JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. 11 February 4, 1921 No. 3 



PHYSICS.— r/z^r .compressibility of diamond.'^ L. H. Adams, Geo- 

 physical Laboratory, Carnegie Institution of Washington. 



Many of the properties of that remarkable form of carbon, the 

 diamond, are known, but its compressibility has never been measured. 

 The commercial value of a quantity of diamonds sufficient for such a 

 determination is so great that the opportunity for making the deter- 

 mination would seldom present itself. It is not necessary for this 

 purpose, however, that the material be in one piece or even in large 

 fragments although, contrary to what is commonly believed, no ap- 

 prehension need be felt in subjecting diamonds or any other homo- 

 geneous material to the enormous pressures required. - 



It was the writer's good fortune to have at his disposal about 80 

 grams of diamond chips obtained through Dr. F. E. Wright, of this 

 Laboratory, from S. L. Van Wezel, Inc., of New York City.^ The 

 material was in the form of clear, colorless fragments of various sizes 

 up to one or two millimeters in their largest dimension. A small 

 amount of metallic impurity was found to be present and was removed 

 by treatment with hot nitric acid. After being washed with water 

 and dried in the oven, a fraction consisting of about 30 grams of the 

 coarser fragments was separated from the remainder and was used 

 for the measurement of the compressibility. 



The method used has been described in a former publication^ from 

 this Laboratory. Briefly, it is as follows: The material to be investi- 

 gated is surrounded by kerosene and placed in a cylindrical, heavy- 

 walled, steel bomb, one end of which is closed while in the other 

 end is fitted a piston with a suitable packing. Pressure is applied 



' Received January 8, 192L 



- As long, of course, as the pressure is strictly hydrostatic, that is, uniform in all direc- 

 tions. 



3 Our thanks are due to this firm and especially to the President, Mr. M. S. Van Wezet, 

 for their courtesy in lending this material. 



"• L. H. Adams and E- D. Williamson, Journ. Amer. Chem. Soc. 41: 12-42. 1919. 



45 



