338 CARNEGIE INSTITUTION OF WASHINGTON. 



solution, the yellow qiiinoid form (F) is changed into the yellow mono- 

 basic salt (G) alone until about 85 per cent of the phthalein is neu- 

 tralized ; then the yellow monobasic salt (G) is changed into the deep red 

 dibasic salt (H). The chief source of color, then, is shown to be the 

 dibasic quinonephenolate salt (H) and not the monobasic quinone salt 

 (F), as assumed formerly by others. This experiment is so striking that 

 it can never be forgotten by anyone interested in the theory of indica- 

 tors. We are making a full study of the affinity and equilibrium 

 constants of the acid and salts by physical-chemical and colorimetric 

 methods and are investigating the chlor, brom, iodo, and other deriva- 

 tives, and the corresponding phthalins. 



Further work by Dr. H. A. Lubs and Mr. E. Hyatt Wight on the tauto- 

 merism of the urazoles has shown that the l-phenyl-3-methylsulphon- 

 5-oxyurazole displays the widest range of tautomeric possibilities yet 

 discovered. The silver salt and ethyliodide give nearly pure 0-ester, 

 whereas the sodium salt and ethyliodide give nearly pure N-ester. 

 A large number of salts and esters have been investigated and full 

 reports will appear later. 



Dr. W. F. Clarke has continued further investigations on the hydro- 

 gen electrode, calomel electrode, and contact potential and has shown 

 that he can reproduce the electrodes to within 0.00001 volt. 



Baxter, Gregory P., Harvard University, Cambridge, Massachusetts. Determi- 

 nation of atomic weights. (For previous reports see Year Books Nos. 3-12.) 



At the beginning of last October the T. Jefferson CooHdge Jr. Memo- 

 rial Laboratory for quantitative analysis was opened, and all the 

 researches carried on with the assistance of this grant were conducted in 

 this laboratory under conditions ideal for the purpose as regards clean- 

 liness and convenience. The various investigations were as follows: 



The Atomic Weight of Lead. 



This research is a continuation of work begun by Mr. Worsham and 

 Dr. Thorvaldson, and taken up anew somewhat over a year ago by 

 Mr. Fred L. Grover (see Year Books Nos. 8, 9, and 12). Mr. Grover 

 has completed the analysis of lead bromide, as described in Year Book 

 No. 12. The results are given in the table on the next page. 



A preliminary series of twelve closely agreeing analyses of lead bro- 

 mide made by Dr. Thorvaldson yielded an average result identical 

 with Mr. Grover's. Because Dr. Thorvaldson's work was essentially 

 pioneering, the detailed data are not given here. 



Mr. Grover also undertook the analysis of lead chloride, since the 

 earlier results obtained by Baxter and Wilson (see Year Book No. 6) 

 are somewhat lower than those yielded by the bromide analyses. 

 Under certain conditions (high concentration and high temperature) 

 lead chloride which has been crystallized from slightly acid solution 

 or fused in an atmosphere of dry hydrochloric-acid gas was found to 

 yield an insoluble basic chloride by hydrolysis when dissolved in water. 



