420 abstracts: electricity and chemistry 



It is of first importance to determine whether the instrument is affected 

 by residual distribution errors. It has been found that a purely elec- 

 trical test can be used for the exact centering of the inside tube, so that 

 any such residual errors due to imperfections of workmanship can be 

 removed. 



At commerical frequencies no error whatever could be detected, due 

 to eddy currents being set up in the tubes by the current in the moving 

 coils. 



Measurements of large currents by means of a current transformer 

 whose ratio had been carefully determined were in substantial agree- 

 ment with the indications of the tubular dynamometer. It is believed 

 that the instrument is accurate to 0.05 per cent. P. G. A. 



ELECTRICITY. — The testing and properties of electric condensers. Cir- 

 cular Bureau of Standards, no. 36. 1912. 

 In the testing of condensers over a period of years, much information 

 haj been collected, only a part of which is at present available to the 

 public. Also, a large amount of work has been done elsewhere, which 

 has appeared in various publications. It is the purpose of this circular 

 to collect together the important facts concerning condensers and to 

 present them as a connected whole. The different kinds of condensers 

 are described and their properties discussed, and the most satisfactory 

 methods of testing indicated. H. L. Curtis. 



CHEMISTRY. — The standardization of potassium permanganate solu- 

 tion by sodium oxalate. R. S. McBride. Bulletin Bureau of 

 Standard, 8 : 612-643. 1912. 

 It was desired to determine the effect of the variation of the following 

 factors upon the result obtained in the standardization of potassium per- 

 manganate by sodium oxalate, viz : temperature, acidity, volume of solu- 

 tion, rate of addition of the permanganate, access of air, presence of 

 added manganous sulfate, and in connection with these, the corrections 

 necessary upon the apparent end-points. In order to accomplish such 

 determination the factors were varied one at a time and the effect, if 

 any, produced upon the apparent value of the permanganate noted. 

 Each of the factors was found to have a definite, though small, influence 

 upon the result. 



The effects were undoubtedly due to a variation of the reaction from 

 the normal course as usually given. Such variations might tend to 

 cause the use of an excess of either permanganate or oxalate; or both 



