232 True Weight of a Cubic Inch of Distilled Water. [June 19,. 



might be ; an uncertainty of 0'2 F. making a difference in the 

 weight of the cubic inch of 0'003 grain. 



Weighings. The weighings were made in three sensitive balances, 

 by Borda's method ; the gravimeter being suspended in water to- 

 a fixed depth, by a platinum wire. The largest errors in sucli 

 weighings are those likely to arise from minute bubbles of air 

 carried down by the body which, is suspended in water ; and as it is 

 impracticable to keep the gravimeter in boiling water, such bubbles 

 must be looked for, and the gravimeter repeatedly re-immersed. 



The normal air adopted in these weighings is that at t = 62 F.,. 

 6 = 30 inches, containing four volumes of carbonic-anhydride in every 

 10,000 volumes of air ; and also containing two-thirds of the amount 

 of aqueous vapour contained in saturated air ; weighed at West- 

 minster, latitude 51 29' 53", at 1G feet above sea-level (g West- 

 minster = <745 1-00057704). A cubic inch, of such air weighs- 

 0-3077 grain. 



Results of the present Experiments. 



C. Mean height 9'002020 inches. 



diameter 9'004148 



Vc 572-803651 cubic inches. 



Weight in air 183676'066 grains. 



in vacua . . . 183797-198 



AC 1-27049 



S. Mean diameter 5'992439 inches. 



Y s 112-6694096 cubic inches. 



Weight in air 28410'307 grains. 



invacuo... 28440*779 



Q. Mean diameter 3'083991 inches. 



height .. 3-018485 



Weight in air 15426-95495 grains. 



,, in vacuo. . . 15429'55515 ,, 



AQ 2-265425 



V Q 23-04014 cubic inches. 



In normal air a cubic inch of distilled water, freed from air, at the 

 temperature of 62 F., was found to weigh 



C 252-267 grains. 



S 252-301 



Q 252-261 



By the experiments with the sphere, apparently greater accuracy 

 was obtained than with the cylinders, and in calculating the weight 

 of the cubic inch, a higher value has been assigned to S ; or 



