214 BRIDGMAN. 



The range of values is nearly as great as for bismuth. Here the 

 temperature coefficient of compressibility is greater for that direction 

 in which the linear compressibility is less, although the pressure 

 coefficient of compressibility is less in this direction, as is to be expected. 



For the initial value of the compressibility of antimony of density 

 6.71 Richards gives 24 X 10~ 7 . If there is no error, the significance 

 of this result, when compared with that above, is merely that the two 

 methods of casting adopted above did not bring out the extreme 

 possible difference in the orientation of the crystalline grains. 



Cadmium. Runs were made on three different samples. The first 

 two were made from chemically pure cadmium from Eimer and 

 Amend. The first was extruded at a temperature slightly below the 

 melting point from a diameter of 1.2 to 0.6 cm., and was annealed at 

 230° for ten or fifteen minutes. Its density as 20° was 8.652. The 

 second came from the same source and was cast in a graphite mold, 

 preheated above the melting point, and the casting was cooled by 

 lowering the mold slowly into water, and annealed after casting, as 

 above. The density at 20° was 8.644. These two pieces were ma- 

 chined to a length of 16 cm. and mounted as compression specimens 

 in the apparatus for direct measurement without magnification. 



The source of the other specimen was Kahlbaum, his "K" grade. 

 This is known to have only a few hundredths of per cent of impurity. 

 This was cast in a special manner. The metal was melted in a tube 

 of pyrex glass of diameter about 0.6 cm. in a cylindrical electric furnace 

 mounted with its axis vertical. After temperature equilibrium was 

 attained the glass tube was lowered slowly through the bottom of the 

 furnace into the air of the room, thus allowing the metal in the lower 

 part of the tube to solidify. The lowering was accomplished by clock- 

 work, and was at the rate of about 12 cm. per hour. It will be seen 

 that the conditions were highly favorable to a similar orientation of 

 the crystals through the entire mass of the casting, except perhaps at 

 the lower end where solidification began. It seems likely that in the 

 long narrow tube, even if crystallization may originally begin about 

 several nuclei, that eventually one surface of advance of the crystal, 

 that on which growth is most rapid, will predominate over the others, 

 and that after this, crystallization will consist merely in a single sur- 

 face sweeping along the tube at a speed to keep pace with the lowering 

 of the tube. This presumption as to the uniformity of crystal struc- 

 ture throughout the casting should be verifiable by X-ray analysis, or 

 perhaps by a study of the etch figures; I have not yet made such an 

 analysis. In the case of zinc and tellurium, which were cast in the 



