218 CARNEGIE INSTITUTION OF WASHINGTON. 



precipitation of CaCOs. This point varies according to the condition of the 

 sea-water. For example : 



A. 100 c.c. sea-water + lOdropsof phenolphthalem+ 1 c.c. N /IOOH2SO44-I c.c. N /lOONaOH. 



B. 100 c.c. 8ea-water+ 10 drops phenolphthalein. 



Tube A is pinker than tube B, thus showing that A contains less free acid 

 than does B. A definite amount of N/100 NaOH must be added to B to cause 

 its color to match that of tube A. This amount varies with the amount of 

 N/100 H2SO4 added, but reaches a maximum at the point where enough 

 N/100 H2SO4 has been added to neutralize the normal carbonate (titrated in 

 the cold with phenolphthalein) . The less alkaline the sea-water is at Tortugas, 

 the more aciditv it will lose after exactly equal amounts of N/ 100 H2SO4 are 

 added, followed^by N/100 NaOH. 



A. 100 c.c. sea-water+10 drops phenolphthalein +2 c.c. N/100 H2SO4+2 c.c. N/100 



NaOH Decided pink. 



B. 100 c.c. sea-water+10 drops phenolphthalein +2 c.c. N/100 NaOH + 2 c.c. N/100 



H2SO4 Faint pink. 



The amount of N/100 NaOH which must be added to B to make its color 

 match that of A is a function, as stated before, of the original amount of N/100 

 H2SO4 added, also of the amount of sea-water used. At Woods Hole, in a 

 certain sample of sea-water, 2.5 c.c. N/100 H2SO4 will completely decolorize 

 the pink color of 100 c.c. sea-water. The maximum loss of acidity in this sea- 

 water was 0.3 c.c. of N/100 H2SO4 for 100 c.c. of sea-water. For example, 

 if there is added in sequence (Woods Hole water) : 

 (a) A. 250c. c. sea-water + 10 drops of phenolphthalein + 6 c.c. N/100 H2SO4+6 c.c. N/100 



NaOH Decided pink. 



B. 250 c.c. sea-water+ 10 drops of phenolphthalein + 6 c.c. N /lOO NaOH + 6 c.c. N /lOO 



H2SO4 Faint pink. 



It was necessary to add 7 to 8 c.c. of N/100 NaOH to B to cause it to assume 

 the same intensity of color as that of A. 

 (6) A. 100 c.c. sea-water + 10 drops of phenolphthalein + 6 c.c. N /lOO H2SO4 + 6 c.c. N /lOO 



NaOH Decided pink. 



B. 100 c.c. sea-water + lOdrops of phenolphthalein + 6 c.c.N/100 NaOH + 6 c.c. N/lOO 

 H2SO4 Faint pink. 



To B we had to add 0.3 c.c. of N/100 NaOH to cause it to become as dark 

 in color as A. 



These experiments show there is in sea-water a certain amount of some 

 form of CO2 which becomes lost when an acid is added, and this amount is a 

 function of the amount of sea-water used, and not of the amount of acid added. 

 Thus, in these experiments the maximum loss of acidity is represented by 

 2.5 c.c. of N/100 H2SO4 for each 100 c.c. of sea-water. This amount is from 

 6.6X10"'' gram to 9X10"'' gram of CO2 per c.c. of sea-water, which is a 

 little above that contained in air at the present time. 



I can not assert that this CO2 contained in sea-water is "free," but the fol- 

 lowing experiments are extremely suggestive: 



(a) Sea-water at Tortugas loses CO2 continuously. 



(6) If one precipitate CaCOa from sea-water by adding an excess of NaOH so that theCaCOs 

 coats the sides of the bottle, and if one then wash the bottle several times 

 with sea-water carefully and shake constantly, thus freeing all NaOH from 

 the bottle, but leaving a certain amount of precipitated CaCOs adherent to 

 the sides of the bottle, and then fill the bottle with fresh sea-water; if one 

 compare this sea-water with natural sea-water after both have been standing 

 24 hours, it is found that the sea-water in the bottle which contains the pre- 

 cipitated CaCOa is less acid than natural sea-water. Also, the loss of acidity 

 corresponds nearly to 6.6 to 9 X 10~^ grams of CO2 per cubic centimeter of sea- 

 water or about to that stated above. 



