224 REPORTS OF INVESTIGATIONS AND PROJECTS. 



surface of the earth, but also because of the theoretical importance of the 

 volume changes exhibited by this remarkable substance. Accordingly, the 

 careful study of the compressibility of ice was undertaken, with the help of 

 Professor Speyers. No great difficulty was found in executing the deter- 

 mination at — 7° C, by means of a method similar to that described in Pub- 

 lication No. 7, but more results are needed before a final statement of the 

 value can be given. 



Another important unfinished investigation is the continuation of the study 

 of ammonium bromide, conducted with the assistance of Messrs. F. B. 

 Coffin and G. S. Tilley. It was found that ammonium bromide has a decided 

 tendency to occlude ammonia and that the preparation of that substance in a 

 typical state is by no means easy. Until more precise means of assuring 

 definiteness of composition has been obtained, the report of the final results 

 can have little significance. The careful alkalimetric study of the solutions 

 of the salt with the help of the theory of electrolytic dissociation, taking due 

 account of hydrolysis, promises to solve the difficulty when more accurate 

 determinations of conductivities and more precise study of indicators has 

 been completed ; and the work will be prosecuted in these directions. Other 

 work concerning atomic weights, as well as heats of reaction and compressi- 

 bilities, will be undertaken also. 



A number of the previous investigations have appeared in print during the 

 past year, at least in part. Reference to these publications will be found in 

 the Bibliography. 



GEOLOGY. 



Chamberlin, Thomas Chrowder, University of Chicago, Chicago, Illinois. 



Grant No. 571. Inquiry into the fundamental problems of geology. 



(For previous reports see Year Books Nos. 2, 3, 4, 5, 6, and 7.) $4,000. 



During the institutional year ending October 31, 1909, eight papers were 



finished and published. Six of these constituted a correlated group relating 



to those phases of the tidal problem which have cosmogonic and geologic 



bearings, as follows: 



The former rates of the earth's rotation and their bearings on its deformation, by T. C. 



Chamberlin. 

 The rotation period of a heterogeneous spheroid, by Charles S. Slichter. 

 On the loss of energy by friction of the tides, by William D. MacMillan. 

 On certain relations among the possible changes in the motions of mutually attracting 



spheres when disturbed by tidal interactions, by F. R. Moulton. 

 Notes on the possibility of fission of a contracting rotating fluid mass, by F. R. Moulton. 

 The bearing of molecular activity on spontaneous fission in gaseous spheroids, by T. C. 



Chamberlin. 



There was also published a paper on geophysical theory under the planet- 

 esimal hypothesis, by Dr. Arthur C. Lunn ; also a paper on the relations of 

 equilibrium between the carbon dioxide of the atmosphere and the calcium 



