22 



Carbonization. — This is the process of heating organic sub- 

 stances under the exclusion of air. Its object is to change the 

 chemical composition without oxidation. (Charcoal) . 



Ignition. — This is the process of strongly heating a substance, 

 usually in a crucible, with full access to air, so as to complete oxida- 

 tion. Nothing but ashes is left. 



ToBBEPACTioN. — This means roasting. The object is to employ 

 sufficient heat to alter some of the constituents without affecting 

 others. Coffee, peanuts. 



Evaporation. — This consists in vaporizing a solvent from a 

 solution. The object is concentration of the desired dissolved sub- 

 stance. 



Solution. — This may be defined as the process of incorporat- 

 ing a solid into a liquid state of molecular subdivision, the result be- 

 ing a clear homogeneous fluid. In this case the molecules of the 

 solid are diffused throughout the liquid, and are so widely sepa- 

 rated that no solid particles are in any way discernable. In other 

 words;, the solid is liquified, and its molecules intermingle with 

 those of the liquid, (solvent). Solutions may be classified as 

 simple, chemical, unsaturated, saturated, and supersaturated. A 

 simple solution is one occurring as described above. No chemical 

 change is made. A chemical solution where chemical action takes 

 place. Unsaturated where the solvent contains less of the 

 substance than it will dissolve. Saturated when it contains all 

 that it will dissolve, and supersaturated when some means is em- 

 ployed to make the liquid dissolve more of the substance than the 

 usual amount of the solid. Example, heat in most cases, or hydro- 

 chloric acid with corrosive sublimate. 



The process of solution is applied to most organic drugs for the 

 purpose of separating the active ingredients from the insoluble 

 inert. The otoject is to dissolve the greatest amount of solid with 

 the least possible liquid, (menstruum). It accomplishes two pur- 

 poses. 1. It gives a strong extract and (2) wastes no menstruum. 

 Solution may be employed in various ways. All are combinations 

 of two extremes, maceration and percolation, usually in the United 

 States of both. 



