642 BOTANY AND PHARMACOGNOSY. 



I. Solid. — Continued. 



I. In irregular masses composed of matrix and tears. 



Whitish tears, matrix yellowish-brown or 

 brownish-gray, odor alliaceous Asafetida 



Yellowish-brown tears, matrix reddish-brown, 

 odor balsamic Benzoinum 



K. In masses composed of tears. 



Brownish-red or yellowish-brown, balsamic Myrrha 



Yellowish, terebinthinate Terebinthina 



II. Liquid or Semi-Liquid. 



Blackish-brown, empyreumatic and terebinthinate Fix Liquida 



Grayish, balsamic Styrax 



Pale yellowish, transparent, terebinthinate. .Terebinthina Canadensis 



AMYLUM.— STARCH.— The starch grains obtained from 

 the grains of wheat (Triticum sativum and its varieties), corn 

 (Zea Mays, p. 228) and rice {Oryza sativa) (Fam. Gramineae). 

 The grains are separated from the cells, purified in various ways, 

 and subsequently washed with large quantities of water. In the 

 U. S. Pharmacopceia corn starch alone is recognized. 



In the preparation of corn starch the corn grains are softened 

 by being placed in running water and kept at a temperature of 

 about 60° C. for several days, care being taken to prevent any 

 fermentation. The grains are then crushed between burr-stones 

 and the paste carried by means of water to large sieves, the 

 strained magma then being reground and carried to sieves made 

 of bolting cloth. The milky-fluid containing the starch is then 

 run into settling vats, the starch separating out. The starch 

 is then freed from oil, albuminoids and other substances by treat- 

 ing it with a 15 per cent, solution of caustic soda. The super- 

 natant liquid is removed and the starch washed with water to 

 remove all traces of alkali. The starchy mixture is allowed to 

 stand, when the starch separates out and is dried. Commercial 

 starch is likely to contain some free alkali, which is readily 

 detected by the addition of an aqueous solution of fuchsin, which 

 becomes decolorized immediately in the presence of a starch con- 

 taining free alkali. 



