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Volume 38, 1905
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The Composition of the Double Sulphocyanides.

(a.) Zinc.

Ten c.c. of the solution of the alkaloid were precipitated in the usual manner with sulphocyanide in the presence of a known excess of zinc-sulphate. The liquid was filtered, and the zinc in the filtrate was estimated by precipitation with sodium-carbonate. From this the amount of zinc which combines with a known amount of alkaloid could be found by difference. The following are the results:—

(1.) Quinine-ammonium-zinc-sulphocyanide : 10 c.c. N/10 quinine required 0·0424 gram zinc. Calculated for 3B, 2Zn (CNS)2—0·0424 gram zinc.

(2.) Cinchonine-ammonium-zinc-sulphocyanide: 10 c.c.N/10 cinchonine required 0·0486 gram zinc. Calculated for 4B, 3Zn (CAS)2—0·0487 gram zinc.

(3.) Cinchonine-potassium-zinc-sulphocyanide: 10 c.c.N/10 cinchonine required (a) 0·0472 gram zinc, (b) 0·0494 gram zinc. Calculated for 4B, 3Zn (CNS)2—0·0487 gram zinc.

(4.) Cocaine-ammonium-zinc-sulphocyanide: 20 c.c.N/10 cocaine required (a) 0·0210 gram zinc, (b) 0·0232 gram zinc. Calculated for 3B, Zn (CNS)2—0·0217 gram zinc.

(b.) Ammonia.

Precipitation was caused by a definite volume of normal ammonium-sulphocyanide in the presence of excess of zinc-sulphate. After washing the precipitate with a small quantity of a dilute solution of zinc-sulphate, the ammonia in the filtrate was estimated by distillation with caustic soda. It was thus possible to determine the amount of ammonia in the double salt.

The method of operation will be illustrated by means of the detailed analytical results obtained in the case of quinine.

Preliminary Test Experiment.—10 c.c. N ammonium-sulphocyanide on distillation with caustic soda gave ammonia =10 0 c.c.N acid. The filtrate from 10 c.c.N/10 quinine and 10 c.c. N ammonium-sulphocyanide gave ammonia = (i) 9·5 c.c. N acid, (ii) 9·5 c.c. N acid. ∴ 1 c.c. N quinine combines with 0·5 c.c. N ammonia.

(c.) Sulphocyanide.

The method has already been described and explained.

The following is a summary of the results obtained in the determination of ammonia and sulphocyanide:—

(1.) Quinine-ammonium-zinc-sulphocyanide: 10 c.c. N/10 quinine required (a) 0·5 c.c. N ammonia and 3·5 c.c.* sulpho-

[Footnote] * The mean of a large number of closely concordant determinations.

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cyanide, (b) 0·5 c.c. N ammonia. Calculated for 6B, 4Zn (CNS)2, 3 NH4CNS, 10 HCNS, 0·5—3·5 c.c. sulphocyanide.

(2.) Cinchonine-ammonium-zinc-sulphocyanide: 10 c.c.N/10 cinchonine required (a) 0·5 c.c. N ammonia and 3·0 c.c.* sulphocyanide, (b) 0·55 c.c. N ammonia. Calculated for 4B, 3Zn (CNS)2, 2 NH4CNS, 4 HCNS, 0·5—3·0 c.c. N sulphocyanide.

(3.) Cocaine-ammonium-zinc-sulphocyanide: 20 c.c. N/20 cocaine required (a) 0·5 c.c. N ammonia and 2·5 c.c. * N sulphocyanide, (b) 0·55 c.c. N ammonia. Calculated for 6B, 2Zn (CNS)2. 3 NH4CNS, 8 HCNS, 0·5—2·5 c.c. N sulphocyanide.

(d.) Alkaloid.

The precipitate from a known amount of alkaloid was collected on a Gooch crucible, and dried in a vacuum over sulphuric acid. Under these conditions the double salts still persistently retain a trace of water, which was removed by heating to 100°. The weights thus obtained should confirm those calculated from the formulæ, which were derived from the analytical results already given above.

(1.) Quinine-ammonium-zinc-sulphocyanide: Quinine = (a) 54·6 per cent., (b) 55·0 per cent. Calculated for 6B, 4Zn (CNS)2, 3NH4CNS, 10 HCNS—55·6 per cent.

(2.) Cinchonine-ammonium-zinc-sulphocyanide: Cinchonine = 54·9 per cent. Calculated for 4B, 3Zn (CNS)2, 2NH4CNS, 4 HCNS—55·7 per cent.

(3.) Cinchonine-potassium-zinc-sulphocyanide: Cinchonine = 55·4 per cent. Calculated for 4B, 3Zn (CNS2), 2 KCNS, 4 HCNS—55·6 per cent.

(4.) Cocaine-ammonium-zinc-sulphocyanide: This compound could not be dried without decomposition.

[Footnote] * The mean of a large number of closely concordant determinations.