449 
SENSIBILITY OF THE PRINCIPAL REAGENTS ON 
STRYCHNINE. 
By Dr. J. E. De Vrij and E. A. Van Der Burg. 
Chromate of potash , or ferridcyanide of potassium and concen- 
trated sulphuric acid . — By these reagents ^ob^ou of a grain of 
strychnine can be detected, if one drop of a solution, con- 
taining 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 intro- 
ducing in this solution a very small fragment of a crystal of 
bichromate of potash or ferridcyanide of potassium, and 
moving this fragment with a glass rod in the solution, a 
beautiful dark purple colour 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, joboo °f a grain 
of strychnine can be detected. These reagents, like the fol- 
lowing, possess only the ascertained sensibility, provided the 
drop of liquid is contained in a capillary test-tube, in which 
the liquid, although only a drop, forms a small column, in 
which the formation of a precipitate can be observed by com- 
parison with a similar capillary tube filled with pure water, 
and mixed wdth the reagent. 
Tannic acid reveals arioo °f a grain of s try chine. 
Solution of chlorine in water , -30 Vo* 
Sulphocyanide of potassium, -3 ^0 o'* 
Neutral chromate of potash, -joVo* 
The precipitate formed by bin-iodide of potassium is 
brownish-red, and if dissolved in weak warm spirit, acidulated 
by sulphuric acid, beautiful crystals are formed of sulphate 
of iodo-strychnine, which polarize the light, as has been dis- 
covered by Mr. Herapath. The precipitate formed by iodide 
of mercury and potassium, by tannic acid, and by solution of 
chlorine in water, are white. This last reagent must be used 
in relatively large quantity, and the precipitate formed by it 
does not appear immediately. 
The precipitates formed by sulphocyanide of potassium 
and neutral chromate of potash are both crystalline. The 
colour of the former is white, and the form of the crystals 
observed by the microscope is very characteristic. The 
colour of the latter is a beautiful yellow. The formation of 
xxx. 60 
