306 E. B. Rosa — Determination of v, the Ratio of the 



Ball A. 



May 1. Weight in air 2903-83 g. Temperature 18°*9 ; Bar. 76 

 cm. Volume of ball 4339* cc. Correction for displaced air 

 is consequently +4*83 g. .*. Weight of ball in vacuo = 2908*66 g. 

 A second determination gave 2908*64 g. I therefore take for the 

 true weight in vacuo 2 908*65. The ball being lighter than water 

 a sinker was attached and the following weighings made : 



May 3. W'tin distilled water, ball and sinker, 210*62 g. at 17°*05 C. 

 " " " sinker alone, 1635*59 " at 17*10 C. 



difference, 1424*97 " 



1425 



Correction for cc. air displaced bv weights *21 " 



8*4 i J s 



1424*76 " 

 Weight of ball in vacuo, 2908*65 " 



Loss of weight in water at 17°*05 C. = 4333*41 " 



" " " 4°* " 4338*68 " = 



volume in cubic centimeters. Another determination gave 4338*87. 

 I take as a mean 4338*8, which makes the mean radius r A ' = 

 10*1180 cm. An error of 0*1 in the number 4338*8 would cause an 

 error of less than a thousandth of a millimeter in r A '. 



Ball B. 



May 1. Weight in air, 2321*40 g. 



Correction for displaced air, 3*20 " == 2324*60 g. in vacuo. 



May 3. W't in distilled water, ball and sinker, 208.96 g. at 16°*45 C. 

 " " " sinker alone, 807*86 g. " 16°*70 C. 



difference, 598*90 " 



Correction for air displaced by weights *09 " 



59S-81 " 

 Weight of ball in vacuo, 2324*60 " 



Loss of weight in water at 16°*45 C. = 2923*41 " 



" " " 4°* " 2926*65 " = 



volume in cubic centimeters; this gives r B ' = 8*8735. A second 

 determination gave a closely agreeing result. 



In these weighings the bodies were lifted completely out of 

 water, replaced and air bubbles carefully removed at least three 

 times in each weighing. The mean of the several values, 

 which differed in the centigrams, was each time taken. These 

 differences were usually due to slight changes in the tempera- 

 ture of the water, the balances being far more sensitive than 

 the thermometer. As, however, the temperature was read to 

 ^th of a degree several times during a weighing and the 



