544 Dr. E. L. Moss. Observations on Arctic Sea-water and Ice. 



" Observations on Arctic Sea-water and Ice." By Staff Surgeon 

 Edward L. Moss, M.D., K.N., late of H.M.S. "Alert." 

 Communicated by Sir GeorgeNares, Captain, R.N., K.C.B., 

 F.R.S. Received May 3, 1878. Read May 23.* 



In order that observations on the specific gravity of sea- water 

 shonld be made in the Arctic Expedition of 1875, by the method 

 successfully used on board Her Majesty's ship " Challenger, "f Sir 

 George Nares, when he left that ship to take command of the expe- 

 dition, brought with him one of Mr. Buchanan's hydrometers. 



Professor Hartley superintended the construction of its graduated 

 weights, and suggested the supply of apparatus for the volumetric 

 estimation of chlorine ; and, on the departure of the expedition, both 

 sets of observations were allotted to me. 



Storms interfered with observations in the Atlantic, but they were 

 begun on entering Baffin's Sea, and continued till the ships finally 

 rounded Cape Farewell. Most of the samples of water examined 

 were from the surface, or from close beneath the floes ; but whenever 

 the exigencies of ice navigation permitted, samples were obtained from 

 various depths by means of " Buchanan's bottle." The " bottle " was 

 also used in winter quarters, at first through holes made in the new 

 ice, and afterwards of greater depths, when tidal fissures formed wide 

 enough to let it pass down between the heavy floes. In very cold 

 weather, or when surface fresh water lay over a salt stratum with a 

 temperature below the freezing point, it was found necessary to be 

 specially careful to prevent the addition or withdrawal of ice by the 

 cold brass of the bottle ; and during winter, water, however obtained, 

 had to be re-mixed after it had acquired the temperature of my cabin, 

 for ice formed in transit from the floes to the ship, melted, and lay in a 

 differently refracting layer on the surface. The temperatures were 

 ordinarily taken with an open scaled centigrade thermometer, verified 

 at its zero. Its readings were constantly checked by observations 

 with the Miller- C as ella and Negretti and Zambra instruments, by 

 which all the temperatures away from the surface were obtained. 



In the reduction of the specific gravities to a common temperature, 

 Hubbard's coefficients were at first used, but all the observations on 

 sea-water in the subjoined tables have been re-calculated by the 

 formulas published during the absence of the expedition by Professors 

 Thorpe and Riicker.J In the few instances in which the observations 

 were made at minus temperatures, the reductions have been arrived at 



* See ante, p. 446. 



f Mr. J. Y. Buchanan, " Proc. Roy. Soc," vol. xxiii, 1875, p. 301. 

 X " Trans. Eov. Soc," vol. clxi, Part II, p. 405. 



