272 



BENJ. PIKE S, JR., DESCRIPTIVE CATALOGUE. 



hold of the frame by the other hand, at the handle or some 

 other part of the frame, and direct another person to hold 

 that part which you have just quitted with one hand, and 

 to take off the money with the other. His attempt to do 

 so will discharge the sheet of glass, and he will receive a 

 shock in the fingers, while he will be quite unable to take 

 off the money. Price, $1.75. 



Sulphur Cone. (Fig. 295, as below.) This apparatus is 

 formed from a large wine glass. This is cleaned, and a part 

 of the outside, as represented, covered with tin foil. A wire 

 is twisted round this covered part, and bent so as conve- 

 niently to hold a pair of pith balls suspended on very fine 

 wires, or on linen threads. Within the glass is poured 

 melted sulphur, to about the same height, or a little above 

 the edge of the tin foil, and the end of a glass rod, or else 

 of a silk cord, dropped into the sulphur while melted. 



Fig. 296. 

 Fig. 295. 



To use, lift up by the glass handle, the sulphur within 

 the conical glass, and, at the moment of separation, the pith 

 balls will diverge, or separate from each other. Let the 

 sulphur drop down again into the glass, and this action of 



