,^70 i\/r. Kirwan's Remarks onfpecifc Gravities 



In this calculation I take no account of the difference arlfing 

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

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

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

 point; confequently 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. 



-Hence alfo 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 onlyj,! 2 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 wat?er at 32° to be equal 

 to that at 53°,6 ; but that this irregular expanfion ceafed at 36"6, 

 and, according to Mr. De Luc (who firfl dlfcovered it) at 43''. 



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

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

 ties of the fame folid taken at different temperatures will be 

 ditferent ; and, what appears more extraordinary, the fame folid 

 will appear fpecifically heavier in higher than in lower tempera- 

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

 than in lower temperatures, the folid will lofe lei's of Its weight 

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

 may remedy by Infpe^ting 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 fpeciiic 

 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 iofcs therein 1 3,^^33 grains, if the 



* fame 



