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solution formed by boiling one part of finely-divided starch in one hundred of 
water saturated with salt, and filtering the same, is imputrescible, and may 
be preserved for a long time. After a year the author’s solution appeared to 
be less sensitive to iodine, and after three or four years was no longer 
coloured by that reagent. It was neutral, limpid, contained no trace of any 
organized ferment, reduced the copper solution energetically, and was coloured 
brown by alkalies. Determined by the copper test, every 100 cc. contained 
0*111 gramme of dextrose ; but when ferrocyanide of potassium was em- 
ployed, which is not affected by dextrin, 100 cc. contained 0*102 gramme. 
A mixture of nine-tenths dextrose and one-tenth dextrin was consequently 
formed from the starch. The solution in a tube 200 mm. long rotated to the 
right : Da = + 0*15°. The author calls attention to the importance of the 
transformation of starch in the cold without a ferment in its bearing on the 
physiology of vegetable growth. — (Bull. Soc. Chim. xxxi. 10). 
The Action of Isomorphous Salts in Exciting the Crystallization of Super- 
saturated Solutions of each other. — Mr. J ohn M. Thomson, of King’s College, 
has read a paper on this subject before the Chemical Society ( Journ . Chem . 
Soc., May 1879). He points out that two explanations have been put 
forward to account for this action. One, that the crystallization is induced 
by the entrance of a particle of the same salt j and the other, that, a purely 
physical cause, such as the presence of greasy, fatty, or oily matter in thin 
films, may be found active in exciting the crystallization. A solution of 
potassium tri-iodide, which had remained under a desiccator for a consider- 
able time without change, was found after a short exposure to the air to be 
filled with crystals of the tri-iodide. The solution had undergone super- 
saturation, and its deliquescent nature would most likely prevent its floating 
in the air as a solid : it obviously was not a particle of the salt itself which 
excited the crystallization. In his experiments the supersaturated solution 
was placed in a flask, and that of an isomorphous salt to be employed as 
nucleus in a thin glass bulb, which was supported in the neck of the flask with 
a plug of cotton wool. The solution in the bulb-tube having been boiled, the 
tube was stoppered with cotton wool. The contents of the flask were again 
boiled, and the arrangement placed aside for eighteen or twenty hours. To 
perform an experiment the solution in the bulb-tube was crystallized by 
touching it with a platinum wire, and the bulb-tube lowered into the liquid 
of the flask, allowed to remain there some time to see that the introduction 
of the glass into the fluid did not cause crystallization, and finally lightly 
broken in the fluid. Only a few examples of activity can be mentioned 
here. The action of isomorphous sulphates on magnesium sulphate was very 
successful. Zinc and nickel sulphate were active at once ; cobalt and iron 
sulphate after some time ; nickel sulphate with 6H 2 0, iron sulphate with 
a:H 2 0, and cobalt sulphate with xTL 2 0 after some time. Sodium selenate 
with sodium sulphate crystallized immediately ; chromium and iron alums 
with common alum were active. Hydrodisodic arsenate with the corre- 
sponding phosphate crystallized immediately and very rapidly. The experi- 
ments with the sulphates of nickel, magnesium, and zinc confirm the results 
of Gernez, published in 1866. The general results arrived at by Mr. Thomson 
are : — (A) When the mixture consists of two salts which are not isomor- 
phous : (1) Sudden crystallization may take place, gradually spreading 
