1890.] 



Observations on Pure Ice. 



109 



perature was also regularly taken ; the latter corresponded with the 

 temperature of the ice. The results are given on Diagram II. In 

 connexion with the influence of the composition of water on the 

 plasticity of the ice frozen therefrom, it may be desirable to give an 

 analysis of the water supplying the pond, which was as under: 



Table I. Analyses of Water. 

 Results in Grains per Gallon. 



Total 

 residue. 



Inorganic 

 matter. 



Loss on 

 ignition. 



Total sulphates 

 as (S0 3 ). 



Dry seasons. . . 

 Rainy seasons . 



15-68 

 11-31 



11-70 

 7-56 



3-58 

 3-75 



3-29 

 2-93 



Analysis of sample of water, during a very dry season. 

 Results in grains per gallon. 



Deposit on boiling '30 



Iron (Fe) - '28 



Calcium (Ca) 3'29 



Magnesium (Mg) 1 '44 



Chlorine (Cl) 0'69 



(SO 4 ) 2-88 = SO 3 2-4 



8-88 



Total inorganic matters ... 8 '40 



The above analyses of the water during dry seasons are the average 

 of nine different analyses at periods extending over six years, and the 

 analyses of the water during rainy seasons are the average of ten 

 analyses at various periods during six years. 



The reaction of the water with litmus was slightly acid, and sul- 

 phates were generally present in quantity. 



A number of experiments were made to ascertain whether any por- 

 tion of the saline constituents of the pond water was taken up into 

 the ice during crystallisation. Contrary to expectation, and instead 

 of the ice being found perfectly pure and free from saline matters, it 

 was noticed that the composition of the natural ice was materially 

 affected by the presence of a proportion of the salts of the water from 

 which the ice was crystallised. Roughly speaking, the proportion of 

 inorganic matter found in the melted ice would be about 10 per cent, 

 of the total inorganic salts contained in the pond water from which 

 it was frozen; it was also observed that there was a great proper- 



