Chemistry and Physics. 87 



found that where the use of rubber stoppers and tubing is avoided 

 it is possible to produce a cathodic vacuum by this method. The 

 article under review states that the liquid air, a supply of which 

 is necessary for this process, can now be purchased in London for 

 less than 50 pf. per kg, and that it is becoming more easily 

 obtainable in Germany. — Berichte, xxxvi, 3456. h. l. w. 



4. A Method of Crystallizing difficultly Soluble Substances. — 

 A. de Shulten employs for the purpose under consideration a 

 process which consists in mixing, very slowly, hot, dilute solutions 

 of two substances which give the substance sought by double 

 decomposition. 



For example, a solution of 10 g of BaCl 2 # 2H 2 in 3 liters of 

 water, to which are added 300 cc of concentrated HC1, is heated in 

 a flask on a water- bath, and into this are allowed to fall drop by 

 drop, at the rate of one or two drops per minute, 2 liters of a 

 solution of sulphuric acid containing 2 s of the acid per liter. 

 After 24 hours the first crystals of barite appear at the bottom of 

 the flask, and they increase gradually without the formation of 

 any precipitate. At the end of a month 8 or 9 g of barite are 

 formed. By the same process alumina is deposited in the form 

 of hydrargillite. The author has obtained several other artificial 

 minerals in this way, including celestite, anglesite, haidingerite, 

 erythrite, annabergite, and scheelite.- — Comptes Rendus, cxxxvi, 

 1664. h. l. w. 



5. Fractional Distillation; by Sydney Young. 12mo, pp. 

 234. London, 1903 (Macmillan and Co.). — This book has been pre- 

 pared with the hope that the solution of the difficulties which so 

 often occur in carrying out a fractional distillation may be ren- 

 dered easier, and that the value and economy of highly efficient 

 still-heads in laboratory work may come to be more widely recog- 

 nized than is generally the case at present. It is an excellent 

 treatise on the subject, and chemists will find it interesting as 

 well as useful. h. l. w. 



6'. Flektro-Metallurgie ; von Dr. W. Bouchers, Dritte Auflage, 

 Zweite Abtheilung. 8vo, pp. 289 to 578. Leipsic, 1903 (S. Hirzel). 

 — The first part of this book was noticed in this Journal about a 

 year ago. The second part now under consideration completes 

 the work. It treats of silver, gold, zinc, cadmium, mercury, 

 tin, lead, bismuth, antimony, vanadium, chromium, molybdenum, 

 tungsten, uranium, manganese and iron, as well as of carbides and 

 silicides. The work is a very important and valuable contribu- 

 tion to the theoretical and practical knowledge of this rapidly- 

 developing branch of industry. h. l. w. 



7. A New Form of Galvanometer. — One hardly expects to 

 find in the description of new galvanometers a radical departure 

 from old types, yet the instrument devised by W. Einthoven of 

 the physiological laboratory of the University of Leyden justi- 

 fies the title of a new galvanometer. It consists of a silvered 

 quartz fiber of extremely small diameter, 2*1 p diameter, which is 

 stretched between the poles of a magnet. When the magnetic 



