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XYI. On the Expansion of Sea-water by Heat. By T. E. Thorpe, Ph.B., and A. W. 
Rucker, M.A. ( Fellow of Brasenose College, Oxford), Professors of Chemistry and 
Physics in the Yorkshire College of Science. Communicated by W. B. Carpenter, 
M.D., LED., F.B.S. 
Received November 12, 1875,— Read January 6, 1876. 
The extensive contributions which have recently been made to the physical history of 
the ocean have shown the desirability of exact knowledge of the relations of sea-water 
to heat. We have accordingly thought it worth while to make observations in order to 
determine the law of the thermal expansion of sea-water. 
Hitherto the most important attempt to solve this problem was made by the late 
Prof. Hubbard, of the United States National Observatory ; the results of his investi- 
gation are contained in Maury’s ‘Sailing Directions,’ 1858, vol. i. p. 237. 
Muncke, nearly 50 years ago, determined the expansion of an artificial sea-water at 
various temperatures between 0° and 100° C. ; but our confidence in the results as 
applicable to natural sea-water is affected by the circumstance that the solution was 
prepared from data furnished by the imperfect analyses of Vogel and Bouillon La- 
Grange. 
The observations of Despretz were confined to temperatures below 13°-27, as the 
main object of his inquiry was to determine the point of maximum density of sea- 
water. The subsequent investigations of Neumann and Rossetti were equally limited, 
as they were undertaken with the same view. 
In accordance with our instructions, Captain Campbell, of the Anchor Liner ‘ Europa,’ 
kindly obtained for us a number of samples of Atlantic-Ocean water at various periods 
during a voyage from New York to Glasgow. The particular sample selected for 
observation was collected in lat. 50° 48' N. and long. 31° 14' W. The temperature of 
the surface-water was 52°-5 F. In the remarks accompanying the specimen it is stated 
that “ the weather had been moderate and pleasant for some days previously, and up 
to the morning of collection ; since then have had a brisk S. gale with heavy cross sea.” 
Two series of experiments have been made with this sample. 
In the first series our method of observation was precisely the same as that already 
employed by one of us in determining the expansion of the liquid chlorides of phos- 
phorus*. It was essentially that already used by Kopp and Pierre ; i. e. the expansion 
was observed in thermometer-shaped vessels (so-called dilatometers) graduated and accu- 
* Proc. Roy. Soc. vol. xxiii. p. 364. 
3 L 
MDCCCLXXVI. 
