MECONIC ACID. 
§ 39° •] 
323 
years this substance has been taken up into the nostrils as a narcotic snub. £ of 
a grain is stated to have been fatal; even ^ has produced serious symptoms. 
§ 390. Meconic Acid, (C 7 H 4 0 7 ), or 1 
CO 
HC COH 
HOOC-C 
C-COOH 
0 
crystallises in white shining scales or small rhombic prisms, with three molecules of 
water (C 7 H 4 0 7 -|-3H 2 0), but at 100° this is lost, and it becomes an opaque white mass, 
melting at 150° C. It reddens litmus, and has a sourish taste. It is soluble in 115 
parts of cold, but dissolves in 4 parts of boiling water ; it dissolves easily in alcohol, 
less so in ether. It forms well-marked salts ; the barium and calcium salts crystallise 
with one molecule of water, the former having the composition BaH 4 (C 7 H0 7 ) 2 ; the 
latter, if ammonium meconate is precipitated by calcium chloride, CaH 4 (C 7 H0 7 ) 2 ; 
but if calcium chloride is added to the acid itself, the salt has the composition 
C 7 H 2 Ca0 7 + H 2 0. If meconic acid is gently heated, it decomposes into carbon dioxide 
and comenic acid (C 6 H 4 0 5 ). If the heat is stronger, pyromeconic acid (C 5 H 4 0 3 ), carbon 
dioxide, water, acetic acid, and benzole are formed. Pyromeconic acid is readily 
sublimed in large transparent tables. Chloride of iron, and soluble iron salts generally, 
give with meconic acid (even in great dilution) a lively red colour, which is not altered 
by heat, nor by the addition of HC1, nor by that of gold chloride. Sugar of lead and 
nitrate of silver each give a white precipitate ; and mercurous and mercuric nitrates 
white and yellow precipitates. In any case where the analyst has found only meconic 
acid, the question may be raised in court as to whether it is a poison or not. The early 
experiments of Serturner , 2 Langer, Vogel, Sommering, and Grape 3 showed that, in 
comparatively speaking large doses, it had but little, if any, action on dogs or men. 
Albers 4 has, however, experimented on frogs, and found that in doses of T to 2 grm. 
there is, first, a narcotic action, and later, convulsions and death. According to 
Schroff , 5 there is a slight narcotic action on man. 
The most generally accepted view at the present time is that the 
physiological action of meconic acid is similar to that of lactic acid— 
viz. large doses cause some depression and feeble narcosis. 
In a special research amongst organic fluids for meconic acid, the 
.substances are extracted by alcohol feebly acidulated with nitric acid ; on 
filtration the alcohol, after the addition of a little water, is distilled off, 
and to the remaining fluid a solution of acetate of lead is added, and the 
whole filtered. The filtrate will contain any alkaloids, whilst meconic 
acid, if present, is bound up with the lead on the filter. The meconate 
of lead may be either washed or digested in strong acetic acid to purify 
it, suspended in watec, and freed from lead by SH 2 ; the filtrate from 
the lead sulphide may be tested by ferric chloride, or, preferably, at 
once evaporated to dryness, and weighed. An alternative method of 
separating meconic acid is extraction with alcohol acidified with hydro¬ 
chloric acid. The filtrate is evaporated to dryness, taken up with hot 
1 Mulliken, Identification of Organic Substances, vol. i., makes the statement that 
free meconic acid cannot be isolated. This is wrong. 
2 Ann. Phys., xxv. 56 ; xxvii. 183. 
3 De opio et de illis quibus constat partibus, Berol., 1822. 
4 Arch. Path. Anat., xxvi. 248. 5 Med. Jahresb., 1869. 
