Chemistry and Physics. 97 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Quantitative Determination of Copper. — For the rapid 

 determination of copper, Alexander Boyer uses hydroxylamine 

 hydrochloride in the presence of sodium hydroxide and Rochelle 

 salt, thus precipitating cuprous oxide, which is filtered on an 

 asbestos filter in a glass tube, washed with hot water, dried, ig-- 

 nited in a stream of air, and weighed as cupric oxide. With about 

 0*3 g. of copper in the form of sulphate, he recommends the use of 

 a porcelain dish of about 200 cc capacity, the addition of 17 g. of 

 sodium potassium tartrate and 4 g. of sodium hydroxide, both in 

 rather strong solution, then heating to boiling and adding about 

 2 CC of a 5 per cent solution of the hydroxylamine salt, and boiling 

 for about a minute. He shows by very satisfactory test analyses 

 that considerable quantities of antimony, zinc, bismuth, lead, iron, 

 arsenic, tin, ammonium, and nitrates do not interfere with the 

 method. For analyzing alloys, such as bronze and brass, he dis- 

 solves in nitric acid, evaporates to fuming with sulphuric acid, 

 neutralizes with sodium hydroxide, and proceeds as usual. In 

 cases where manganese, nickel and cobalt may be present, he 

 recommends first precipitating with hydrogen sulphide in sul- 

 phuric acid solution and then treating the resulting sulphides in 

 the same way as the alloys. Silver interferes with the method 

 and must be previously removed. Mercury is also precipitated, 

 but it is driven off upon ignition. — Zeitschr. analyt. Chem., \\ r 

 729. h. l w. 



2. The Dissoeiatio?i of Phosphorus Vajior. — Biltz and Victor 

 Meyer have shown that at lower temperatures phosphorus vapor 

 corresponds to the formula P 4 and they were able to detect dis- 

 sociation at higher temperatures. Victor Meyer's method is y 

 however, not suitable for the quantitative investigation of disso- 

 ciating vapors, since the degree of dissociation is altered by the 

 presence of an inert gas. Stock and Gibson have thereforedeter- 

 mined the pressure temperature curves of phosphorus vapor at 

 various volumes, using a quartz apparatus, and have found that 

 the vapor density corresponds to P 4 up to 700° C, above which 

 dissociation takes place according to the equation P 4 = 2P 2 . 

 There is no evidence of further dissociation at the temperatures 

 investigated, and the law of mass action applied to the new meas- 

 urements decides against the equation P 4 = 4P. — Chem. News, 

 cvi, 129. h. l. w. 



3. The Contamination of Laboratory Samples by Iron Derived 

 from Crushing Machinery. — Victor Lenher has determined 

 the amount of finely divided iron introduced into several samples 

 of quartzite by grinding small fragments in a Braun crusher to 

 pass a 120 mesh screen. The amount of this contamination varied 



Am. Jour. Sci.— Fourth Series, Vol. XXXY, No. 205.— January, 1913. 



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