In 1000 c.c.  In 200 c.c. 
Grammes.  Grains. 
Calcium chloride¹ 299.70 925.8
Magnesium " 56.93 175.7
Strontium " 1.47 4.5
Sodium " 20.16 62.2
Potassium " 5.13 15.8
------ ------
383.39 1184.0
¹Trace of bromide.

There is of course some variation in the bittern obtained from different brines, but it appears of interest to call attention to this correspondence in composition, as indicating that the liquid for filling such grenades is obtained by adding two volumes of water to one of the “bittern.”  The latter statement is fairly proved by the presence of the bromine, and certainly from an economical standpoint such should be its method of manufacture.—­Amer.  Chem.  Jour.

* * * * *

MOLECULAR WEIGHTS.

A new and most valuable method of determining the molecular weights of non-volatile as well as volatile substances has just been brought into prominence by Prof.  Victor Meyer (Berichte, 1888, No. 3).  The method itself was discovered by M. Raoult, and finally perfected by him in 1886, but up to the present has been but little utilized by chemists.  It will be remembered that Prof.  Meyer has recently discovered two isomeric series of derivatives of benzil, differing only in the position of the various groups in space.  If each couple of isomers possess the same molecular weight, a certain modification of the new Van’t Hoff-Wislicenus theory as to the position of atoms in space is rendered necessary; but if the two are polymers, one having a molecular weight n times that of the other, then the theory in its present form will still hold.  Hence it was imperative to determine without doubt the molecular weight of some two typical isomers.  But the compounds in question are not volatile, so that vapor density determinations were out of the question.  In this difficulty Prof.  Meyer has tested the discovery of M. Raoult upon a number of compounds of known molecular weights, and found it perfectly reliable and easy of application.  The method depends upon the lowering of the solidifying point of a solvent, such as water, benzine, or glacial acetic acid, by the introduction of a given weight of the substance whose molecular weight is to be determined.  The amount by which the solidifying point is lowered is connected with the molecular weight, M, by the following extremely simple formula:  M = T x (P / C); where C represents the amount by which the point of congelation is lowered, P the weight of anhydrous substance dissolved in 100 grammes of the solvent, and T a constant for the same solvent readily determined from volatile substances whose molecular weights are well known.  On applying this law to the case of two isomeric benzil derivatives, the molecular