Chemistry and Physics. 251 



known weight of zinc in acid have obtained the value 65*50 for 

 the atomic weight of this metal. This method has the advantage 

 of being independent of any other atomic weights. — J. Chem. 

 Soc, li, 854, Dec, 1887. G. f. b. 



6. A Text-book of Inorganic Chemistry. — By Prof. Victor 

 voisr Richter. Authorized translation by Prof. Edgar F. Smith. 

 Third American from the fifth German edition. 12mo, pp. xvi, 

 428. Philadelphia, 1887. (P. Blakiston, Son & Co.)— This book 

 has been for some time in the hands of American readers, and the 

 demand for a third edition is evidence that it has been well re- 

 ceived. In the thirty pages of introduction, the author sketches 

 the province of chemistry, its symbols 'and formulas, the principles 

 of energy, and the conservation of energy, the energy-relations of 

 chemical changes and crystallography. The elements are then 

 taken up, beginning with hydrogen, and the philosophy of chem- 

 istry is gradually worked in as it is required. For instance, after 

 the hydrogen compounds of the halogens, the law of definite pro- 

 portions, the atomic theory, and the volume relations of the ele- 

 ments ai*e discussed. A hundred pages later come atomic and 

 molecular values, valence and chemical structure; and at the close 

 of the non-metallic groups, the periodic system is considered. An 

 excellent feature of the book is the considerable space given to 

 the energy relations of chemical changes, particularly to heat re- 

 lations. The distinction drawn by Berthelot between epothermic 

 and endothermic reactions is emphasized and the great importance 

 of such reactions as H + C1=HC1 + 22000 cal. and H + I=HI— 7000 

 cal. is maintained firmly. We are glad to note an extension of 

 this thermal discussion, as well as of other physical relations, in- 

 timately associated with chemistry, in this third edition. The 

 section on Mendelejeff's periodic system of the elements is care- 

 fully written and gives an excellent account of this remarkable 

 classification. In an appendix is given the heat of formation of 

 the most important metallic compounds according to J. Thomsen. 

 Dr. Smith has performed well the part of a translator, although a 

 want of perfect smoothness in flow sometimes betrays the diffi- 

 culties he has had to contend with. The printing and mechanical 

 work are good, but the woodcuts seem hardly up to the standard 

 of the rest of the book. G. f. b. 



7. A Manual of Analytical Chemistry • by John Muter. 

 Third edition. 200 pp. Philadelphia, 1887. (P. Blakiston, Son 

 & Co.). — Muter's Analytical Chemistry appears in the third edi- 

 tion in compact form but enlarged in scope. Of the host of 

 works of its kind, dealing simply with the outlines of the subject, 

 it is one of the fullest and best. 



8. A new instrument for measuring heat. — Prof. Weber at a 

 meeting of the Helvetii Society of Sciences described the follow- 

 ing very sensitive micro-radiometer. One arm of a Wheatstone 

 bridge is formed by a thin tube, which is filled in its middle part 

 with mercury, and at its ends, for about 5 mm , with a solution of 

 zinc sulphate. To each end of the tube is fitted a metallic case, 

 one side of which consists of a plate of rock salt. This case is 



