Prof. J. W. Mallet on the Density of Solid Mercury, 149 



Applying the correction for capacity of vessel at the respective 

 temperatures, the three results were : — 



cub. centiins, grins. 



bQ-m2b of alcohol at -37° C. =50-7010 

 59-6600 „ „ -40° =50-8316* 

 59-6576 „ „ -42°-5 =50-9092 

 or, reducing to one common weight, 



cub. centims. grms. 



117-6752 of alcohol at -37° =100 

 117-3679 „ „ -40° =100 

 117-1843 „ „ -42°-5 =100 



(10) Taking the difference between (a) the first and second, (6) 

 the second and third, and (c) the first and third of these numbers, 

 and di\iding each difference by the number of degrees in the 

 interval of temperature, we get as the change of volume of 100 

 grammes of alcohol for 1° 0. : — 



cub. centim. 



From (a) -1024 



(5) -0734 



(c) -0893 



and the mean of these (-0884) may be taken to represent the co- 

 efficient for 1° C. within a range of a few degrees either side of the 

 freezing-point of mercury. IJsing this coefficient to reduce the 

 three weighings to their corresponding values for the same tempera- 

 ture, say — 39° C, we have 



grms. cub. centims. 



100 of the alcohol in question at -39° =117-4984 



„ „ „ „ „ =117-4563 



,, ,, „ ,, ,, =il7'4Jo7 



the mean of which is 117*4828 cub. centims. 



(11) The specific-gravity flask having been emptied and dried, 

 558-9353 grammes of mercury was introduced, the metal having just 

 previously been purified by careful treatment with dilute nitric acid, 

 washing with water, and quiet distillation from a glass retort. 

 Filling up with the same alcohol as that used in the above ex- 

 periments, and which had been kept in a well-stoppered bottle, the 

 flask was gradually cooled, and finally, in the last freezing-mixture, 

 the mercury frozen, and the alcohol brought exactly to the mark, 

 taking care that it became and remained quite stationary, while 

 dth?ing the freezing of the mercury the change of volume was very 

 r^id and easily observable. The temperature having been noted 

 when the final adjustment v\^as made, the little flask was set aside, 

 stoppered, until it could be washed off and dried, and was then 

 allowed to acquire the temperature of the balance-case, and weighed. 



temperature before introduction into the final freezing-mixture, and a separate 

 small portion in a tube was similarly cooled, to be used in filling up to the 

 mark if necessary. The stopper was carefully inserted as soon as the adjust- 

 ment of the liquid was secured, so as to avoid any loss by evaporation. 



* This weighing was not quite so satisfactory as the remainder ; the tempe- 

 rature a little doubtful. 



