CHEMICAL APPARATUS. 



91 



pared is filled with alcohol, and the lamp lighted, which 

 will heat the wire red hot if properly arranged ; blow the 

 flame out, and the wire will continue red hot as long as any 

 alcohol remains in the lamp. Price, $1.25. 



Fig. 547. 



Pulse Glass. (Fig. 547, as above.) A little instrument 

 to show the effects of heat. It consists of a small glass 

 tube, with a bulb at each end, and partly filled with colored 

 spirits of wine, the space above the spirit being -void of air. 

 When this tube is held in the hand obliquely, a small bubble 

 of air remaining in the lower ball, the heat of the hand 

 will expand the air in this bubble, and its escaping into the 

 vacant space above with a pulsatory motion occasions the 

 instrument to be called a pulse glass, though it has no 

 reference to the state of the pulse. Price, 50cts. 



Boiling Glass. If the 

 glass be made in the shape 

 of the annexed tube, the 

 liquid will appear to boil 

 rather than rise in pulsations. 



Fig. 548. 



Price, 50 cts. 



Chryopherus. (Fig. 549.) An instrument for illustrating 

 the effect of evaporation in producing cold. It consists of a 

 glass tube, from 18 inches to 2 feet in length, having an in- 

 ternal diameter of one-fourth of an inch. The tube is bent 

 at right angles near the ends, both of which are terminated 

 by bulbs, as in the above figure ; or bent at one end only, as 

 represented in Fig. 549, next page, which is the strongest 

 and preferable form. In constructing this instrument, one 

 of the bulbs is nearly filled with water, which being made to 

 boil, the air is expelled from the tube and bulbs, which re- 



