REVIEWS DETECTION OF POISONS. 135 



been verified in his own laboratory ; and implicit confidence may be 

 placed in his statements, as they are not mere compilations or extracts, 

 but the results of actual experience. The subject of arsenic occupies 

 the larger portion of the book, being a more generally used poison, 

 and the methods of elimination applying equally well to many other 

 mineral substances. The processes are described in clear and intelli- 

 gible language, the best and most characteristic tests put prominently 

 forward, and the confirmatory experiments placed by themselves, there- 

 by obviating the difficulty which students often feel in choosing from a 

 large number of tests those which are most reliable. We cannot but 

 think, however, that the iodate of potash test, for distinguishing 

 arsenical from antimonial spots, is worthy of being placed among the 

 most characteristic reactions. 



Dr. Elderhorst has made some valuable additions, especially the 

 chapter on Oxalic Acid, all mention of which had been omitted from 

 the original work, through some unaccountable oversight ; for although 

 poisoning by oxalic acid is not now so frequent as formerly, yet cases 

 do sometimes occur, arising generally from accident or carelessness. 



In the chapter on Hydrocyanic Acid, the translator has inserted 

 some very important and useful additions ; but we think that mention 

 should have been made of Taylor's experiments on the detection of 

 prussic acid mixed with animal matter, even when in an advanced stage 

 of putrifaction. The test employed was that of Liebig, and gave emi- 

 nently successful results, and should therefore be tried in cases where 

 the body has been buried some time, although there is undoubtedly 

 but little chance of any appreciable trace of the acid remaining unvo- 

 latilized. In such cases, or where only the contents of the stomach 

 have to be examined, this process is preferable to that of distillation. 

 (See Chemical Gazette, 184/.) 



Dr. Elderhorst adds to this chapter a description of the ordinary 

 process for determining the quantity of prussic acid contained in any 

 liquid, consisting of the precipitation of the acid by means of nitrate 

 of silver, and calculation from the amount of cyanide obtained. This 

 process is open to the objection that it requires careful manipulation, 

 occupies a considerable time, and when hydrochloric acid is present, 

 becomes very complicated. It is curious that Dr. Elderhorst did not 

 mention the beautiful method of estimating prussic acid, proposed by 

 Liebig. As this plan is so easy of execution, occupying only a few 

 minutes, and as it may often be of great value to medical men who 

 are sometimes in uncertainty respecting the strength of their prussic 

 acid, we need scarcely oifer an apology for introducing a description. 



