134 On Ice and Brines 



from the Firth of Clyde containing 1-84 per cent, of chlorine, 

 ice forms at - i'9C. The following results are from means 

 of close-agreeing results : 



Freezing temperature -2*0 -1-5 - ro -0-5 



Per cent, chlorine ... 1*94 i'445 0-963 0-475 



Difference o'o6 0*055 0-037 0-025 



Sea-water resembles a chloride of sodium solution con- 

 taining the same percentage of chlorine, and the resemblance 

 is closer the greater the dilution. When the beaker was 

 removed from the freezing-bath, the temperature rose during 

 melting as it had fallen during freezing. In these experi- 

 ments, which had for their object the determination of the 

 temperature at which the crystals melted, as well as that at 

 which they began to form in the water, it was impossible to 

 remove a sample for analysis large enough to enable the 

 sulphuric acid to be determined in it. 



For this purpose a series of observations were made, 

 using quantities of 300 grammes of sea-water. Freezing was 

 continued usually until the temperature had fallen o'3 C. 

 below that at which crystals began to form. The mother- 

 liquor was then separated from the crystals by means of a 

 large pipette with fine orifice, before removing the beaker 

 from the freezing-bath. The magma of crystals was then 

 brought rapidly on a filter and drained by means of the jet 

 pump. The ice, thus drained, was then melted, and the three 

 fractions were analysed. In the following table (I) the results 

 of four experiments are given. In the one column ( W} will 

 be found the weight of the original water taken and of the 

 fractions into which it was split on freezing ; in the other (R) 

 will be found the ratio of SO 3 to Cl found by analysis, the 

 chlorine being set down as 100 ; thus, in (I) the percentage of 

 chlorine found in the crystals, melting at the lowest tempera- 

 ture, was 1-497, and that of the SO 3 , 0-174; the ratio (R} is 

 therefore 1 1 '62. 



It will be seen that the ratios (R) found for mother-liquor, 

 drainings, and ice agree with one another quite as closely 

 as those found in samples of pure sea-water from different 



