416 
CHEMICAL REACTIONS OF STRYCHNIA. 
developing the tints with strychnia, bichromate of potash is 
assuredly the worst, for — 
“ 1st. It is itself coloured by the acid, and may thus com¬ 
plicate the result. 
“ 2d. It will not act when organic matter is present, as 
for example, the vegetable acids,—citric and tartaric, cream 
of tartar, tartar-emetic, potassio-tartrate of soda, the residue' 
of an effervescing draught, sugar, gum, and even a little 
morphia. 
“ 3d. It will not act when nitre, nitric acid, or common 
salt are present with the strychnia. 
“4th. It is of all the tests the least delicate: for while 
the peroxide of manganese, or the peroxide of lead, will dis¬ 
cover the presence of the 2 0 J-^jth of a grain of strychnia, the 
bichromate will not act well with less than the - 0 l 5 - 0 th of a 
grain. 
“It is true that by means of the process which I shall 
hereafter detail for extracting the alkaloid, none of those 
impurities will be present; yet, in making a comparison of 
the respective values of the several tests, it is right to know 
that the bichromate of potash reaction is the least satis¬ 
factory.” * 
The true cause of its want of delicacy is the rapidity with 
which it oxidizes the alkaloid; and therefore the peroxides 
of manganese and lead, because of their evolving oxygen 
slowly, are more delicate and suitable to the purpose, for 
their reactions take time to develop and the colour is far more 
enduring. Finding that the modus ojmrandi of the test was 
the action of nascent oxygen upon the strychnia, it occurred 
to me that the galvanic current might be used instead of the 
oxygen compound. 
“The mode of applying the galvanic test is as follows:— 
Place a drop of a solution of strychnia (say of one part of the 
alkaloid in 10,000, or even 20,000, of water) in a cup-shaped 
depression made in a piece of platinum foil. Allow the fluid 
to evaporate, and, when dry, moisten the spot with a drop 
of concentrated sulphuric acid. Connect the foil with the 
positive pole of a single cell of Grove’s or Smee’s battery, 
and then touch the acid with a platinum terminal of the 
negative pole. In an instant the violet colour will flash out, 
and, on removing the pole from the acid, the tint will 
remain.” f 
Bv this mode of proceeding the colour is perfectly under 
control, and the test is free from every known source of fal- 
* ‘Lancet,’ June 28, 185G, p. 708. 
f Ibid. 
