ACTIVE PRINCIPLES. — The so-called active principles consist of a number of glucosides: digitalin, digitalein, dig itonin, digitin, and digitoxin. -Unfort unately, great confusion exists regarding these preparations, which has been fos tered by pharmacopccial errors. Thus the digitalin of Homolle & Quevenne, recognized by French authority, is an amorphous, yellowish-white powder, in odorous, intensely bitter to taste, ex tremely irritating to the nostrils, and highly poisonous; it is sometimes found as small scales. It is chemically a mixt ure of the digitalin of the German phar macopceia and the digitoxin of Schmiede berg. Another form that has the sanc tion also of the French Codex is digi taline (mark the final e) cristallisee, or the digitaleine of Nativelle, and appears as white, crystalline tufts or needles, and consists almost wholly of Schmiedeberg's digitoxin; it is very bitter to taste, slowly eliminated and consequently cumulative in action, and dispensed only when "crystallized digitalin" is ordered. Both the foregoing are insoluble in water or ether, but the crystallized form yields readily to chloroform and rectified spirit.
The digitalin of the German Pharma copceia is also the digitalin verum of Kiliani. It is a white or yellowish, amorphous product, consisting of digi talein and digitoxin (Schmiedeberg's); is soluble in water, 1 to 1000 in alcohol; almost insoluble in chloroform and ether.
Digitalein (Schmiedeberg) is also an amorphous, yellowish-white powder of intense bitter taste; soluble in water and alcohol, slightly so in chloroform and ether; as before remarked, this is the chief constituent of German digi talin.
DIGITOXIN.—The digitoxin glucoside Df Schmiedeberg is the most poisonous of all the digitalis principles and likewise markedly cumulative in action, owing to the difficulty with which it is eliminated. It occurs as a white, crystallized powder, soluble in chloroform and alcohol, slightly soluble in ether, insoluble in water.