1905] BRIEFER ARTICLES 309 
An attempt was made to remove the free iodin from the hot colorless 
starch-iodin solution by the addition of chloroform, but it was’ found 
difficult to handle the material, as chloroform boils at about 60° C. Sub- 
sequent experiments, however, showed that unaltered potato starch grains 
as well as a solution of potato starch would remove the iodin from a chloro- 
formic solution at the ordinary temperature. These experiments were 
conducted as follows: 5°¢ of an iodin solution, of the strength already 
stated, were shaken in a separatory funnel with 25°¢ of chloroform, and 
most of the chloroform containing the iodin separated. To this was 
added 58™ of dried starch. The latter, however, did not take up the 
iodin from the solution; but on the addition of a small quantity of water 
(about ro°°) and after shaking the mixture, the starch and iodin combined, 
and almost all of the iodin in the chloroformic solution may be removed 
in this way. The addition of 2°¢ of potassium iodid solution (5 per cent.), 
even with 0.5®™ of starch, causes the iodin to be taken up immediately. 
The starch in a soluble starch solution also combines immediately with 
the iodin in a chloroformic solution. 
In summing up the observations on the behavior of iodin and starch, 
it seems to me that we are dealing with a chemical compound of iodin and 
soluble starch; but that the combination is a feeble one, being easily 
dissociated upon the application of heat, and the iodin being more or less 
volatilized. Also the facility with which soluble starch takes up the iodin 
in @ chloroformic solution indicates that the affinity of starch for iodin is 
considerably greater than heretofore supposed. . 
STAINING OF THE GRAIN, 
While T have obtained at times some beautiful results by the use of 
anilin stains, it has been impossible for me until now to duplicate some of 
my earlier results. I have ‘succeeded, however, in developing a method 
. the staining of wheat starch which yields uniformly satisfactory results. 
38 as follows: to o. 5008™ of wheat starch add 2° of an aqueous iodin 
rena (containing 0.1 per cent. of iodin and o.5 per cent. of potassium 
); mix well and allow the mixture to stand from 20 to 30:minutes in a 
Porcelain dish or watch crystal; then add 2°¢ of a saturated aqueous solu- 
ne a et (18™ of gentian violet to roo° of water) ; allow this 
mou : from 12 to 24 hours; examining the grains from time to time by 
: ning them in water. When the grains are satisfactorily stained, the 
muxture is transferred to a filter and the excess of stain is removed as 
= “S Possible by washing the magma with water. The material is 
allowed to dry spontaneously or between pieces of bibulous paper. 
