530 Chronicles of Science. [Oct., 



residue, which he then keeps at 150°, until no loss of weight is 

 observed. This gives the total residue. He then gradually ignites 

 in a platinum crucible — allowing only a part to come to a red heat 

 — until the residue is white, then moistens with solution of carbonate 

 of ammonia, dries at 150°, and reweighs. The difference is very 

 nearly the weight of the organic matter. But as the carbonate of 

 magnesia will have undergone some alteration, to be exact, the 

 author determines the carbonic acid both in the first and second 

 residues, and adds the difference to the second weighing, thereby 

 reducing by so much the organic matter. Heintz states that this 

 method only gives accurate results when the magnesia is present in 

 an organic combination, and when the water is not strongly charged 

 with the oxides of iron and manganese, whose state of oxidation 

 may be altered by the ignitions. The presence of chloride of 

 magnesium is also a source of error, as all chemists will under- 

 stand. 



In technical chemistry one noteworthy fact is the process 

 invented by M. Paraf-Javal, for the Transformation of Liquid into 

 Solid Fats. It was known that under the influence of a strong 

 alkali oleic acid splits up into acetic and palmitic acids This fact 

 the inventor applies industrially as follows : — He heats one part of 

 oleic acid with two or three times its weight of hydrate of potash 

 almost to the fusing point of the potash. A large amount of 

 hydrogen is disengaged in the reaction that ensues, and a porous, 

 swollen mass results. The sudden collapse of this mass indicates 

 that the reaction has ended. Water is now added in small quanti- 

 ties, so as to obtain a strong alkaline solution in which the soap 

 formed is insoluble. The soap can thus be separated, and the 

 greater part of the alkali recovered. When separated the soap is 

 dissolved in water and afterwards precipitated by common salt. It 

 is then decomposed by treatment with an acid, and the palmitic 

 acid is purified by distillation. The liquid from which the soap is 

 separated will, of course, contain an acetate of the alkali. This can 

 be separated and the acetic acid obtained by means known to all 

 chemists. Soda, it is said, may be used in place of potash. It is 

 right to say that this process has been patented in France. 



A method of obtaining caustic baryta cheaply is a great deside- 

 ratum ; and we give one recently published by M. Tessie du Motay, 

 which, however, we fear is not likely to receive an extensive appli- 

 cation. The inventor takes carbonate of baryta, mixes it into a 

 paste with fat resin and charcoal, and burns the mixture in a rever- 

 beratory furnace. In this way the carbonate is reduced and the 

 baryta is left mixed with some charcoal. The latter is burned away 

 by passing a current of oxygen through the furnace, and the heat 

 developed in this operation is so great as to prevent the recom- 

 bination of the baryta with the carbonic acid produced. Baryta 



