 

 inserted to half its length into the brass cap B ; the other end 

 of the wire, a, by means of the needle K, is to be drawn through 

 the hole F. The screw E being now fixed in its place, and the 

 wire drawn tight, it is to be secured, by pushing the irregular 

 wooden plug L into the aperture of the screw D, taking care 

 to leave a passage for air. The stop-cock M, the section of 

 which is shewn at N, is now to be screwed on to the part D, 

 which is made air-tight by the leather collar b. The glass tube 

 O is bent, that it may more conveniently be introduced under 

 the receiver of* a pneumatic apparatus. P, shews the manner 

 of connecting the glass tube with the stop-cock. 



