154 REPORTS ON INVESTIGATIONS AND PROJECTS. 



hj-droh'sis of ammonium acetate at a temperature of 306° by the method 

 described in preceding reports, which consists in determining the increase 

 produced in the conductivity of the salt by the addition to it of one of its 

 hydrolytic products, acetic acid or ammonium hydroxide. From these 

 results the ionization of water at 306° has been derived. An entirely simi- 

 lar investigation of the magnitude of this ionization at ordinary temper- 

 atures has also been completed by Mr. C. W. Kanolt, and has yielded results 

 in good agreement with those previously obtained by entirely independent 

 methods. Finally, good progress has been made in the development of the 

 new apparatus for extending the conducti\'ity measurement up through the 

 critical temperature ; and also in the development of the method for deter- 

 mining the hydration of ions by transference experiments, but final results 

 have not j-et been obtained. 



Richards, Theodore W», Harvard University, Cambridge, Massachusetts. 

 Grant No. 326. Investigatio7i of the values of atomic 7veights, etc. (For 

 previous reports see Year Book No. 2, p. xxxii ; Year Book No. 3, p. 

 112. and Year Book No. 4, p. 155.) $2,500. 



Abstract oj Report. — The full records of two of the investigations described 

 in the last report have been published as Publications of the Carnegie Insti- 

 tution of Washington, Nos. 56 and 61, occupying 68 and 43 pages respect- 

 ively. These are entitled ' ' Energy changes involved in the dilution of zinc 

 and cadmium amalgams ' ' and ' ' The electromotive force of iron under varj- 

 ing conditions and of its occluded hydrogen." The other investigations 

 outlined in that report which have not already been published are now being 

 prepared for publication. 



The following investigations were wholly or partially supported by grants 

 from the Institution. 



(i) A revision of the atomic weight of potassium by the analj'sis of potas- 

 sium chloride was carried out with the assistance of Dr. Arthur Staehler, 

 assistant in the First Chemical Institute of the University of Berlin, on leave 

 of absence for a year of study in Harvard University. This research was 

 modeled essentially on the lines of that upon sodium. (Publication of the 

 Carnegie Institution of Washington No. 28.) Great care was taken in the 

 preparation of the material and the analysis. The results were as concordant 

 and convincing in this new research as in the previous one, and uncovered 

 as before small errors in the work of Stas. The molecular weight of potassic 

 chloride was referred to the weight of silver just needed to precipitate its 

 chlorine, as well as to the weight of silver chloride. The two methods gave 

 essentially the same result, the former giving K — 39.114, and the latter 

 K = 39. 1 13, if CI = 35.473 and Ag = 107.930. The close agreement of the 

 results confirms the previous Harvard work upon chlorine. (Publication 

 of the Carnegie Institution of Washington No. 28.) 



