66 Scientific Intelligence. 



maximum is variable somewhat with the conditions, the volume 

 of the solution affecting the result, up to a certain point. In 

 proof of this he exposed crystals of alum and of magnesium sul- 

 phate, after they had reached this maximum size, to strongly 

 supersaturated solutions for several days, without any result. 

 This maximum size of a crystal, however, depends upon the pres- 

 ence of foreign substances in the solution, a crystal of salt being 

 larger when obtained from a solution containing cupric chloride. 

 — Zeitschr. physikal. Chem., ix, 267, April, 1892. G. f. b. 



2. On the Resolution of Lactic Acid into Optically active 

 Constituents. — Although the asymmetric carbon theory of Van't 

 Hoff was suggested to him by the isomerism of lactic and sarco- 

 lactic acids, no experimental proof has until now been given that 

 inactive lactic acid is actually composed of two optically active 

 lactic acids. This proof is furnished by Purdie and Walker, 

 who have effected the resolution of lactic acid by fractional crys- 

 tallization of the strychnine salt. Commercial lactic acid was 

 diluted and boiled with water to convert the anhydride present 

 — about 31 per cent — into acid. In the calculated quantity of 

 this acid 460 grams of strychnine were dissolved, and the neutral 

 solution thus obtained was submitted to fractional crystallization. 

 Three crops of crystals were obtained which were dissolved sepa- 

 rately in water and treated with ammonia in slight excess. The 

 filtered solution made up to the same concentration gave rotations 

 in a 200 ,nm tube of + 5-46°, +4-83° and —1-33°. The first solution 

 was boiled with zinc oxide and fractionally crystallized. The 

 first crop of crystals proved to be the pure zinc salt of lsevo-lactic 

 acid, and gave a specific rotation [«] D = + 5*63. The rotation 

 of the acid is opposite in direction to that of its salts. The 

 mother liquors were converted into zinc salts, and by successive 

 crystallization pure zinc dextrolactate was obtained having a 

 specific rotation [a] D = — 5 - 7l°. By mixing equal weights of 

 the solutions of these two zinc salts, the authors obtained a solu- 

 tion which was optically inactive and which deposited crystals of 

 ordinary zinc lactate. — J. Chem. iSoc, lxi, 754, Aug. 1892. 



G. F. B. 



3. On the new element Masrium. — In examining a native 

 fibrous alum from Egypt, Richmond and Off have detected 

 what appears to be a new element. The alum also contained 

 from 1-02 to 3*63 per cent of cobalt. To extract the new sub- 

 stance, 100 kilograms of the mineral were dissolved in water, 

 acetic acid and sodium acetate were added, and hydrogen sulphide 

 was passed through the solution. A white precipitate was thrown 

 down, which was filtered off, well washed, extracted with dilute 

 hydrogen chloride, boiled with aqua regia, diluted and filtered. 

 On cooling a little calcium sulphate separated. This was re- 

 moved and the solution was evaporated to dryness, taken up with 

 dilute hydrogen chloride and precipitated with ammonia. The 

 washed precipitate was dissolved in sulphuric acid and crystal- 

 lized from 50 per cent alcohol. A second crystallization gave a 



