246 Medico- Legal Application of Rienctts Test for Arsenic. 



number for 1829 of the American Journal of the Medical Sci- 

 ences, there is an exceedingly important paper by Samuel Jack- 

 son, late of Northumberland County, Pa., on a case of suspected 

 poisoning, which shows how necessary it is to know what sub- 

 stances are present in the fluid submitted for examination, before 

 forming an opinion. Four highly intelligent physicians, appoint- 

 ed a committee by the coroner for the examination of the con- 

 tents of the stomach, &c of a person recently deceased, drew up 



t 



a report to the effect — that he had died from the effects of arse- 

 nic, when none of that drug existed in the matters analyzed. 

 This serious error arose from the presence of tartar emetic and 

 common salt, combined with the color of the fluids. The tests 

 used were sulphuretted hydrogen, ammonia-sulphate of copper, 

 ammonia-nitrate of silver, and the production of the arsenical 

 alloy with copper. The action of all these reagents on the sus- 

 pected mixtures, was examined by the side of their effects on a 

 solution of arsenious acid, without detecting the error. But not- 

 withstanding this, and a certain amount of moral evidence pro- 

 duced against the accused, it has been made clear by Dr. Jack- 

 son that none of the poison was present. 



Of all the substances which may be met with in the matters 



examined, the salts of antimony give rise to the most serious diffi- 



culties. If sulphuretted hydrogen or Marsh's test be used, it is 

 impossible to distinguish between arsenic and antimony, when 

 both are present in certain proportions. It is therefore of the 

 first importance, that this and other similar sources of error should 

 be removed, so as to present to the jury a satisfactory report. 



The metallic substances to be expected, whether in broths, 

 medicines, or the contents of the stomach, &c. are the sulphates 

 of copper and zinc, acetate of lead, nitrate of bismuth, corrosive 

 sublimate, calomel, tartar emetic, and nitrate of silver. Of these 

 the salts of silver and lead are precipitated by the addition of suffi- 

 cient hydrochloric acid, and therefore do not interfere with the 

 test. The sulphate, and other compounds of copper and zinc, 

 do not exert any action in this case. But bismuth, mercury, and 

 antimony, attack the copper strips as well as arsenic. 



Bismuth.— Upon the addition of hydrochloric acid to the ni- 

 trate, a sub-nitrate is precipitated, but afterwards dissolved by the 

 acid. From this solution is produced, almost immediately, a 

 pinkish gray deposit of a crystalline texture, when clean copper 

 is introduced. The reduced bismuth accumulates on the strips 



