MARINE BIOLOGICAL STATION AT PORT ERIN. 27 
and (3) lowering the pressure and continuous removal of 
the gaseous carbon-dioxide. The volume of gaseous 
carbon-dioxide can be measured and reduced to normal 
temperature and pressure (C. J. J. Fox), or the gas can be 
absorbed by barium hydrate. The method followed was 
the latter, and the precipitated barium carbonate was 
filtered off, washed, and titrated by standard acid in the 
presence of di-methyl-amino-azo-benzol. 
‘“The usual method used to determine the alkalinity 
is cumbersome, as one adds excess of acid, boils for half 
an hour, and titrates back by barium hydrate in the 
presence of phenol-phthalein. A much simpler method 
was used. The sea-water was titrated with N/10 
hydrochloric acid in the presence of di-methyl-amino-azo- 
benzol. The principle is to use an indicator that is not 
sensitive to such a weak acid as carbonic acid, and hence 
the excess of bases not combined with strong acids is 
determined. By using a control of sea-water containing 
the same amount of indicator and possibly by using a 
special burette and more dilute acid the delicacy of the 
reaction can be increased. 
““The advantages were a great saving of time, and 
the errors of two burette readings instead of four. The 
results showed the same alkalinity as was obtained by the 
longer method. 
‘Calcium was determined by precipitation, as 
oxalate, in the presence of acetic acid. The precipitate 
was dissolved in dilute hydrochloric acid and reprecipi- 
tated by sodium acetate. After washing the precipitate 
it was titrated by potassium permanganate in the 
presence of sulphuric acid. 
‘Under the head of Comparative Physiology, a 
number of points in connection with the physiology of 
digestion, respiration, etc., of invertebrates were 
