Dr. Christison's Treatise on Poisons. 281 



Mercury. — Dr. Christison introduces his remarks on the detec- 

 tion of corrosive sublimate in mixed fluids, by referring to the ex- 

 periments of Berthollet, Orfila, Boullay, and Taddei, on the de- 

 composition of this poison by many organic substances. It is now 

 ascertained that various vegetable solutions convert corrosive subli- 

 mate into calomel, some producing the change rapidly, and others 

 after an interval of hours or even days. Strong tea immediately 

 becomes turbid from this cause, when mixed with a few grains of 

 the poison, while infusion of galls acts only after the space of some 

 hours. Many animal principles produce the same change, some 

 acting instantaneously, and others slowly. Of the soluble animal 

 substances, albumen, curd, osmazome, and gelatine, possess this 

 property in an eminent degree, especially the former, which is 

 hence employed as an antidote to the effects of corrosive sublimate. 

 Fibrin, coagulated albumen, membranous surfaces, and generally, 

 the soft solids both in the dead and living animal, produce a similar 

 effect ; and, in fact, the corrosive power of this poison depends on 

 the chemical action here alluded to. Owing to this cause, death 

 may be occasioned by corrosive sublimate, and yet none of the 

 poison be found either in the stomach or in the substances ejected 

 from it. The chemist has therefore to search for decomposed as 

 well as undecomposed poison, the former existing in the state of 

 calomel in combination with organic matter. 



We have premised these particulars in explanation of the pro- 

 cess recommended by Dr. Christison in cases of poisoning by cor- 

 rosive sublimate, in all of which cases the poison is necessarily 

 more or less subject to the decomposing agency of organic sub- 

 stances. Dr. C. remarks that he " has experienced considerable 

 difficulty in fixing on a satisfactory process for detecting corrosive 

 sublimate, when it exists in mixtures of the kind now described, 

 and in such minute proportions as the medical jurist will generally 

 have to search for. I have satisfied myself that none of the me- 

 thods in common use are sufficient in these circumstances ; — even 

 the otherwise well designed processes of Professor Orfila being in 

 some essential respects defective. On the whole, the following 

 plan has appeared to me the most simple and the most generally 

 applicable. It is a double process, of which sometimes the first 

 part, sometimes the second, sometimes both, may be required. The 

 first removes the corrosive sublimate undecomposed from the mix- 

 ture, which may be accomplished when its proportion is not minute; 

 the second, when the proportion of corrosive sublimate is too small 

 to admit of being so removed, separates from the mixture metallic 

 mercury; and the analyst will know which of the two to employ by 

 using protochloride of tin as a trial test in the following manner." 



" A fluid mixture being in the first instance made, if necessary, 

 by dividing all soft solids into small fragments, and boiling the mass 

 in distilled water, a small portion is to be filtered for the trial. If 

 protochloride of tin causes a pretty deep ash-gray or grayish-black 

 colour, the first process will probably be successful ; if the shade 



N. S. Vol. 8. No. 46. Oct. 1830. 2 O required 



