256 ANNUAL OP SCIENTIFIC DISCOVERY. 



It is known that Messrs. Flandin and Danger have proposed to modify the 

 method of Marsh by applying sulphuric acid to carbonize the organic mat- 

 ters suspected of containing arsenic. M. Blondlot, while examining the 

 stomachs of three persons who had been poisoned by arsenious acid, found 

 on the mucous membrane small fragments of this acid, which superficially 

 were of a fine yellow color. He thought that this yellow matter resulted from 

 the formation of a sulphide of arsenic, resulting from the action of hydro- 

 sulphuric acid on the ai'senious acid, and ulterior experiments proved the 

 correctness of this view. As hydrosulphuric acid is formed in putrefied 

 organic matters, if they contain arsenic, the sulphide of arsenic will be 

 formed; and M. Blondlot shows that employing sulphuric acid to carbonize 

 these matters, will leave with the carbonized parts the sulphide of arsenic, 

 so that a portion of the poison will be lost. A committee of the Academy 

 has ascertained the exactitude of the assertions of M. Blondlot; and to avoid 

 this source of error, they propose to throw upon the carbonized remnant a 

 great deal of concentrated and boiling nitric acid, so as to transform the sul- 

 phide of arsenic into arsenious acid. By distilled water the excess of nitric 

 acid is then expelled, and the arsenic may be easily found by the method of 

 Marsh. 



SENSIBILITY OF THE PRINCIPAL REAGENTS ON STRYCHNINE. 



Professors De Vry and Der Burg, of Eotterdam, have recently published 

 the result of a series of experiments, showing the sensibility of the principal 

 reagents used for the detection of strychnine, when administered as a 

 poison. Their conclusions are as follows : 



Chromate of Potash, or Ferricyanide of Potassium and Concentrated Sulphuric 

 Acid. By these reagents ^iy^-o- of a grain of strychnine can be detected, if 

 one drop of a solution, containing one grain of strychnine in 60,000 grains 

 of water, is evaporated in a small porcelain dish on a water-bath, and the 

 remaining substance moistened with the smallest possible quantity of pure 

 concentrated sulphuric acid. By introducing in this solution a very small 

 fragment of a crystal of bicromate of potash or ferricyanide of potassium, 

 and moving this fragment with a glass rod in the solution, a beautiful dark 

 purple color is produced on every part of the surface of the porcelain that 

 has been in contact with the acid solution, and the fragment of one of the 

 two salts. 



Bin-iodide of Potassium, and Iodide of Mercury and Potassium : By a solution 

 of one of these compounds, 1 of a grain of strychnine can be detected. 

 These reagents, like the following, possess only the ascertained sensibility, 

 provided the drop of liquor is contained in a capillary test-tube, in which 

 the liquid, although only a drop, forms a small column, in which the forma- 

 tion of a precipitate can be observed by comparison with a similar capillary 

 tube filled with pure water, and mixed with the reagent. 



Tannic acid reveals -^^-QJJ of a grain of strychnine. 

 Solution of chlorine in water, -jj-^g-g-. 

 Sulphocyanide of potassium, _JL._. 

 Neutral chromate of potash, -g-T/n-Tp 



The precipitate formed by bin-iodide of potassium is brownish-red, and if 

 dissolved in weak, warm spirit, acidulated by sulphuric acid, beautiful crys- 



