When two or three drops of sulphuric acid and furfur aldehyde (5 drops to 10 c.c. of acid) are added to minute particles of alkaloids, a more or less characteristic colour makes its appearance; this is particularly the case with veratrine. A few particles rubbed with a glass rod, and moistened with the reagent, gives first a yellowish-green, then an olive-green mixture, the edges afterwards becoming a beautiful blue. On warming, the mixture gradually acquires a purple-violet colour. The blue substance obtained in the cold is insoluble in alcohol, ether, or chloroform. The least amount of water decolorises the solution, and, on adding much water, a fairly permanent yellow solution is obtained.[530]
[530] A. Wender, Chem. Zeitung, xvii. 950, 951.
§ 479. Pharmaceutical Preparations.—The alkaloid is officinal in the English, American, and Continental pharmacopœias. There is also an unguentum veratrinæ—strength about 1·8 per cent. In the London pharmacopœia of 1851 there used to be a wine of white hellebore, the active principle of 20 parts of the root by weight being contained in 100 parts by measure of the wine. Such a wine would contain about 0·084 per cent. of total alkaloids. Of the green hellebore there is a tincture (tinctura veratri viridis), to make which four parts by weight of the root are exhausted by 20 parts by measure of spirits; the strength varies, but the average is 0·02 per cent. of total alkaloids.
§ 480. Fatal Dose.—The maximum dose of the commercial alkaloid is laid down as 10 mgrms. (·15 grain), which can be taken safely in a single dose, but nothing sufficiently definite is known as to what is a lethal dose. 1·3 grm. of the powdered rhizome has caused death, and, on the other hand, ten times that quantity has been taken with impunity, so that at present it is quite an open question.
§ 481. Effects on Animals—Physiological Action.—Experiments on animals have proved that the veratrums act on the sensory nerves of the skin, and those of the mucous membranes of the nose and intestinal canal; they are first excited, afterwards paralysed. When administered to frogs, sugar and lactic acid appear in the urinary excretion.[531] It exercises a peculiar influence on voluntary muscle; the contractility is changed, so that, when excited, there is a long-continuing contraction, and from a single stimulus more heat is disengaged than with healthy muscle; the motor nerves are also affected. The respiration, at first quickened, is then slowed, and finally paralysed. The heart’s action is also first quickened, the blood-pressure at the same time is raised, and the small arteries narrowed in calibre; later follow sinking of the pressure, slowing of the heart, and dilatation of the vessels, and the heart becomes finally paralysed.
[531] Zeit. Phys. Chem., xvi. 453-459.