2 70 Mr. Kir WAN's Reworks onfpec'ific Gravities 



' In this calcuiatiou I take no account of the difference arlfing 

 from the expanfion of the veffel, It being only 0,067 of an 

 hich at the boiling point; for, according to Bouguer, iron is 

 dilated 0,00055 of its bulk from the freezing to the boiling 

 point; confequentlj 42,961 cubic inches gain only 0,067 ^^ '^^ 

 inch, augmenting the diameter and perpendicular height of 

 this fruftum of a -cone at the boiling point in that proportion. 



ilcnce alio we fee, that the expanfions of water are not pro^ 

 portional to the degrees of heat ; for by 20 degrees of heat from 

 62'' to 82" a cubic foot of water is dilated only^,! 2 inches, but by 

 the next 20 degrees of heat, that is, from 82° to 102°, it is 

 expanded ^^'] inches, &c. 



Mr. Bladh found the volume of wat?er at 32° to be equal 

 to that at ^'^^(y ; but that this irregular expanfion ceafed at 36-6, 

 and, according to Mr. De Luc (who firft difcovered it) at 43°. 



As the expanfion of liquids by equal degrees of heat is much 

 greater than that of foiids, it happens, that the fpecific gravi- 

 ties of the fame folid taken at different temperatures will be 

 different ; and., what appears more extraordinary, the fame folid 

 will appear fpecitically heavier in higher than in lower tempera- 

 tures ; for the fame volume of water being lighter in higher 

 than ill lower temperatures, the folid will lofe lefs of its weight 

 in it in the former than in the latter cafe : this mlilake we 

 may remedy by infpe6llng the fifth 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, fo is the fpecific 

 gravity found at n degrees of temperature to that which will 

 be found at 62°. 



Thus, if 1000 grains of iron be weighed in water of the 

 •temperature of 62°, and it lofes therein i 3,^33 grains, if the 



fame 



