The Hydrogen-ion Concentration, etc., of Sea-Water. 



65 



the outside temperature fell to about —30° C. The experhnents at 

 20° caused little worry in regard to temperature regulation, except on 

 some days when the outside temperature rose to about 10°. Owing to 

 conduction through hollow-tile walls from rooms at about 22°, it was 

 sometimes necessary to leave the window open about an inch. Great 

 care had to be taken then to equalize the temperature in different parts 

 of the room. Several thermometers were compared with a standard 

 and distributed around the room, one or two being placed on every piece 

 of apparatus in order to detect any inequalities in temperature. 



Great care was taken to prevent temperature changes in the appa- 

 ratus. When necessary to handle it, this was done very gingerly, with 

 the tips of the fingers on the extreme ends. Clamps were devised for 

 holding the apparatus in the various necessary positions. During the 

 night the temperature was controlled within 2° of that in the day by 

 means of a thermostat connected with the steam-heat radiator. 



HISTORICAL NOTES. 



IONIZATION OF SEA-WATER. 



Sea-water is a very complex solution, and it is not possible to calcu- 

 late the concentrations of the different ions in it from the older analyses. 

 Since many of these ions affect the Pg and the CO2 content, it might 

 be worth while to consider some general facts about the ionization. The 

 simplest method of determining the ionization of a dilute solution of 

 known concentration is by measuring the freezing-point. The accom- 

 panying table shows the relation of freez- 

 ing-point lowering (A) to salinity (S) of 

 sea-water from the determinations by 

 H. J. Hansen (Krummel, i, 241). The 

 ratio of A to S is 0.05424 at S = 30 and 

 0.05492 at S = 40, which might be inter- 

 preted to indicate that ionization increases 

 as the concentration increases, but this is 

 only an apparent paradox. In reality, sea-water is a concentrated 

 solution, and it is generally true that the A and osmotic pressure of 

 concentrated solutions increase more rapidly than the concentration. 



Electric conductivity experiments show exactly the opposite relation. 

 Figure 23, plotted from the data of Ruppin (Kriimmel, i, 291), shows 

 that the conductivity increases less rapidly than the concentration, 

 and that this is almost equally true at various temperatures. Con- 

 ductivity data must be considered with some caution, however, since 

 viscosity influences conductivity. This is apparent in the change of 

 conductivity with temperature shown in figure 24. It will be noticed 

 that conductivity of sea-water increases very rapidly with temperature, 

 and almost in direct proportion to it. The conductivity is doubled by 

 a rise in temperature of 30°, and it is very improbable that ionization 



