254 



SCIENCE 



[N. S. Vol. XXXIV. No. 



The method consists in precipitating the lead as 

 chromate, which, when dissolved in hydrochloric 

 acid, liberates iodine from potassium iodide and 

 the iodine is titrated with sodium thiosulphate. 

 A Method of Analysing some Commercial Gold 



Alloys: James O. Handy. 



Gold alloys containing Au, Ag, Cu, Zn and Sn 

 are reduced to filings for analysis. 



0.5 gram is dissolved in aqua regia, 4 HCl : 

 1 HNO3. The excess of acid is boiled off, the 

 liquid is diluted and AgCl precipitated by boiling. 

 Filter, wash, dry and weigh. 



Filtrate plus 5 per cent, of concentrated HCl, 

 is treated with H,S. In the filtrate from the sul- 

 phides, the Zn is separated as carbonate and 

 weighed as oxide. 



The SnS is dissolved out of the sulphide precipi- 

 tate by 30 per cent. HCl, and is again precipitated 

 as SnS after nearly neutralizing with ammonia. 

 Weigh as oxide. 



The Cu is dissolved out of the Au + CuO mix- 

 ture obtained by burning off the sulphides of gold 

 and copper. Concentrated HNO3 is used. H-SOj 

 is added and the HNO3 boiled ofE. After cooling, 

 water and sodium acetate are added. Boil, cool, 

 add EH and titrate Cu by hyposulphite. 



Au and Ag are determined by scorification with 

 lead and borax — silica flux. A ' ' control ' ' assay 

 to check losses of Au and Ag is run with a mix- 

 ture of metals of approximately the formula of 

 the alloy itself. The Au and Ag are determined 

 together and then separated in the usual manner. 

 Results by corrected fire-assay are more exact than 

 by wet methods in most hands. 



Alloys of gold containing up to 26 per cent. Ag, 

 18 per cent. Cu, 7.5 per cent. Zn and 2 per cent. 

 Sn have been successfully analyzed by this method. 



Concentration and Purification of Iron Ore, High 

 in Sulphur, iy Boasting in a Sotary Kiln : 

 James O. Handy. 



division of fertilizer chemistry 



Paul Eudnick, chairman 



J. E. Breckenridge, secretary 



Note on the Neutral Permanganate Method for 



the Availaiility of Organic Nitrogen: John 



Phillips Street. 



Further tests with experimental mixtures, in 

 which the permanganate availability of the nitro- 

 genous material was known, showed that under 

 certain conditions very misleading results were 

 obtained, particularly with certain high-grade am- 

 moniates like dried blood. Investigation showed 



that muriate of potash had no effect on the avail- 

 ability results, but that as the relative amount of 

 acid phosphate was increased the availability of 

 the nitrogenous material decreased, for instance, 

 dried blood from 97 to 59 and tankage from 91 

 to 78. It was found that the addition of one 

 gram of sodium carbonate prior to the introduc- 

 tion of the permanganate solution gave results 

 close to theory with all the materials tested, except 

 garbage tankage which gave somewhat high re- 

 sults, but not high enough to lead to erroneous 

 interpretation of the analysis. 

 The Use of Fused Silica Dishes for Potash Deter- 

 mination in Fertilizers: W. D. Eichardson. 



The Availability of the Insoluble Nitrogen in 

 Certain Commercial Fertilizers: B. L. Hart- 

 well and F. E. Pember. 



Eesults secured by growing crops in pots showed 

 that the insoluble nitrogen of twelve potato fertil- 

 izers made by different manufacturers must have 

 been derived from fairly high-grade material. 

 The availability of this nitrogen was found to be 

 about the same both by the crop results and by 

 the alkaline permanganate method recently adopted 

 by certain northeastern states for the laboratory 

 determination of the character of the materials 

 used as sources of the insoluble nitrogen of fer- 

 tilizers. 



The Use of Alundum Crucibles for Total Phos- 

 phoric Acid and Potash Determinations in Fer- 

 tilizers: W. D. Eichardson. 

 The Availability of Nitrogen in Complete Fertil- 

 izers: Jacob G. Lipman. 

 Notes on Estimation and Valuation of Potash: 

 P. F. Trowbridge. 



Eeports from the following committees were 

 received and will be published in the Journal of 

 Industrial and Engineering Chemistry : Paul Eud- 

 nick, for the committee on nitrogen; G. A. Farn- 

 ham, for the committee on phosphoric acid; J. E. 

 Breckenridge, for the committee on potash; C. F. 

 Hagedorn, for the committee on phosphate rock; 

 F. B. Carpenter, for the committee on fertilizer 

 legislation. 



DmsiON of pharmaceutical chemistry 



B. L. Murray, chairman 



F. E. Eldred, secretary 



A Few Eesults Obtained from Pepsin Assay: O. 



P. Eyre. 



Observations upon the Assay of Digestive Fer- 

 ments: Howard T. Gbaber. 



