1919 Gail; on Fiicits and Hi/drogen Ion 289 



of conductivity water and titrating with benzoic acid 99.90% pure fused, 

 Bureau of Standards. All other solutions, including the buffers, were 

 made according to the methods of Clark and Lubs (1917). These solu- 

 tions were also kept in paraffined bottles or resistance glass. 



The conductivity water was prejsared by the distillation of barium 

 hydroxide (Ba (0H)2) sat. sol. lOOcc, barium chloride (BaCU) sat. sol. 

 75 cc, alkaline potassium permanganate sol.* 50 cc, and enough distilled 

 water to make 2 liters. The first and last 600 cc of distillate were dis- 

 carded. The conductivity water and buffers were tested with the calomel 

 cell. 



The indicators used were plienolsulphonphthalein and o-cresolsulphon- 

 phthalein. A hydrogen set put up by Hynson, Westcott and Dunning of 

 Baltimore was also used, and proved very helpful as a check. 



pH Determinations 



Tests were made on alternate days for the hydrogen ion concentra- 

 tion during the last half of June, thru the entire month of July, and thru 

 the greater part of August. They were made in the following locations: 



I. Places where Fucus was abundant. 



1. Sunny exposure on Brown Island. 



2. Southeast half of Turn Rock. 



3. Southeast exposure on San Juan Island opposite Madrona 

 Point. 



4. On beaches having good rock for attachment of Fucus, much 

 light and little or no Ulva. 



II. Places where little or no Fucus grew. 



5. On beaches having good attachment, good light and an abun- 

 dant growth of Ulva. 



6. In tide-pools containing no Fucus but with an abundant growth 

 of it about them. 



7. Out in the Sound away from visible vegetation. 



8. On beaches having poor attachment for Fucus, much light 

 and little or no Ulva. 



9. Locations having little or no direct sun light. 



* NaOH 200g., KMnO, 8k., distilled in H^^O made up to 1000 cc. 



