i6 , SCHMITZ, On a Method of Ice Calorimetry. 



a sphere or other well-rounded object, there is generally 

 only a single passage, a hole of about a millimetre in 

 diameter near the place of attachment of the thread. 

 Through this hole a number of bubbles escape during the 

 first two or three minutes after immersion, and these are 

 followed at longer and longer intervals by a few other 

 bubbles. In the present experiment, probably about 

 five bubbles escaped during the first two minutes, and 

 during the remainder of an hour two additional bubbles. 

 The first weighing was made about two minutes after 

 immersion. The interpretation of the weighings was as 

 follows : (i.) Nine-tenths of the ice was formed during 

 the first two minutes, and practically the whole of the ice 

 during the first three minutes, (ii.) A bubble of volume 

 •06 c.c. escaped about five minutes after the moment 

 of immersion, and a second bubble of the same volume 

 about twenty minutes after the moment of immersion, 

 (iii.) The ice-jacket was melting at the rate of about 

 3 per cent, per hour.* 



The increase in the numbers of p. 15 is therefore not 

 due to an increase in the mass of ice. The explanation 

 seems to lie in the gradual escape of air from the ice- 

 jacket and the replacement of this air by water leaking 

 into the interior of the ice-jacket.f 



The total mass of ice formed round the copper sphere 

 was about 12 grammes. An addition of "12 grammes of 

 water exactly replacing the two bubbles of air would 

 produce an error of one per cent, for an immersion of 



* The ice-tray was not used in this experiment. 



t It may be of interest to add that the small-air cavity in the case ot 

 the sphere was always formed at the top of the sphere. On the other hand, 

 in the case of the flat-ended cylinder of p. 15, a large air-bubble, separated 

 from the water below it by a thin film of ice, appeared at the base of the 

 cylinder immediately after immersion ; the size of this bubble gradually 

 became less while its ice-skin increased in thickness ; the final result at the 

 base of the cylinder was in some experiments a thin film of firm ice practi- 

 cally in contact with the metal, in others a spongy mass of ice. 



