398 K. J. ALLEN AND E. W. NELSON. 



Then if A is the alkalinity of the standard andX the required 

 alkalinity of sample: 



Nd 



Since all operations were carried out at the same room 

 temperature, no corrections for temperature are necessary. 



In spite of the greatest care consistent results could not be 

 obtained by this method of analysis. A sample analysed 

 against the same standard would sometimes give results 

 vai-ying as much as 0'5 mgrm. and occasionally 1*0 mgrm. 

 OH °/qq. 'J'he work on indicatoi-s by Salm (42) and its 

 application to this question has only recently come to our 

 notice, and it is our intention to experiment on this in future 

 research. 'J'he figures quoted below as the results of analyses 

 have been rounded off as whole nujnbers, since their interest 

 lies in their comparative rather than their absolute value. 

 For convenience they are quoted as " alkalinities," although 

 we are fully conscious that the methods used do not warrant 

 this assumption, and that their actual chemical significance 

 is still obscure. 



The mean value for " outside water " was found to be 

 fairly constant at 40'0 mgrm. OH ^/qq, which figure agrees 

 with results obtained by others for average ocean water. 

 Samples from the aquarium tanks never gave as high figures 

 as this, the average being approximately 37"5 mgrm. OH °/^^. 

 From this it seems that the amount of base in equilibrium 

 with COo in tnnk-water is appreciably less than in outside 

 water. A series of thirteen samples taken from seven miles 

 beyond the Eddystone to well inside the Cattewater (an 

 inner tidal harbour near Plymouth) showed a gradual lowering 

 of the alkalinity from the normal 40, to 38 mgms. OH °!^ as 

 the water became more estuarine and polluted. 



The addition of Miquel's solution B to sea-water was found, 

 on analysis, to reduce the "alkalinity'^ by an amount equiva- 

 lent to 10 mgrm. OH °/^^ or more. The 1 c.c. solution 

 B added to a litre of sea-water in itself contains a certain 

 amount of free acid, equivalent to less than 4 mgrm. OH °/ 



'oo* 



