74 PHARMACY 



Clarification. — Is the process whereby cloudj substances 

 are made clear by the addition of some coagulable sub- 

 stances, as albumin or ichthyocoUa. It is the adding to any 

 fluid, containing a sediment, a substance which will carry 

 down all undissolved particles, then filtering or decanting 

 the liquid. 



CHEMICAL PROCESSES USED IN PHARMACY. 



Solution. — The process by which soluble substances 

 assume the fluid state through the action of a liquid. 



Lixiviation. — Employed to separate a soluble constituent 

 from an insoluble porous body. The substance to be lixi- 

 viated is mixed with water and placed in a conical vessel, 

 the bottom of which is covered with straw or coarse sand, 

 and, after maceration has continued sufficiently, the satu- 

 rated portion, called the lye, is drawn off from an opening in 

 the lower part of the vessel. 



Crystallization. — Is the concentration of a liquid con- 

 taining a soluble solid by means of heat, when on allowing 

 it to stand until cool, crystals form. Stirring during cooling 

 will produce granulation. Solution, filtration and crystalliza- 

 tion are the three best ways of obtaining pure salts. 



PROCESSES REQUIRING THE APPLICATION OP HEAT. 



Liquefaction. — Is the melting of substances which at 

 ordinary temperature are hard, and when cool return to the 

 same condition as before heating, as resin, wax, lard, tallow. 



Evaporation. — Is the conversion of a liquid into steam 

 or vapor. Liquids which evaporate at ordinary tempera- 

 ture are called volatile, as alcohol. To keep the heat 

 below the boiling point of water, we use the water bath, 

 which cannot reach a higher temperature than 100° C. To 

 gradually increase the heat, use the sand bath. 



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