278 CARNEGIE INSTITUTION OF WASHINGTON. 



and that their work substantiates our theory that both the hydroxyl 

 ion and the nonionized barium hydroxide may be considered active. 

 A large amount of data on the velocity of decomposition of benz- 

 imido ethyl ester and acetimido ethyl ester by sodium ethylate in the 

 presence of sodum iodide and sodium bromide shows that the ''salt 

 catalysis" produced by the sodium iodide in this case is due simply 

 to the change in the percentage of ionization of the sodium ethylate 

 by the sodium iodide. In accordance with the Arrhenius isohydric 

 principle, the sodium iodide changes the percentage of ionization of 

 the sodium ethylate; since the ethylate ions and nonionized sodium 

 ethylate do not have the same activity, there is a change in the reac- 

 tion velocity. Although the "salt effect" in this case is apparently 

 simple, other unpublished data show that in some cases it is far more 

 complex. 



On the reactions of both the ions and the nonionized forms of electrolytes. The reactions 

 of sodium phenolate with methyl iodide and ethyl iodide in absolute ethyl alcohol 

 at 25° and 35°. By H. C. Robertson, jr., and S. F. Acree. American Chemical 

 Journal, 49, 474. 



Dr. Robertson obtained a large amount of quantitative experi- 

 mental material in his study of the reactions of methyl and ethyl 

 iodides with sodium phenolate at 25° and 35°. All of the experi- 

 mental methods, the purification of the materials, the apparatus, the 

 methods of calculation, and the quantitative data are given fully. 

 The results show very clearly that both the phenolate ions and the 

 nonionized sodium phenolate must be reacting with the alkyl halides 

 studied. We have obtained the values Kj = 0.0282, and Km = 0.00474 

 for sodium phenolate and methyl iodide at 25°, Kj = 0.091 and 

 K„j = 0.0131 for sodium phenolate and methyl iodide at 35°, Ki = 

 0.0056 and K„. = 0.00099 for sodium phenolate and ethyl iodide at 25°, 

 and Kf = 0.0184 and K,„ = 0.00323 for sodium phenolate and ethyl 

 iodide at 35°. A discussion of "normal" and "abnormal salt effects" 

 is given. 



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

 Grant No. 888, allotted May 15, 1913. Determination of atomic weights. 

 (For previous reports see Year Books Nos. 3-11.) $1,500 



With the assistance of the above grant, the following researches 

 were carried on under Professor Baxter's direction : 



The investigation upon the atomic weight of lead through the 

 analysis of lead bromide, begun some time ago by Mr. Worsham and 

 Dr. Thorvaldson (see Year Books Nos. 8 and 9), was continued by 

 Mr. F. L. Grover. The salt was fused in atmospheres containing 

 varying amounts of hydrobromic-acid gas and in some cases a small 

 amount of bromine vapor. Then it was dissolved and the bromine 

 content determined either by comparison with silver or as silver bro- 

 mide in the usual way. Hydrolysis during solution with formation 

 of an insoluble basic bromide was prevented by acidifying slightly 



