TEMPERATURE OF WATER i8i 



(Regnard-28:4jy.) A direct passage of organisms from the fresh 

 waters to the sea or the reverse is thus attended with great dangers 

 to the organisms, and can be safely accompHshed only through the 

 intracontinental waters of intermediate salinity. 



TEMPERATURE OF THE HYDROSPHERE. 



Freezing Point of Water. 



The freezing point of pure water is o° C. or 32° F. With addition 

 of salts the freezing point is lowered as shown in the following 

 table, condensed from Kriimmel (20:247). 



Salinity I permille, freezing point — o . 055° C. 



Salinity 5 permille, freezing point — o. 267° C. 



Salinity 10 permille, freezing point — o . 534° C. 



Salinity 15 permille, freezing point —0.802° C. 



Salinity 20 permille, freezing point — i . 074° C. 



Salinity 25 permille, freezing point — i . 349° C. 



Salinity 30 permille, freezing point — i .627° C. 



Salinity 35 permille, freezing point — i .910° C. 



Salinity 40 permille, freezing point — 2 . 196° C. 



Ordinary sea water of 35 permille salinity will therefore freeze at 

 a temperature of — 1.9° C. or +28.58° F. when its density (o-t) is 

 28.21. According to the formula given by Kriimmel, the surface 

 water of the Black Sea, with a salinity of 18.5 permille, will freeze 

 at a temperature of — 0.99° C. ( + 30.2° F.), that of Behring Sea 

 (30 pennille) at — 1.6° C. ( + 29.12° F.), while the water of the Baltic 

 (7.8 pennille) would freeze at about — 0.4° C. ( + 31.28° F.) If o-q 

 is known (see formula p. 180) then the freezing point t of water may 

 be calculated according to the following empirical fonnula devised 

 by H. J. Hansen of Copenhagen (Krummel-2o:i'^o). 



T = — 0.0086 — 0.064633 o-Q — 0.0001055 ""o^-* 

 According to this fomiula the waters of the Karabugas Gulf where 

 (To = 353.329 would freeze at a temperature of — 36.016° C or 

 — 32.836° F. if it were of the composition of normal sea water. 



Heat Capacity or Water. 



The heat required to raise a gram of pure water from 14.5° to 

 15.5° C. is the unit of measurement of the heat capacity or specific 

 heat of water, and is called the small calorie or gram-calorie. Saline 

 waters have a smaller heat capacity than pure water, i. e., it takes 

 less heat to raise a gram one degree. The following table is given 



* The formula as printed in Kriimmel is incorrect, the second term of the 

 right-hand member is there given as o.oo64633(ro. 



