Page:Popular Science Monthly Volume 30.djvu/874

850 first volume was noticed in the "Monthly" for November, 1885. The second volume, which is now at hand, is devoted to fixed oils and fats, hydrocarbons, phenols, etc. Somewhat more than half of the volume is occupied by the first of these divisions. The physical characters of the oils are described first, and then the reactions based on the chemical properties. These sections are succeeded by a tabular classification of the oils based on a joint consideration of their origin, physical characters, and chemical constitution. Then follow methods of examining fatty oils and waxes for foreign matters and of identifying them, and after that come special methods of assaying some thirty of the principal commercial fixed oils. The next section, on the examination of lubricating oils, and that on mineral lubricating oils, which comes later, contain much matter of interest to the mechanical engineer as well as to the chemist. Appended to this division are descriptions of the chief saponification products of fixed oils—the higher fatty acids, soaps, glycerin, etc. The author has given much personal attention to methods of determining the density of fixed oils, for this property, being largely dependent on the constitution of the oils, is a more or less important means of identification. He especially recommends the Archimedean or plummet method of taking specific gravities, using Westphal's hydrostatic balance. In discriminating between butter and its imitations, he has found the specific gravity test valuable. He also recommends for examining butters the determination of the volatile fatty acids by Reichert's distillation process.

The temperature at which a mixture of the melted fat with glacial acetic acid becomes turbid on cooling is deemed by him another important indication, but he says that further experience is necessary before the trustworthiness of this test can be considered fully established.

The accurate determination of glycerin in a complex mixture is a problem which the author does not consider has received a satisfactory solution under all circumstances. After giving several methods of isolating glycerin in an approximately pure state, available in various circumstances, he proceeds to describe certain processes based on the chemical reactions of glycerin. A method originally suggested by J. A Wanklyn, has been very fully investigated in the author's laboratory, and proved to give very accurate results under certain conditions. This method is based on the oxidation of the glycerin by treatment with permanganate in presence of excess of caustic alkali, whereby it is converted into oxalic acid, carbon dioxide, and water. The excess of permanganate is then destroyed by a sulphite, the filtrate acidulated with acetic acid, and the oxalate determined as a calcium salt. In the presence of foreign bodies yielding oxalic acid on oxidation, the process is evidently useless.

In the second division, after some general description of the hydrocarbons, the tars of various origins are considered, and then the bitumens. The important commercial products derived from petroleum and shale are duly described, after which are taken up the terpenes, benzene and its homologues, naphthalene and anthracene. The properties and methods of assay of monohydric and dihydric phenols are given in the concluding division. The chapters on the aromatic acids and tannins have been deferred to the third volume, which will contain also chapters on coloring-matters, cyanogen compounds, organic bases, albuminoids, etc.

Agassiz Association is an organization for the practical study of Nature, which originated some ten years ago, under an impulse given by the editor of "The Swiss Cross," in the Lenox High-School, Massachusetts. Other societies joined the original society to co-operate with it; and these affiliated local societies or "chapters" have increased till they number nine hundred and eighty-four, having from four to one hundred and twenty members each, of all ages from four years to eighty-four years, distributed in nearly all the States and Territories, and in Canada, England, Ireland, Scotland, Chili, Japan, and Persia. The