192 REPORTS OP inve;stigations and projects. 



An investigation upon the atomic weight of neodymium has been begun by- 

 Mr. H. C. Chapin. Through the kindness of the Welsbach Light Company 

 over 5 kilograms of neodymium ammonium nitrate were available as a start- 

 ing-point. Since it is not possible to separate completely a substance from a 

 less soluble isomorphous impurity by crystallization, search was first made 

 for two solvents such that the impurities which tend to concentrate in the 

 crystals separating from one solvent concentrate in the mother-liquors of the 

 other. This is the case in the crystallization of the double ammonium nitrate 

 from dilute nitric acid, and of the nitrate from concentrated nitric acid. In 

 crystallizing the double ammonium nitrates from dilute nitric acid, lanthanum 

 and praseodymium concentrate in the extreme crystal end, while samarium 

 and gadolinium concentrate in the mother-liquors. Exactly the reverse is 

 true when the nitrates are crystallized from concentrated nitric acid. Many 

 thousand crystallizations have been carried out with some of the material, 

 and some very pure specimens have been prepared. Comparison of the 

 various samples of material will be made by analysis of the chloride. None 

 have as yet been completed. 



Goldthwait, Joel E., Boston, Massachusetts. Grant No. 468. For the 

 chemical study of the (Etiology of the so-called "rheiiinatoid diseases." 



$2,000. 



The object of this grant was to aid in ascertaining the precise chemical 

 nature of the toxins generated by bacteria now known to be one of the 

 principal causes of rheumatoid disorders, with the idea that assistance for 

 bacteriological investigations allied with the study should be obtained from 

 other sources. 



Dr. H. W. Marshall, who has had immediate charge of the work, reports 

 that during the past year investigations have been started upon the subject 

 of chronic non-tubercular arthritis, which must necessarily continue for a 

 considerable period of time before sufficient data can be accumulated to make 

 any authoritative statements possible, but enough has been accomplished to 

 indicate definitely the line of investigation in the future. The class of cases 

 about which the work has centered up to the present time have been those 

 obscure chronic types called rheumatoid arthritis, leaving out of considera- 

 tion undoubted cases of infectious origin, like gonorrheal arthritis and 

 traumatic varieties, or those due to mechanical irritation simply, also the 

 neuropathic kinds represented by Charcot's joints. Clinical material has 

 been obtained from the Massachusetts General Hospital and also from Dr. 

 Goldthwait's private practice. 



While no positive results have been obtained from the work of the year, 

 at the same time data of extreme suggestiveness have developed which 

 promise much in the ultimate solution of the problem. Because of the 



