Chemistry and Physics. 399 



Upon treating the mass with water the alkali used in the process 

 goes into solution, largely as silicate. It is then causticized with 

 lime, and, after filtering off the resulting calcium silicate, the 

 liquid is evaporated and the alkali is used again for the treat- 

 ment of feldspar, with a total loss of only about l^c, according 

 to the experiments of the authors, working on a small scale. 



The residual artificial leucite gives up its potassium very 

 readily to dilute acids, so that the point where the potassium 

 is extracted can be detected by an indicator, such as methyl 

 orange. It is possible, therefore, to extract the potassium as 

 chloride, sulphate or nitrate by the use of the corresponding 

 acids without attacking the aluminium in the compound. The 

 residue, now filtered from the potassium salt solution, resembles, 

 kaolinite somewhat in cotaposition, but it is readily decomposed 

 by sulphuric acid with the formation of aluminium sulphate and 

 gelatinous silica. After dehydrating the silica by drying, the 

 two things may be separated by treatment with water and 

 filtration. — Jour. Indust. Eng. Chem., ix, 935. 



H. L. w. 



2. Electrochemical Equivalents; by Carl Hering and Fred- 

 erick H. Getman. 12mo, pp. 130. New York, 1917 (D. Van 

 Nostrand Company). — This little book gives an excellent table 

 of electrochemical equivalents for practically all of the known 

 elements. The international atomic weights of 1917 are used 

 as the basis, and the equivalents are calculated for all the possible 

 valences or changes of valence in each case. The values given 

 are in terms of milligrams per coulomb, coulombs per milligram, 

 grams per ampere-hour, ampere-hours per gram, pounds per 

 1000 ampere-hours, and ampere-hours per pound. The data just 

 mentioned are given in the principal table, but there are several 

 other tables containing useful information. While the book does 

 not profess to be a treatise on electrochemistry, sufficient 

 explanatory text is given to permit the use of the data without 

 need of reference to other works. There are discussions of 

 fundamental laws and data, the methods of calculation are clearly 

 explained and illustrated by numerous examples, the principles 

 of electrolysis and the electronic theory are well presented, while 

 in the appendix the subject of valence and chemical calcula- 

 tions are taken up. The book appears to be a very useful one, 

 not only for the purposes of practical electro-chemical calcula- 

 tions, but also as a reliable and concise source of theoretical 

 information in the field where chemical and electrical sciences 

 are connected. h. l. w. 



3. A Laboratory Manual of General Chemistry ; by William 

 J. Hale. 12mo, pp. 474. New York, 1917 (The Macmillan 

 Company). — This book presents an unusually extensive and 

 advanced course of laboratory work. The experiments are not 

 only very numerous, but there are some rather elaborate quanti- 



