30 
Of course phenolphthalein could not be employed as 
an indicator in this case as it is attacked by carbonic 
acid. 
The values given by this method are what seem to be 
most probably correct from titrations with several 
different portions of the sea waters. The titrated 
solution was found to become alkaline again on 
standing for some time, hence the imperfect results 
of this method. 
(b..\—By Estimation or Excress or Actp (Tornoe’s 
method)* 
Whilst the former method seemed to give too high 
results, this method when phenolphthalein was em- 
ployed as indicator, seemed to err on the side of 
lowness, which was probably due to the carbonic acid 
not being completely driven off by boiling. 
100 cc. of sea water were boiled for about twenty 
minutes with excess of standard sulphuric acid (about 
z20): Most other workers so far as I have been able to 
find out seem usually to have employed hydrochloric 
instead of sulphuric acid, but this latter seemed to me 
to possess a great advantage over the former in that 
there is practically no liability of the acid itself being 
carried away in the steam. Even in very dilute solu- 
tion hydrochloric acid is always more susceptible to loss 
in this way on boiling than is sulphuric. Sulphuric 
acid may have the disadvantage of being dibasic and so 
forming two series of salts, whereby the excess of acid 
might not be a direct measure of the alkalinity owing 
to the formation in unknown proportions of acid and 
normal salts, but as the base with which the carbonic 
acid in sea water is almost all combined is lime, this 
danger seemed to be almost completely done away with. 
*Den Norske Nordhaus-Expedition, 1876-1878, Chemi. Christiania. 
