VOL. LXXV.] PHILOSOPHICAL TRANSACTIONS. (JQ7 



freezing to the boiling point, water is dilated about T V of its bulk. ; and con - 

 sequently, if 1000 ounces at the freezing point be equal to one cubic foot, they 

 must be equal at the boiling point to one cubic foot and 66.46 cubic inches. 

 And if dilatations are proportional to the degrees of heat throughout the scale, 

 there must be an augmentation of 3.136 cubic inches per cubic foot, produced 

 by every 10 degrees of heat. Both these points remain therefore to be deter- 

 mined; first, at what temperature a cubic foot of water weighs exactly 1 000 

 ounces avoirdupois ; and 2dly, whether the dilatations produced by successive 

 degrees of heat are proportional to the degrees that produce them. This last 

 point has indeed been handled by others, but with different views ; and their 

 determinations are not easily applicable to the present question. 



To examine this matter experimentally, I ordered a hollow tinned iron cone 

 to be made, of 4 inches diameter in the base, -^ of an inch diameter in the 

 summit inside, and 10 inches perpendicular height, whose solid contents should 

 be 42.961 cubic inches ; but by a slight diminution of the diameter, and a pro- 

 tuberance arising from the soldering, I found it to contain, in the temperature 

 of 6l°, only 42.731 cubic inches, according to the estimation of 1000 ounces 

 to the cubic foot ; and having filled it by immersion in boiling water, and taking 

 it up at different degrees of heat, and weighed it when cold, I found its contents 

 as expressed in the following table ; the first column of which shows the degrees 

 of heat at which it was taken up ; the 2d, the weight of the water contained in 

 it ; the 3d, the diminution of weight occasioned by those degrees of heat ; the 

 4th, the sum of the diminutions of weight in the cubic foot by the preceding 

 degrees of heat ; the 5th the weight of a cubic inch of water in each of those 

 degrees of heat ; and the 6th, the augmentation of bulk in the cubic foot by 

 every 20° of heat. The horizontal lines, marked thus*, are added from the 

 experiments of Mr. Bladh, in the Memoirs of the Academy of Stockholm for 

 the year 1776, whose determinations, as far as they reached, agreed very nearly 

 with mine. The water used was common water well boiled and filtered. The 

 experiments were for the most part 3 times repeated, and the difference in each 

 trial amounted to a very few grains. 



VOL. XV. 4 U 



