1895.] Decimetre of Water at its Maximum Density. 



153 



where 0*999201 is the specific gravity of water at 58'4° F. ; Y 58 . 4 is 

 the volume of C at the same temperature (according to formula IV) 

 and Y t the volume of C at t° F. 



Weight of 

 1 cubic inch 

 of air, in 

 grains. 



True weight 

 of C in 

 water, in 

 grains. 



Weight of 

 displaced 

 water at t, 

 jp t , in grains. 



Tempera- 

 ture in 

 degrees 

 Fahren- 

 neiu. 



Specific 

 gravity of 

 water at t. 



Weight of 

 displaced 

 water at 

 58-4° F. 3 



1*58-4. in 

 grains. 



1. 



2. 



3. 



4. 



5. 



6. 



1. 0-314 



39103 '82 



144721 -42 



56 -38 



999335 



144704-64* 



2. 305 



39084 -6:4 



144740 -62 



57 -61 



-999262 



144735 -13 



3. 0-303 



39119 -16 



144706 -08 



58 -u0 



0-999233 



144703 -46* 



4. 312 



39103 -84 



114721 '40 



58-10 



-999224 



144718 -90 



5. "313 



39085 -81 



144739-43 



58 -87 



-999162 



144743 04 



6. 0-312 



39135-84 



144689 -40 



61 -42 



-998895 



144733 ■ 66 



The considerable differences in the numbers of the last column 

 show that in most of the observations there were air bubbles, which 

 Mr. Chan e y (loc. cit., p. 347) especially mentions in the discussion of 

 the weighings. As the air bubbles diminish the weight of C in 

 water, that is to say apparently increase the weight of the water, one 

 must believe that only in two weighings (marked with an asterisk), 

 Nos. 1 and 3, no bubbles, or very few, were shown, and I therefore 

 take for the computation these two weighings only. According to 

 them, the mean weight of water at 58'4° F. is P 58 .4 = 144704*05 grains ; 

 but as the volume of C (according to IV) at this temperature 

 Y 58 . 4 = 572-744125, we have for the weight of a cubic incli of water 

 at 58-4° F. = 252 - 6504 grains. The specific gravity of water at this 

 temperature being equal to 0*999201, it follows that the weight, in 

 vacuo, of a cubic decimetre of water at its maximum density (4° C.) 

 is equal to 999*8414 grams. 



This result, being so close k> that (999*8495 grams) deduced from 

 the best observations of Kupffer, shows at once that the method 

 selected by us gives useful results. It is confirmed by determinations 

 made by Mr. Chaney by means of a brass sphere S, having a diameter 

 of about 6 inches. The volume of the same Y 62 at 62° F. = 112-669406 

 cubic inches, and according to formula III, 



V* = Y 62 [l + 0*00003018 (t— 62) 4-0*000000009 (t— 62) 2 ]. 



Five very closely accordant weighings of S in air gave a mean 

 weight of 28409*913 grains, at the mean temperature t = 59*21° F., 

 H = 30 27" ; therefore the weight of 1 cubic inch of air = 

 0*3123 grain, and the weight of S, in vacuo, = 28440*778 grains. 



VOL. LIX. M 



