the first or general part of the book, theory alone is considered, the ionic theory of electrolytic dissociation is clearly and concisely given, and the laws governing it are discussed. In the section following are described the various forms of apparatus for the measurement of current magnitudes and tension. The section on current sources is very complete, the best forms of primary and secondary elements being considered in detail, as well as numerous physical methods of producing the current. The section on accumulators is excellent, and the general rules for handling them precise. Numerous examples and tables of experiments are given, to illustrate the working of the apparatus described. The process of analysis under varying conditions is considered in full, and detailed descriptions of special forms of apparatus and the arrangements thereof are outlined. While the simpler arrangements are not slighted, more attention is given to a full description of the equipment of the Electrochemical Institute at Aachen, under the direction of the author. The second general division of the book is devoted to the quantitative determination of the metals, and herein lies the value of the work to the analyst. No criticism of the manner of detailing the various methods can be made, since all the weak as well as the strong points are carefully considered, and the directions are not involved. Full references to all the literature to date are given. Following this the work ends with an appendix of seventy pages containing schematic outlines of some applied examples of electrochemical analysis. Methods for the analysis of brass, bronzes, alloys of different compositions, iron ores, mattes, etc., are given. The work has two indexes, one of authors and one of subjects, and both are complete. The translators have done their work well, and throughout the work make frequent notations from their own experience. The illustrations are all of a high class. As a whole the work is commended either as a text-book or reference book. W. WALLEY DAVIS.

A MANUAL OF QUANTITATIVE CHEMICAL ANALYSIS. B.S. New York: John Wiley & Sons. vi + 82 pp. "This little manual is intended for the use

quantitative analysis.

BY E. F. LADD,
Price $1.00.

of beginners in

the methods given should be correct if not elaborate. An ex

amination of the work shows it to contain numerous errors, many of which would get the beginner into serious difficulties. Yet some of the methods were correctly described by the author ten years ago in the Geneva reports.

It is surprising that the reader for any responsible publishing house would recommend the publication of a work containing so many manifest errors. H. A. HUSTON.

ERRATA.

In Vol. 19, p. 886, line 9, "0.30" and "0.22" read "0.030" and "0.022," respectively; and on the same page, line 11, for "0.08" and "0.02" read "0.008" and "0.002", respectively. In Vol. 20, p. 115, line 34, for "10.2" read “ In Vol. 20, p. 135, line 13, for " In Vol. 20, p. 465, line 5 from bottom, for from the titration" read "private titration."

16.4" read "

BOOKS RECEIVED.

31.8".

10.4".

Potatoes. Bulletin No. 72. Strawberries. Bulletin No. 73. Kentucky Agricultural Experiment Station of the State College of Kentucky, Lexington, Kentucky, 1898.

Variety Tests of Fruits. Bulletin No. 52. Concentrated Feed-Stuffs. Bulletin No. 53. Hatch Experiment Station of the Massachusetts Agricultural College, Amherst, Mass. 1898.

Larkspur. Poisoning of Sheep. Bulletin No. 15. Montana Agricultural Experiment Station, Bozeman, Montana, July, 1897.

The Periodical Cicada in West Virginia. Bulletin No. 50. Commercial Fertilizers. Bulletin No. 51. West Virginia Agricultural Experiment Station, Morgantown, West Va., January, 1898.

Memorial of the National Pure Food and Drug Congress to the Congress of the United States. Copies of this pamphlet can be procured from the chairman, Wm. Frear, State College, Pa.

Sugar Beets. Summary of Investigation from 1888 to 1898. Report for 1897. Proposed Experiments for 1898. Bulletin No. 56. April, 1898. Chemical and Agricultural Divisions, Agricultural Experiment Station, Univ. of Minnesota, St. Anthony Park, Ramsey County, Minn.

Twenty-first Annual Report of the Connecticut Agricultural Experiment Station for 1897. Part IV. Experiments on Tobacco. Availability of Fertilizer. Nitrogen. Commercial Fertilizers for Forcing House Crops. Steam Sterilizer for Soils. Composition of Violet Plants and Flowers. Insect Notes. Analyses of Feeds, and of Milk and Butter. Legumin and other Proteids of Legumin. Proteids of Soy Bean. Feed

Tests. Connecticut Agricultural Experiment Station, New Haven, Conn. Red Rice. Bulletin No. 50. Second Series. Agricultural Experiment Station, Baton Rouge, La.

Tenth Annual Report of the Storrs Agricultural Experiment Station, First Part. A Report of the Executive Committee, Treasurer and Director; A Study of the Rations Fed to Milch Cows; Nitrogenous Feeding Stuffs and Formulas for Feeding. Storrs Agricultural Experiment Station, Storr, Tolland Co., Conn. 128 pp.

Insecticides, Their Preparation and Use. Bulletin No. 126, May, 1898, Connecticut Agricultural Experiment Station, New Haven, Coun.

12 PP.

The Cost of Plant Food in Connecticut, Spring months of 1898. Bulletin No. 127, May, 1898. Connecticut Agricultural Experiment Station, New Haven, Conn. 10 PP.

A Manual of Quantitative Chemical Analysis. By E. F. Ladd, B.S. New York: John Wiley & Sons. 1898. vi +82 pp. Price, $1.00.

Bulletin No. 32, Chemical Studies: (1) Drinking Waters; (2) Wool Scouring; (3) Soil Humus; (4) Analysis of Foods; (5) Vinegars. April, 1898. Fargo, N. D.: Government Agricultural Experiment Station for North Dakota.

16 pp.

Jahrbuch der organischen Chemie, unter mitwirkung von B. Rassow, Leipzig; C. Schwalbe, Leipzig; H. Stobbe, Leipzig; J. Troeger, Braunschweig; Herausgegeben von Gaetano Minunni, Palermo. Dritter Jahrgang, 1895. Leipzig: Johann Ambrosius Barth. 1898. x+1162 pp.

Price, M. 30.

A Preliminary Report upon the Bluff and Mississippi Alluvial Lands of Louisiana. By W. W. Clendenin, M.S., M.A. Louisiana State Experiment Station, Baton Rouge, La. 32 pp. Cattle Tick and Texas Fever. Second Series, No. 51, Bulletin of the Agricultural Experiment Station of Louisiana State University and A. and M. College, Baton Rouge, La. 1898. 54 pp.

Division of Soils. By Milton Whitney. Reprint from the Yearbook of the Department of Agriculture for 1897. 16 pp. Washington, D. C.: Department of Agriculture.

Commercial Fertilizers. By H. A. Huston. Special Bulletin. May, 1898. Purdue University, H. A. Huston, Lafayette, Ind. 8 pp. Some Interesting Soil Problems. By Milton Whitney. Yearbook of Department of Agriculture for 1897. 12 pp.

Reprint from

Nutrition Investigations in Pittsburg, Pa., 1894-1896. By Isabel Bevier, Bulletin No. 52, U. S. Department of Agriculture, Washington, D. C.

[CONTRIBUTION FROM THE JOHN HARRISON LABORATORY OF CHEMISTRY, No. 30.]

THE ATOMIC MASS AND DERIVATIVES OF SELENIUM.'

BY VICTOR LENHER.

Received June 6, 1808.
INTRODUCTION.

HE following contribution to our knowledge of selenium

THE

was undertaken with the view of studying the various derivatives and reactions of the element, and using such methods or compounds as would prove available in the determination of its atomic mass.

In the series presented, ratios have been determined in compounds differing widely in character and composition, and by methods entirely unlike in nature.

The action of hydrochloric acid gas upon the salts of acid oxides which possess the power of forming volatile compounds with it, affords a clean and accurate method, which can be used in establishing the atomic ratio.

A salt of such a character, when subjected to the action of the gas, yields a substance removed at once from the field of action, while in the vessel which contained the original salt there remains a chloride which can be directly weighed.

Such a method almost completely eliminates the factor of personal error, in that the operator needs but weigh the original 1 Author's thesis for the Degree of Doctor of Philosophy.

salt and the resulting chloride, no manipulation intervening in which he is directly concerned.

If it be possible to use a salt whose resulting chloride can be directly reduced to metal, we have a means of establishing from one salt two series of ratios, which if agreeing, both as individuals. and series, means that a ratio has been established comparable to that existing between the metal and its chloride. If two such series agree, a direct proof is established of the purity of material and accuracy of the method.

An ideal salt for such treatment is a salt of silver; first, since its chloride can be directly reduced to metal by heating in a current of hydrogen gas; second, the ratio between silver and chlorine is one of the most firmly established ratios. Silver selenite is an anhydrous salt, which crystallizes well, is unaffected by light, and is perfectly stable. This substance, when treated. with gaseous hydrochloric acid, yields silver chloride and a hydroxychloride of selenium, corresponding in composition and properties to that obtained by A. Ditte,' when acting on selenium. dioxide with hydrochloric acid gas.

In the first series of experiments, silver selenite was weighed, treated with hydrochloric acid gas, and silver chloride formed, which was weighed. In the second series, silver selenite was weighed, converted into silver chloride, which was weighed, the chloride was reduced in hydrogen to metal, and this again weighed; two ratios were thus established from one sample of selenite by comparison with silver and chlorine, and with metallic silver.

A study of all the known double bromides has been made, and new bromides of rubidium and cesium prepared. Of all the salts examined, the one which seems best adapted for the purpose of an atomic mass series is the ammonium salt. This substance is easily obtained pure and crystallizes well. When treated with hydroxylamine, selenium is set free, and the element itself can be brought on an asbestos filter, washed, dried at 100°, and weighed.

The use of hydroxylamine, according to the method of Dr. Harry F. Keller, for the precipitation of selenium, affords the 1 Ann, chim. phys., (5), 10, 82.

2 Private communication from the author.