Chemistry and Physics. 677 



cyanide that is now extensively used. — Jour. Indust. and Eng. 

 Chem., vii, 433. h. l. w. 



2. Electroplating with Cobalt. — Commercial plating with 

 nickel is an industry of very great magnitude, but although it 

 has been known for a long time that the closely related metal 

 cobalt is capable of yielding similar results, there has been hereto- 

 fore no practical application of this metal in this way, doubtless 

 on account of its greater value due to its use in producing the 

 blue color of glazes used in the ceramic industry, etc. On 

 account of an increased production of cobalt in recent years in 

 the Province of Ontario, there is probably a need of a more 

 extensive utilization of this metal. H. T. Kalmtjs, C. H. Harper, 

 and W. L. Savell, of the Canadian Department of Mines, have 

 made extensive experiments with cobalt plating, and have found 

 that this metal has some advantages over nickel which in practice 

 may overcome its higher cost. One of the best cobalt plating 

 solutions, used with metallic cobalt anodes, is made as follows : 



Cobalt sulphate (anhydrous), 312 grams 



Sodium chloride, 19-6 " 



Boric acid, nearly to saturation 

 Water, 1000 cc 



The cobalt may be deposited on various metals and alloys, and 

 the platings are firm, hard and uniform. They may be buffed to 

 a satisfactorily finished surface having a beautiful luster, which, 

 although brilliantly white, has a slightly bluish cast. An advan- 

 tage of the solution that has been mentioned is that it is capable 

 of plating at least 15 times as fast as the fastest satisfactory nickel 

 solution. It appears that the cobalt plating rapidly deposited is 

 harder than nickel plate, so that less cobalt is required to give 

 the same protection. As the present price of cobalt is about four 

 times that of nickel, it may seem doubtful that the former can 

 replace the latter in practice. The authors, however, claim this 

 to be probable. — Jour. Indust. and Eng. Chem., vii, 370. 



H. L. AV. 



3. The Use of Mercuric Oxide for Standardizing Volumetric 

 Solutions. — M. A. Abelmann finds mercuric oxide a good basis 

 for standardizing, since it can be obtained perfectly pure, and it 

 is stable and not hygroscopic. For purposes of acidimetry it can 

 be dissolved in an excess of ^ normal hydrochloric acid when a 

 sufficient amount of sodium chloride is present and heat is applied. 

 For iodometric standardization the oxide is dissolved with hydro- 

 chloric acid in a closed glass stoppered flask, then an excess of 

 potassium iodide and some potassium hydroxide are added, and 

 then the mercury is precipitated as metal by the use of formalde- 

 hyde. Now, after acidifying with acetic acid, the mercury is 

 dissolved by volumetric iodine solution in excess, and the excess 

 is found by means of sodium thiosulphate solution, using starch 

 as an indicator. — Bulletin, xvii, 9. h. l. w. 



4. A Manual of Practical Physical Chemistry ; by Francis 

 W. Gray. 12mo, pp.211. London, 1914 (Macmillan and Co., 



Am. Jour. Sci.— Fourth Series, Vol. XXXIX, No. 234.— June, 1915. 

 44 



