Chemistry and Physics. 145 



SCIENTIFIC INTELLIGENCE 



I. Chemistry and Physics. 



1. A New Cyanide. — W. S. Landis has given an interesting 

 account of the recent development of the commercial prepara- 

 tion of cyanide from calcium cyanainide at Niagara Falls. 



After the successful fixation of atmospheric nitrogen by bring- 

 ing this gas into contact with hot calcum carbide, CaC 2 , with the 

 formation of the cyanainide, CaNCN, and free carbon, work 

 was carried on in Germany for about 15 years in the effort to 

 manufacture cyanide from the cyanamide. The most promising 

 method appeared to be fusion with sodium chloride, but the 

 process was not a commercial success on account of difficulties in 

 carrying it out and the low yields of cyanide obtained. 



In 1916 the supply of sodium cj'anide in this country became 

 very small and its price very high, so that an attempt was made 

 at Niagara Falls, where a cyanamide plant was in successful 

 operation, to manufacture cyanide from this material by fusing 

 it with sodium chloride. By means of improvement in the 

 process, such as the addition of a little calcium carbide to prevent 

 frothing, and rapid heating to a higher temperature for a shorter 

 time, cyanide was produced on a larger scale of a much higher 

 grade than the Germans had ever hoped for. Within a year the 

 process was further improved and the product made still better. 

 Since that time cyanide has been manufactured on a very large 

 scale, equivalent to the production of 4,000,000 lbs. of sodium 

 cyanide per year, and of a grade corresponding to about 35% of 

 sodium cyanide. Even richer products than this have been 

 obtained, and it is expected that the quality will be considerably 

 improved in the future. 



The product has proved itself very satisfactory for use in gold 

 extraction, for the preparation of sodium ferro-cyanide, and for 

 other purposes, so this development may be regarded as a remark- 

 able triumph of the American electrochemist. — Trans. Amer. 

 Electro-chem. Soc. 38 (1920). h. l. w. 



2. A Very Sensitive Reaction for Copper. — Pierre Thomas 

 and Georges Carpentier have found that the alkaline solution 

 phenolphthalin (the colorless reduction-product of the well- 

 known indicator phenolphthalein) which was used by Kastle for 

 the detection of vegetable oxydases and afterwards recommended 

 by Meyer as a test for blood, is, under proper conditions, an 

 exceedingly delicate reagent for copper. The reagent was pre- 

 pared by dissolving 2g of phenolphthalein and 20 of pure potash 

 in 100 cc of water and boiling the solution with lOg of zinc-dust 

 until colorless. To 10 cc of very dilute solutions of copper four 

 drops of the reagent were added and then a drop of hydrogen 

 peroxide solution of a strength corresponding to 5 or 6 volumes 



