302 



SCIENCE 



[N. S. Vol. XXVII. No. i 



The Influence of Teniperature on the Elec- 

 trolytic Precipitation of Copper from 

 Nitric Acid: James R. Withrow. 

 In determining copper in presence of 

 nitric acid by the older electrolytic meth- 

 ods (without agitating the electrolyte) it 

 was found upon a number of occasions that 

 the nearly complete deposits would disap- 

 pear from the cathode. 



The trouble was traced to accidental 

 fluctuations in the temperature. Copper 

 dissolves in nitric acid more readily at 

 elevated than at ordinary temperature. 

 Therefore, if the current strength is suffi- 

 ciently low the solvent influence of rising 

 temperature soon exceeds the ability of the 

 current to deposit the metal. 



The rate of electrolytic precipitation 

 of copper was, therefore, determined at 

 a number of temperatures, using a cur- 

 rent of low intensity, so as to find just 

 what this temperature etfeet was. Pre- 

 liminary to this, however, it was necessary 

 to determine the rate of precipitation 

 from varying amounts of nitric acid. 

 The most favorable amount of acid was 

 then used in the elevated temperature ex- 

 periments. 



It was found that nitric acid increasing- 

 ly retards precipitation even from the 

 smallest amounts upwards. The use of 

 small quantities, however, is advantageous 

 because of the beneficial effect on the char- 

 acter of the deposits. 



Using 0.2 per cent, (by volume) of 

 nitric acid, it was found that increasing 

 temperature accelerated the precipitation 

 until 60° C. was reached. Beyond 70° C, 

 towever, the influence was a retarding one. 

 This "turning temperature" will of course 

 vary with the current strength. 



Action of Certain Oxidizing Agents upon 

 Hydrazine Sulphate: F. P. Sheterlt. 

 Reported by title. 



The Electrolytic Formation of Selenic 

 Acid from Lead Selenate: F. C. Ma- 

 thers. Reported by title. 



The Reaction Produced by Heat upon « 

 Mixture of Ammonium Chloride and 

 Potassium Bichromate: G. B. Frank- 

 FOETER, E. V. Manuel and V. H. 

 RoEHRiCH. Reported by title. 



Action of Water on Galvanized Iron: "W. 

 F. MoNTORD. Reported by title. 



The Preparation of Silicon Tetrachloride: 

 Chables R. Sanger. Reported by title. 



The Preparation and Properties of Pyre- 

 sulphol Chloride and Chlorosulphonic 

 Acid: Charles R. Sanger. Reported 

 by title. 



Recent Improvements in the Determina- 

 tion of Small Amounts of Arsenic and 

 Antimony: Charles R. Sanger. Re- 

 ported by title. 



The Determination of Small Amounts «f 

 Fluorine: Charles R. Sanger. 



Sodium Alum: W. R. Smith. Reported 

 by title. 



Some New Compounds of Hydrazine: J. 

 "W. Turrentine. Reported by title. 



Fractionation of the Yttri%im Earths: B. 

 D. Hall. Reported by title. 



The Rare Earth Bromates—A New Method 

 of Separation of the Yttrium Earths: 

 Charles James. Reported by title. 



A Scheme for the Separation of the Rare 

 Earths: Charles James. Reported by 

 title. 



A Study of Graphitic Acid: G. B. Frank- 

 FORTER and Lillian Cohen. Reported 

 by title. 



B. E. CURRT, 



Press Secretary 

 (To he continued) 



