BRIDGMAN. — THERMODYNAMIC PROPERTIES OF WATER. 315 



was placed in the lower part of the hydrauHc press and, together with 

 the lower part of the press, was placed in the thermostat. Tlie di- 

 mensions were so small that this could he done without increasing 

 to an unwieldly l)ulk the size of the apparatus, the four tie rods of the 

 press being 1 1/S" in diameter and their centers 6" apart. It is the 

 same form of apparatus which was used for the measurements on ice 

 VI up to 20,500 kgm. The present experiments run to only 12,000 

 kgm., howe\er, since it is evidently an absolute essential to the success 

 of the method that there should be no permanent distortion of the 

 cylinder. It would be easily possible to reach pressures much higher 

 than those reached in this experiment, but it was felt that the risk 

 and the extra time involved in the probable construction of new 

 apparatus was not justified at present, when it seemed that the most 

 important work was to map out the field, obtain data for as many 

 liquids as possible, and determine the general nature of the significant 

 problems. Later, if there are crucial points which need the use of 

 much higher pressures, it will be a comparatively easy matter to obtain 

 them. 



The cylinder used in this experiment was not the same as that used 

 in the previous work on water. This new cylinder is from a piece of 

 chrome-vanadium steel made in the electric furnace by the Halcomb 

 Steel Co., of Syracuse, N. Y. The steel itself is a wonderful product, 

 and without it the present investigation would not have been so easily 

 possible. It shows a tensile strength of 300,000 lbs. per sq. in. when 

 hardened in oil, and an elastic limit of about 250,000 lbs. These 

 figures are considerably in excess of those for the steel used in the 

 previous investigation. The steel furthermore is remarkably homo- 

 geneous, because of its production in the electrical furnace. One of 

 these pieces was pierced with a hole 1/8" diameter and 13" long, and 

 the drill came through concentrically without any variation from the 

 straight line. The dimensions of the cylinder used in the present 

 work were 4 1/2" outside diameter, 13" long, inside diameter 17/32" 

 for the greater part of its length, with an enlargement to 3/4" at the 

 lower end for the reception of the manganin coil. The original inside 

 diameter was 7/ 16". The cylinder was prepared for use by hardening 

 in oil and then subjecting to a pressure much in excess of that con- 

 templated for the actual experiment. The seasoning pressure was 

 over 30,000 kgm. Even under this high seasoning pressure the 

 cylinder showed very little permanent change of internal dimensions, 

 not stretching as much as 1/32." This is less than the amount of 

 stretch which has been found for any other grade of steel. The 



