CRUDE DRUGS. 423 



The adulterations, substitutions and sophistications will be 

 considered under the respective drugs. 



The Valuation of Drugs. — In the identification of vegetable 

 drugs certain characters are taken into account, such as color, 

 odor, general appearance, structure, texture, etc., these at the 

 same time indicating in a greater or less degree the qualitative 

 value of the drug. While these characters may enable the expert 

 to detect very slight variations in quality, and to estimate approx- 

 imately the value of a given drug, still the true value is based upon 

 the amount of the medicinal principles or so-called active con- 

 stituents. The methods employed in the valuation of drugs may 

 be grouped- as follows: (i) Chemical, (2) Physfpal, (3) Micro- 

 scopical, and (4) Biological. '-r^ 



(i) Chemical methods are more generally employed and 

 usually invblve the isolation and estimation of the active principles. 



(2) Physical methods involve such processes as the deter- 

 mination of specific gravity of the dtug, as of jalap, or the deter- 

 mination of the elasticity or measurement of the fibers, as of 

 cotton, and still other special methods which apply to individual 

 drugs, showing indirectly their quality. 



(3) Microscopical methods of valuation may oftentimes be 

 employed when other methods fail, as, for example, when foreign 

 starches are added to starchy products, as the cereals and spices. 

 Microchemical reactions may also be depended upon in some 

 instances to indicate the value of a drug, as in strophanthus, where 

 the quality of the drug appears to bear a direct relation to the 

 number of seeds giving a green coloration with sulphuric acid. 

 The separation of the salts of the alkaloids in hydrastis on the 

 addition of sulphuric acid is also of value in determining the 

 quality of this drug. 



(4) Biological methods involve the consideration of the efifects 

 of drugs upon animals or plants. They may be conveniently 

 grouped as follows : i. Effects or influence upon animals, includ- 

 ing (a) those dependent upon the perceptions or senses of the 

 experimenter or tester, as color, taste and odor; (b) those which 

 are physiological or pathological. These are usually determined 

 by experiments upon lower animals, as insects, frogs, rabbits, 

 guinea pigs, fowls, and even upon man. 2. The effect or influence 



