92 



BENJ. PIKE S, JR., DESCRIPTIVE CATALOGUE. 



Fig. 549. 



main filled with steam. The open bulb is then 

 closed, by melting the glass at its capillary 

 termination. When the empty bulb is im- 

 mersed in a mixture of salt and snow, the vapor 

 existing within it is condensed, which removing 

 pressure from the surface of the water in the 

 other bulb, enables it to evaporate rapidly ; 

 and the vapor being condensed as speedily as 

 it is formed, the water is readily frozen. 



Price, $1.75. 



Fig. 550. 



Apparatus for showing Specific Heat. (Fig. 

 550.) In this arrangement there is a wooden 

 base supporting five glass tumblers, over which there is a 

 metallic frame, having a hook over each tumbler, to each of 

 which there is suspended near the bottom by a cord, a 

 metallic ball ; two of the balls are of iron, one of copper, 

 one of tin, and one of lead, each weighing exactly half a 

 pound. To use, they are to be suspended by their cords in 

 boiling water, and each will be heated to 212 degrees ; they 

 are then quickly suspended in the separate tumblers, each 

 containing exactly the same quantity of cold water, and all 

 of the same temperature. As the quantity of water and 

 the temperature in each vessel is the same, and the five 

 balls of equal weight, we should suppose that the water 

 would be equally heated, but we shall find that the lead 

 will raise the temperature the least, the tin more, the cop- 

 per more yet, and the iron most of all, each imparting a 

 different quantity of heat, except the two iron balls, which 

 will be alike. The heat imparted by each ball to the water 

 in which it is immersed is called its specific heat. 



Price, $4.00. 



