1874.] Mr. J. Y. Buchanan on Sea-water Ice. 431 



XIV. " Some Observations on Sea-water Ice." By J. Y. BUCHANAN, 



Chemist on Board H.M.S. ' Challenger/ Communicated 

 by Professor A. W. WILLIAMSON, For. Sec. R.S. Received 

 June 9, 1874. 



Many different opinions have been expressed as to the nature of ice 

 resulting from the freezing of sea-water, all agreeing, however, in one 

 point, that, when melted, the water is unfit to drink. During the 

 antarctic cruise of H.M.S. 'Challenger' I took an opportunity of exa- 

 mining some of the broken pack-ice, into which the ship made an 

 excursion on the morning of the 25th of February, and also some ice 

 which had formed over night in a bucket of sea-water left outside the 

 laboratory port. 



The piece of pack-ice which I examined was, in substance, clear, with 

 many air-bells, most of them rather irregularly shaped. Two portions 

 of this ice were allowed to melt at the temperature of the laboratory, 

 which ranged from 2 C. to 7 C. The melting thus took place very 

 slowly, and made it possible to examine the water fractionally. My 

 experiments consisted in determining the chlorine in the water by means 

 of tenth-normal nitrate-of -silver solution, and observing the temperature 

 of the ice when melting. 



A lump, which, when melted, was found to measure 625 cub. centinis., 

 was allowed to melt gradually in a porcelain dish. When about 100 

 cub. centims. had melted, 50 cub. centims. were taken for the determi- 

 nation of the chlorine ; they required 13*6 cub. centims. silver solution, 

 corresponding to 0-0483 gramme chlorine. When 560 cub. centims. 

 had melted, 50 cub. centims. were titrated, and required 1-6 cub. centirn. 

 silver solution, corresponding to 0*0057 gramme chlorine. The remainder 

 (65 cub. centims.) of the ice was then melted and 60 cub. centims. titrated ; 

 they required 0*39 cub. centim. silver solution, corresponding to 0*0014 

 gramme chlorine. We have then in the first 50 cub. centims. 0-0483 

 gramme chlorine, in the next 510 cub. centims. 0'0579 gramme, and 

 in the last 65 cub. centims. 0*0015 gramme. Hence the whole lump 

 (625 cub. centims.) contained 0*1077 gramme chlorine, or, on an average, 

 0*1723 gramme chlorine per litre. A qualitative analysis of the water 

 showed lime, magnesia, and sulphuric acid to be present. 



Another piece of the ice was pounded and allowed to melt in a beaker. 

 When about half was melted, the water was poured off and found to 

 measure 95 cub. centims. ; 75 cub. centims. were titrated with silver 

 solution, and required 1-9 cub. centim. The remainder, when melted, 

 measured 130 cub. centims., and required 0-9 cub. centim. silver solution. 

 Hence the first fraction of 95 cub. centims. contained 0*0085 gramme 

 chlorine, and the second of 130 cub. centims. 0*0032 gramme chlorine. 

 The whole quantity (225 cub. centims.) of ice therefore contained 0' 01 17 

 gramme chlorine, or, on an average, 0*0520 gramme per litre. 



