On Ice and Brines 133 



communicated to the Royal Society of Edinburgh contains the 

 first portion of the results. It deals with the subject under 

 two heads, namely, (a) the temperature at which sea-water 

 and some other saline solutions freeze, and the chemical 

 constitution of the solid and the liquid into which they are 

 split by freezing ; and (b} the temperature at which pure ice 

 melts in sea-water and in a number of saline solutions of 

 different strengths. 



(a) The freezing experiments were limited to sea-water 

 and solutions of NaCl comparable with sea-water. 



Chloride of Sodium. Four solutions were used, and they 

 were intended to contain 3, 2'5, 2, and i'5 per cent. NaCl 

 respectively. Forty grammes of this solution, in a suitable 

 beaker, were immersed in a freezing mixture of such composi- 

 tion as to give a temperature from 2 to 2'5 C. below the 

 freezing temperature expected. The temperature at which 

 ice began to form (if necessary after adding a minute splinter 

 of ice) was noted, and the freezing was allowed to continue 

 with constant stirring till the temperature had fallen o'2 C. 

 A specimen of the mother-liquor was removed, and the 

 chlorine in it determined ; the chlorine in the original solution 

 had been determined before. The beaker was then removed 

 from the freezing-bath and the ice in it was allowed to melt. 

 The temperature in all cases rose during melting exactly as it 

 had fallen during freezing. In the following table are given 

 the means of the temperature at which ice began to form in 

 the original solution, and that of the liquid when the sample 

 of brine was taken, and the means of the chlorine found in 

 the original solution and in the brine sample : 



Mean freezing temperature -i-875C. - 1'63 - i'3O -o'975 

 Mean per cent. Cl ... r%7 i'6o 1-30 0-98 



It will be seen that, in the dilute solutions experimented 

 with, the percentage of chlorine expresses, in terms of the 

 Centigrade scale, the lowering of the freezing-point of the 

 solution. 



Sea- Water. Similar experiments were made with sea- 

 water of different degrees of concentration. In sea-water 



