324 POISONS : THEIR EFFECTS AND DETECTION. [§ 39 I. 
water, and filtered. Tfie filtrate is shaken up in a separating funnel with 
much benzol,the benzol collected and distilled off; this extracts meconine. 
The watery fluid, free from meconine, is boiled with excess of magnesium 
carbonate, filtered hot, and the meconic acid set free by careful acidifica¬ 
tion by hydrochloric acid. Considering that the content of meconic 
acid in opium is often as low as 1-5 per cent., the identification of meconic 
acid must in many cases be micro-chemical, for JL. gramme of solid opium 
may only yield 1*5 mgrm. of meconic acid. The copper, silver, ferrous, 
and pyridine salts of meconic acid are fairly characteristic. The copper 
salt forms pale yellow needles and rods, brightly shining between crossed 
nicols. The silver salt gives yellow to black needles in clusters, with 
extinction parallel to the long axis. In polarised light the smaller cry¬ 
stals show a black cross. The pale red solution obtained by warming a 
minute quantity of dehydrated ferrous sulphate to a drop of meconic 
acid gives after a time reddish-brown crystals strongly pleochroic. 
The pyridine salt forms long, fine, colourless, single prismatic needles, 
sometimes grouped in sheaves, colour under crossed nicols pale grey. 
If the quantity is so small that it cannot be conveniently weighed, 
it may be estimated colorimetrically, by having a standard solution 
of meconic acid, containing 1 mgrm. in every c.c. A few drops 
of neutral ferric chloride are added in a Nessler cylinder to the liquid 
under examination ; and the tint thus obtained is imitated in the usual 
way, in another cylinder, by means of ferric chloride, the standard solu¬ 
tion, and water. It is also obvious that the weight of the meconic acid 
may be increased by converting it into the barium salt—100 parts of 
anhydrous baric meconate (Ba 2 C 7 H 2 0 7 ) being equivalent to 42*3 of 
meconic acid (C 7 H 4 0 7 ). 
IV.—The Strychnine or Tetanus-producing 1 Group of 
Alkaloids. 
1 . NUX VOMICA GROUP—STRYCHNINE—BRUCINE—IGASUR1NE. 
§ 391. Nux vomica is found in commerce both in the entire state and 
as a powder. It is the seed of the Strychnos nux vomica, or Koochla 
tree. The seed is about the size of a shilling, round, flattened, concavo- 
convex, of a yellowish-grey or light brown colour, covered with a velvety 
down of fine, radiating, silky hairs, which are coloured by a solution of 
iodine beautiful gold-yellow; the texture is tough and leathery, and the 
seeds are not easily pulverised; the taste is intensely bitter. The powder 
is not unlike that of liquorice, and, if met with in the pure state, gives a 
dark orange-red colour with nitric acid, which is destroyed by chloride of 
1 To this group also belong some of the opium alkaloids. See “ Thebaine,” 
“ Laudanine,” “ Codeine,” “ Hydrocotarnino.” 
