Means of detecting Arsenic in the Animal Body, Sfc. 285 



phuret of antimony is formed. Another process will be stated 

 for arriving at the same end, when mention is made of a method 

 by which I propose to separate arsenic from organic substances. 

 The importance of studying this double tache will be evident to 

 every reflecting mind, for it may not unfrequently happen that the 

 physician called upon to administer to a person supposed to be 

 laboring under the effects of arsenic, may use tartar emetic to dis- 

 embarrass the stomach of the supposed poison ; death taking 

 place, an examination is made of the liquid found in the stomach 

 and intestines, of urine, &c., by means of Marsh's apparatus, and 

 a tache is obtained which is not easily volatilized, and which has 

 the appearance of antimony. What then is to be done ? Why, 

 we are to proceed in our experiments as just stated, and the two 

 metals, if both be present, are to be separated. 



The tache from sulphur has all the characteristics of that sub- 

 stance ; color yellow, volatile, with a suffocating smell, &c. 

 There is not the least probability of confounding it with any 

 thing else. 



The tache from phosphorus possesses three different shades, 

 brilliant white, brilliant yellow, and rust color. When the quan- 

 tity of phosphorus is very small, either the first, or only the first 

 and second are seen. It is volatile, reddens litmus paper, and 

 is insoluble in cold nitric acid, so that there cannot be the least 

 occasion for mistaking between this and arsenic. 



The next substance that produces a tache when introduced into 

 the apparatus in question, is iron, but it ought not to be classed 

 with the others, for I am firmly convinced that it is not due to 

 any iron that may be dissolved by the hydrogen ; in other words 

 that there is no ferruginous hydrogen. My reason for so be- 

 lieving is based upon the following facts : — If we desire to obtain 

 this tache, a considerable quantity of iron, or some salt of iron, 

 must be used, and the gas made to generate rapidly. Now observe 

 what must take place. The action of the liquid being violent, a 

 spray is formed, which consists of the dilute acid and whatever 

 salts it may hold in solution, in this case iron as one ; this spray 

 passes along with the hydrogen through the jet ; the hydrogen 

 being now ignited, a porcelain surface is placed in contact with 

 the flame, which, becoming heated, enables it to evaporate 

 the water from the salt of iron, which deposits itself, and after- 

 wards becomes decomposed by a continuation of the heat, the 



Vol. XL, No. 2.— Jan.-March, 1841. 37 



