206 KANSAS UNIVERSITY QUARTERLY. 
scope, and with the physiological test also, they can be depended 
upon to identify the alkaloid. Our experience has been that the 
most delicate tests could be made by the use of sulphuric acid and 
potassium bichromate. In this case the succession of colors, blue, 
purple and red is very characteristic. ‘The color with some other 
oxidizing agent, as manganese dioxide, is frequently of value as a 
confirmatory test, especially in the presence of other substances 
such as caffein. With this latter reagant the color reactions ap- 
pear more slowly, but are just as definite finally. 
In these experiments the delicacy of the color reaction with sul- 
phuric acid and potassium bichromate was first established. In 
order to do this, solutions of strychnine of various strengths were 
prepared by dissolving a known weight of the alkaloid in acetic 
acid and water. The strength of these solutions varied from one 
grain of strychnine dissolved in 1000 cc. of water to one part in 
1,000,000. One tenth of a cubic centimeter of the solution, corre- 
sponding to one-tenth the weight of strychnine in one cubic centi- 
meter, was evaporated to dryness on a porcelain crucible cover, 
over a water bath, taking care to have all the strychnine deposited 
at one point on the cover. This residue was then moistened with 
one drop of concentrated sulphuric acid and a minute particle of 
potassium dichromate was drawn through the droplet with a fine 
glass rod. This gave the characteristic color reaction. Beginning 
with a concentrated solution of strychnine, the tests were made in 
solutions of greater dilution till a point was reached at which it 
was not possible to detect the alkaloid by this test. The micro- 
scope was not used in the examination of the color test. 
In the second series of tests, after evaporating the solution to 
dryness on the porcelain cover, it was treated with a drop of con- 
centrated sulphuric acid, and heated for fifteen minutes on the water 
bath, then the test was made in the usual manner. 
In the third series of tests the conditions were such as would 
prevail in the ordinary course of analysis, when organic matter is 
present. To each portion, before testing, a measured quantity of 
extract of beef was added, twenty-five cc. of alcohol and a few 
drops of acetic acid and the whole was digested for an hour ona 
water bath. The mixture was then diluted, filtered, and evapo- 
rated to dryness on a water bath, allowed to cool and dissolved in 
water acidulated with a drop of acetic acid. The solution was 
made alkaline with potassium hydrate and shaken out twice with 
chloroform, about ten cc. of this solvent being used each time. 
The mixed chloroform solutions were then evaporated to dryness 
