152 Prof. D. Mendeleeff. On the Weight of a Cubic [Dec. 5, 



9 inches diameter and height) the cylinder C was distinguished, the 

 volume of which at 62° F. = Y 62 = 572-80365 cubic inches. The 

 cylinder was made of gun-metal, and we have for the same, according 

 to Fizeau's determinations : — 



v t = v Q (1 + 0-00005106 t + 0-00000003 f), 



where t is expressed in degrees Celsius ; or, if we start from V 62 and 

 use the Fahrenheit scale, we have : — 



V t = V 62 [1+0-00002890 (t— 62) +0*000000009 (t— 62) 2 ]. . . 6 (IV) 



The weighings in air gave : — 



Weight in air Temperature 



in grains. of air. Barometer at o°. 



183676-336 57'5° F. 29-98" 



•259 57*3 29-98 



•248 60-1 30-22 



•302 58-2 29-34 



Mean. 183676*286 58-27° F. 29*88" 



The specific gravity of the weights was 8*0298. Assuming the 

 humidity = 66*7 per cent., we have for the weight of a litre of air 

 1*2216 gram, or the weight of a cubic inch 0*3089 grain, and there- 

 fore the weight of C, in vacuo, P = 183825*243 grains. 



Six weighings in water, arranged according to the temperature of 

 the water, gave : — 







Apparent weight 









Temperature 



of C in water, 



Temperature 



Barometer 





of water. 



in grains. 



of the air. 



at0°. 



1. 



56*38° F. 



39109*87 



56-5° F. 



30*22" 



2. 



57*61 



39090-50 



56*8 



29*38 



3. 



58-00 



39125-00 



58-2 



29*34 



4. 



58-10 



39109-85 



57-2 



30T5 



5. 



58-87 



39091-84 



56*0 



30*14 



6. 



61*42 



38141-86 



59*5 



30-30 



In order to find the weight of the displaced water, first the weight 

 of a cubic inch of air was calculated (column 1), and by this means 

 the true weight of C in water (column 2). After this by subtracting 

 from P the weights p t of the displaced water (column 3) at the tem- 

 peratures t° F. (column 4), from these data, knowing the specific 

 gravity of the water (column 5), the weight P of the water at the 

 mean temperature 58*4° F. was calculated, using the formula : — 



^ Vt . 0-999201 V«j 



