\PIS MELLIFICA. 



to the fingers, or to the teeth when it is chewed, acquires 

 tenacity when heated, melts at 142, and burns entirely 

 away. Its specfiic gravity varies from 0.9600 to 0.9650. 



Wax in this form is often adulterated with earth, or resin 

 and tallow. Earth may be suspected when the cake is very 

 brittle, and the color inclines more to gray than bright pale- 

 yellow ; they may be separated by melting and straining the 

 wax. The presence of resin may be suspected when the 

 fracture appears smooth and shining, instead of being gran- 

 ulated, and it may be detected by putting small pieces of 

 the wax in cold alcohol, which will readily dissolve the resin- 

 ous part, without acting on the real wax. Tallow is discov- 

 ered by the greater softness and unctuosity of the cake, and 

 its disagreeable, suffocating smell when melted. 



Yellow wax is scarcely ever ordered as medicine for inter- 

 nal use, although its coloring matter does not affect its 

 medical properties. It is chiefly employed in the composition 

 of external applications. 



CERA ALBA. Bleached wax, or white wax. When yellow 

 wax is exposed, with an extended surface, to the action of 

 light and air, and sprinkled with water, the yellow color and 

 peculiar odor are lost, and it becomes white. This process 

 is thus performed. The yellow wax is melted with a very little 

 water in a copper vessel, and then run off through a plug- 

 hole in the bottom into another vessel, which is covered with 

 a cloth to retain the heat until the water and the impurities 

 settle. The clarified melted wax is next suffered to flow into 

 a vessel, the bottom of which is full of small holes, through 

 which it runs in small streams upon a cylinder kept constant- 

 ly revolving over, and partly dipping in, cold water, into which 

 the wax falls drawn out into thin shreds or ribbons, and is 

 instantly cooled. These are spread upon cloths stretched on 

 frames exposed to the light and air, and occasionally watered 

 and turned, so that after some days the color nearly disap- 

 pears. After being thus half bleached, the wax remains 

 heaped up in a solid mass for a month, when the whole pro- 

 cess is again repeated. It is, lastly, generaUy melted and cast 

 into thin discs, about five inches in diameter, in which form 

 it is found in the stores. 



White wax is sometimes adulterated with white oxide of 

 lead, in order to increase its weight, with white tallow, and 

 with potato-starch. The first is detected by melting the wax 



17 



