368 POISONS : THEIR EFFECTS AND DETECTION. [§ 435. 
with 20 millilitres of water, and titrate back with N/20 solution of sodium 
hydroxide, tincture of cochineal being used as indicator. Deduct the 
number of millilitres of the alkaline solution from 5 ; multiply the differ¬ 
ence by 0-3217 ; the result will be the percentage of ether-soluble alkaloids 
in the powdered root. 
The behaviour of a sample of Merck’s aconitine, m.p. 184°, in the 
subliming cell was as described at page 262. 
Aconitine dissolves in water at 22° in the proportion of 1 in 4431 
( Dunstan) ; it is soluble in 37 of absolute alcohol, 64 of anhydrous ether, 
5-5 parts of chloroform and benzene (A. Jurgens) ; it has basic pro¬ 
perties, and a cold watery solution has an alkaline reaction to cochineal, 
but not to litmus nor to phenolphthalein. Aconitine is not precipitated 
by mercuric potassium iodide, but gives a voluminous precipitate with 
an aqueous solution of iodine in potassium iodide, and a crystalline com¬ 
pound with gold chloride. 
The alkaloids of aconite are extracted from the root or from organic 
matters on the lines laid down in the B.P. for the assay of the root. 
Official Tests for Aconitine. —The characters and tests for aconitine 
are described as follows in the-B.P. :—Colourless, transparent, hexagonal 
crystals belonging to the rhombic system, prismatic and tabular; melting- 
point 198°, at which temperature evolution of acetic acid occurs. 
Almost insoluble in water, petroleum spirit, and carbon disulphide ; 
readily soluble in benzene and chloroform, less readily in ether and in 
absolute alcohol. Forms a crystalline hydrochloride which melts at 149^. 
A drop of an aqueous solution (1 in 10,000) placed upon the tongue pro¬ 
duces a characteristic tingling and numbing sensation. An aqueous 
solution not more dilute than 1 in 4000, faintly acidified with acetic acid, 
yields a reddish precipitate on the addition of a few drops of N/10 
solution of potassium permanganate. The ethereal solution obtained 
by boiling aconitine with N/2 alcoholic solution of potassium hydroxide, 
removing most of the alcohol by evaporation, diluting with water, acidify¬ 
ing and extracting with ether, leaves on evaporation a crystalline residue 
of benzoic acid. When 0‘0002 grm. of aconitine is gently warmed with 
4 drops of sulphuric acid, an odour of benzoic acid is evolved; and if, after 
five minutes, a few crystals of resorcin are added and the heat continued, 
a reddish-yellow colour, changing to intense red, is produced. No 
appreciable ash. 
§ 435. Tests for Aconitine. —The most satisfactory and the most 
delicate is the physiological test; the minutest trace of an aconite-holding 
liquid, applied to the tongue or lips, causes a peculiar numbing, tingling 
sensation which, once felt, can readily be remembered. 
An alkaloidal substance which, heated in a tube, melts approximately 
near the melting-point of aconitine, and gives off an acid vapour, would 
render one suspicious of aconitine, for most alkaloids give off alkaline 
