136 REVIEWS DETECTION OF POISONS. 



A tube (alkalimeter) capable of containing 1000 grains of water, is 

 graduated into 100 parts, and marked, beginning from >0 above; 17 

 grains of nitrate of silver are put in, and the tube filled up to with 

 distilled water, the mouth closed with the thumb, and the tube agita- 

 ted until solution has taken place, a few drops will adhere to the 

 thumb, but these can be scraped off. Gf the prussic acid to be ex- 

 amined, 54 grains are accurately weighed out, mixed with about an 

 ounce of water, and an excess of solution of caustic potash added. A 

 little common salt may also be added, but is not absolutely necessary. 

 The nitrate of silver solution is now pou^red in until permanent tur- 

 bidity is produced ; the precipitate first formed dissolves on stirring, 

 but when it is no longer taken up on continued agitation, the opera- 

 tion is finished. The number of divisions of the nitrate solution 

 employed, are now read off, and each one of the 100 represents 0, 1, 

 or one -tenth per cent, of anhydrous hydrocyanic acid. Suppose 28^ 

 measure have been employed, then the liquid contains 2.85 per cent, 

 of pure acid. 



Under the head of Strychnine, the various tests are described, and 

 the methods explained by which the alkaloid can be separated in the 

 state of purity required for their success. The suspected substance is 

 treated with alcohol and tartaric acid, the liquid evaporated, treated 

 with water, and the aqueous solution mixed with ammonia, which sets 

 the strychnine free ; by agitation with ether it can be extracted. Since 

 the publication of the above translation, chloroform has been recom- 

 mended as a substitute for ether. The chloroform rapidly absorbs the 

 strychnine, and settles to the bottom, it can be drawn off, mixed with 

 twice its volume of alcohol, and this solution yields on evaporation 

 very distinct and pure crystals of the alkaloid. This process seems to 

 be an excellent one, and likely to supersede all others. Some experi- 

 ments made in the writer's laboratory with one third of a grain of 

 strychnine dissolved in one quart of beer, were eminently successful, 

 and afforded sufficient pure substance to make several chromic acid 

 tests. 



We cannot too strongly recommend this excellent little work to the 

 attention of working chemists, medical men, and all interested in 

 chemico-legai investigations ; and many thanks are due to Dr. Elder- 

 horst, not only for his excellent translation, which contains very few 

 Germanisms, — herein differing most favorably from some other American 

 translations of chemical works, — but also for his own very valuable 

 additions. 



H C. 



