256 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



November 17th, 1912. Took three samples of water 

 (A) from Pond I. (large spawning pond), (B) from Pond II. 

 (smaller pond at West end beyond sluice), (C) from open sea 

 at Breakwater. A sample of 100 c.c. in each case was titrated 

 with centi-normal hydrochloric acid, with phenol-phthalein as 

 indicator (4 drops of 0-5 per cent, phenol-phthalein in the 

 100 c.c.) with the following results : — 



(A) Pond I. Required 1-9 c.c. 



(B) Pond II „ 1-9 c.c. 



(C) Breakwater „ 0-9 c.c. 



Thus, the water from the two ponds was approaching the 

 spring alkalinity while the Bay water was at winter level. 



The ponds were shortly afterwards emptied, the walls 

 disinfected and algae removed as far as possible, and then 

 refilled. Examined again in February, 1913, the alkalinity 

 was found to be the same as that of the " Bay " water. 

 Samples of " Pond " water and of " Bay " water taken then 

 and titrated alongside each other as before, gave in each case 

 an alkalinity represented by 1-3 c.c. of centi-normal acid. 



It hence became obvious that the increased alkalinity was 

 caused by the algal growth causing photo-synthesis and the 

 conversion of bi-carbonate into alkaline normal carbonate. 



The same effect was demonstrated in the determination 

 of the hydrogen-ion concentrations in the " Pond " and " Bay " 

 waters by Sorensen's method. At this earlier period the sea- 

 waters were contrasted with mixtures of the two phosphatic 

 solutions, because the alkalinity was not expected to run so 

 high. The two pond-waters in November, 1912, matched at 

 9-8 c.c. of alkaline phosphate to 0-2 c.c. of acid phosphate, 

 while the " Bay " water matched it at 9-7 c.c. alkaline phos- 

 phate to 0-3 c.c. of acid phosphate. After correction for salt 

 effect these values correspond to P H> 10" 83 for the " Pond " 

 water and P H) 10 ~ 8 - 1 for the " Bay " water, 



