37 o poisons : their effects and detection. [§ 437. 
The solution in water is alkaline to litmus. The base is readily 
soluble in alcohol, in chloroform, and in ether. The alcoholic solution 
is dextro-rotatory. The solutions are bitter, but do not give the tingling 
sensation characteristic of aconitine. The hydrochloride, the hydro¬ 
bromide, the hydriodide, and the nitrate have been obtained in a 
crystalline state. The most characteristic salt is, however, the aurochlor 
derivative. When aqueous solutions of benzoyl-aconine chloride and 
auric chloride are mixed, a yellow precipitate is thrown down, which 
(dissolved in alcohol, after being dried over calcium chloride, and slowly 
evaporated in a desiccator) deposits colourless crystals entirely different 
from the yellow crystals of aconitine gold chloride. These crystals have 
the composition C 32 H 44 (AuCl 2 )NO n , and therefore, by theory, should 
yield 22-2 per cent, of gold, and 8 per cent, of chlorine. Professor 
Dunstan 1 found, as a mean of two determinations, 21-6 per cent, of 
gold, and 7-8 per cent, of chlorine. 
By hydrolysis, benzoyl-aconine yields benzoic acid, which can be 
shaken out of an acid solution by ether and identified ; one molecule of 
benzoic acid is formed from one molecule of benzoyl-aconine. 19-7 per 
cent, of benzoic acid should, according to the formula, be obtained ; 
Professor Dunstan found 18-85 per cent. 
Benzoic acid in the subliming cell begins to give a cloud at about 
77°-80°, and at or near 100° sublimes most rapidly. 
Benzoic acid, recovered from an acid solution by shaking out with 
ether, may be recognised as follows :—To the film left on evaporating 
off the ether add a drop of H 2 S0 4 and a few crystals of sodic nitrate, 
and heat gently for a short time ; pour the clear liquid into ammonia 
water, and add a drop of ammonium sulphide. A red-brown colour 
indicates benzoic' acid. The rationale of the test is as follows :—Dinitro- 
benzoic acid is first formed, and next, by the action of ammonium 
sulphide, this is converted into the red-brown ammonium diamidoben- 
zoate.—E. Mohler, Bull. Soc. Chem. (3), iii. 414-416. 
§ 437. The Lethal Dose of Aconitines. —Commercial aconitine has 
in the past varied in appearance from that of a gummy amorphous 
mass up to a purer kind in white crystals. 
Professor Dunstan 2 examined in 1893 fourteen samples, some of 
them of considerable age, and only found two samples (one of English, 
another of German make) which approached in melting-point and 
crystalline appearance pure aconitine ; the one, the English, melted at 
186°-187°, and contained about 3 per cent, of benzoyl-aconine ; the 
other, a German specimen, was almost pure ; the melting-point was 
187-5 J . At the present time, however, fairly pure crystalline aconitine 
may be obtained and assayed accurately by determining the proportion 
of acetic and benzoic acids. The physiological action of commercial 
1 Journ. Chem. Soc., T., 1893. 2 Op. cit., p. 491. 
