210 REPORTS O'e INVESTIGATIONS AND PROJECTS. 



The final results of the research are as follows : 



Although prepared under conditions differing considerably in basicity and 

 acidity, the different samples evidently are of essentially the same composi- 

 tion and may reasonably be assumed to represent tri-silver phosphate free 

 from basic or acid impurities. If the atomic weight of silver is assumed to 

 be 107.88 referred to oxygen 16.000, the atomic weight of phosphorus calcu- 

 lated from the above ratio is 31.04. The results of this investigation will 

 shortly be published. 



The analysis of phosphorus tri-bromide, begun last year by Mr. A. C. 

 Boylston (see Year Book No. 7, p. 191), has been continued by Dr. C. J. 

 Moore, but no final results have been obtained as yet. 



The purification and analysis of neodymium chloride have been continued 

 by Mr. H. C. Chapin. The material for analysis was fractionally crystallized 

 first as double ammonium nitrate from dilute nitric acid, then as nitrate from 

 concentrated nitric acid, the extreme mother-liquor and crystal-fractions be- 

 ing occasionally rejected. The series of fractions in each crystallization num- 

 bered about 20. 103 sets of crystallizations as double nitrate and then 67 as 

 nitrate from nitric acid were carried out. Most of the impurities which ac- 

 cumulate in the crystals in the first process pass into the mother-liquors in 

 the second. In this way it was hoped to free the neodymium from closely 

 related elements more completely than is possible by crystallization as any 

 single compound. 



Of the final series of fractions the 10 nearest the crystal-end from their 

 absorption spectrum seemed to be pure, those nearer the opposite end of 

 the series containing small, gradually increasing amounts of praseodymium. 

 From this final series of fractions several were selected for analysis, adja- 

 cent fractions being combined in order to give sufficient material to handle. 

 The extreme crystal fraction is numbered i. In addition to these samples 

 two fractions, A and B, were removed at different times during the crystalli- 

 zation as double nitrate. These latter fractions were found- to contain traces 

 of praseodymium, which were determined spectrographically by comparison 

 with known amounts of praseodymium. 



The different samples were carefully converted to chloride and were dried 

 for analysis in a current of hydrochloric-acid gas at about 350°. Fusion of 



