CHEMISTRY — RICHARDS. 221 



(6) The Heat of Combustion of Pure Organic Substances: 



Concerning this subject a comprehensive investigation completed last year 

 with the help of Dr. R. H. Jesse, jr., was discussed in the last report and has 

 since been published in full. This research is now being continued with the 

 assistance of Mr. F. Barry; and the novel apparatus and methods used in 

 the previous work have continued to yield admirably consistent results. The 

 data already secured, together with those to be obtained in the future, will, 

 it is hoped, form a more satisfactory basis for the comparison of the internal 

 energy-changes of these substances than any other data thus far available. 



(7) The Compressibility of Ice: 



In the last report it was pointed out that the compressibility of ice is a 

 datum of much interest, and the execution of a preliminary determination 

 was announced. During the past winter, with the assistance of Prof. C. L. 

 Speyers, this matter has been carried much further, and the quantity in 

 question has been determined with considerable accuracy. According to one 

 method, the compressibility of ice at — 7° C. was found to be 0.0000118, and 

 according to another 0.00001 16, between 100 and 500 megabars, if the com- 

 pressibility of mercury under like conditions is taken as 0.0000037. The 

 outcome is surprising. One might have expected the compressibility of ice 

 to be greater than that of water, since as a general rule the phase of any 

 given substance possessing the greater volume has also greater compressibil- 

 ity. Thus the substance water forms an exception in this respect, as in so 

 many others, to the general rules usually governing the physical properties 

 of solid and liquid substances. 



(8) The Surface-Tensions of Liquid Substances: 



In connection with the comprehensive research upon the compressibility 

 of liquids discussed in a previous report, Professor Speyers has also deter- 

 mined the surface-tensions of liquid substances ; because compressibility has 

 been shown by Richards and Mathews, as well as by other investigators, to 

 be fundamentally connected with surface-tension. In the course of this new 

 work upon surface-tension it has been found that many previous investiga- 

 tions have been inadequate because of the still remaining slight "capillary" 

 cfifect of the walls of even fairly wide containing-vessels. As a rule, in the 

 past, experimenters have not used vessels nearly wide enough to eliminate 

 this source of error. The careful study of the surface-tension of a number 

 of liquids whose compressibilities have also been determined at different 

 temperatures and in tubes of different sizes promises to throw light upon 

 the whole subject, including the relation between surface-tension and com- 

 pressibility. 



It has already been pointed out that many of these investigations are 

 already in print or in press. References to these will be found in the Bibli- 

 ography of this Year Book (page 51). The others will be cast into shape 

 suitable for publication as soon as circumstances will permit. 



