6g& 



PHILOSOPHICAL TRANSACTIONS. 



[anno 1785. 



Hence we see, that a cubic foot of water weighs 485.3 grains more at 42° 

 than at 62°, and consequently is equal to 1001.109 avoirdupois ounces, and in 

 the temperature of 82° it weighs less than at 62° by 788.5 grains, and therefore 

 is equal to 998.198 ounces. At the boiling point it wants 16089 grains, or 

 37.915 ounces of the weight it possesses at 62°, and consequently weighs only 

 962 .08 5 ounces, Sec. Hence also we see, that the expansions of water are not 

 proportional to the degrees of heat ; for by 20 degrees of heat from 62 to 82° 

 a cubic foot of water is dilated only 3.12 inches, but by the next 20 degrees of 

 heat, that is, from 82° to 102°, it is expanded 5.7 inches, &c. Mr. Bladh 

 found the volume of water at 32° to be equal to that at 53°.(3 ; but that this 

 irregular expansion ceased at 36°.6, and according to Mr. De Luc (who first 

 discovered it) at 43°. 



As the expansion of liquids by equal degrees of heat is much greater than that 

 of solids, it happens, that the specific gravities of the same solid taken at dif- 

 ferent temperatures will be different ; and, what appears more extraordinary, the 

 same solid will appear specifically heavier in higher than in lower temperatures ; 

 for the same volume of water being lighter in higher than in lower temperatures, 

 the solid will lose less of its weight in it in the former than in the latter case : 

 this mistake we may remedy by inspecting the 5th column of the foregoing table 

 and the following analogy : as the weight of a cubic inch of water at the 

 temperature of 62 , is to the weight of a cubic inch of water at n degrees 

 of temperature, so is the specific gravity found at n degrees of temperature, to 

 that which will be found at 62°. Thus, if 1000 grains of iron be weighed in 



