﻿H. Carmichael — Determination of Arsenic. 131 



(b.) A human stomach sent for analysis was, after the usual 

 physical examination, quartered. The part taken in the search 

 for inorganic poisons was cut into small pieces and the organic 

 matter destroyed with HC1 and KC10 3 as usual. Through the 

 filtered solution, which had been partially evaporated, S0 2 was 

 passed and the excess removed. H 2 S was passed through the 

 warm solution for twelve hours. The precipitate was thrown 

 on a small filter, and after thorough washing was drenched 

 with NH 4 HO. The nitrate was evaporated in small capsule, 

 twice moistened with concentrated HNO at a steam heat, then 

 moistened with fuming sulphuric acid and heated over direct 

 flame until the unoxidized sulphur had run into a single glob- 

 ule and the organic matter had been charred. A little warm 

 water was added, a few bubbles of S0 2 passed through the 

 solution, and the excess removed. Concentrated HC1 was 

 added and normal squares successively coated. The total 

 amount of arsenic in the stomach was computed to have been 

 2-76 mgrm . 



For verification one square was cut into narrow strips and 

 pushed into a hard glass tube of the size of a quill. One end 

 of the tube had previously been drawn down to a diameter of 

 one mm. and the opposite end, after the introduction of the 

 copper, was sealed with a mouth blowpipe. The bottle-shaped 

 tube thus formed was placed in an air-bath for the expulsion 

 of moisture and the bulb then raised to redness over a small 

 flame. A white cloud formed and condensed in the neck. 

 The sublimate was easily vaporized and driven from point to 

 point. Under the microscope the coating appeared as an aggre- 

 gation of sharply defined, highly refracting, regular octahe- 

 drons. The tube was sealed for future reference. The neck 

 of a second tube, prepared in the same manner, was broken off 

 and the arsenious oxide converted into the sulphide in a cur- 

 rent of H 2 S. The total exhibit then consisted of: 



(1.) A steel gray film on copper which did not rub bright. 



(2.) Highly refractive, regular octahedrons produced by the 

 oxidation of said film and by sublimation, and which, were 

 easily vaporized, reforming as octahedrons. 



(3.) A bright yellow substance formed by the action of H 2 S 

 upon the octahedral sublimate. 



Confirmatory tests might easily have been applied, but the 

 writer, having taken the customary precautions in testing purity 

 of chemicals and utensils, considered the proof of arsenic pre- 

 existing in the material submitted for examination as abun- 

 dant, and is of the opinion that such proof would, in similar 

 cases, be only weakened and obscured by the employment of 

 Marsh's or other familiar tests. 



Am. Jour. Sci— Third Series, Vol. XXXII, No. 188.— August, 1885. 

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