Methyl- 

 Violet, 



Tropaolin 00 



Butter yellow 



Methyl orange, .02% 

 4Br phenolsulfophthalein 



Methyl red, .04% 

 p nitrophenol, .5% 

 Neutral red, .02% 



Phenolsulphonepthalein, .05% 

 6 P H 7 



-15', 

 a napthol phthalein 



Thymolsulfophthalein, .05% 



.03% 



.03% 



8 9 10 



2 Br -thymolsulfophthalein, .05% 



a naptholsulfophthalein 



Phenolphthalein, .2% 



Thymolphthalein, .05%, 





FIG. 3. Conversion table for roughly determining the P H of any aqueous solution. The solution is 

 placed in a test-tube of 1 cm. bore together with 0.1 c.c. of tin- indicator solution of the indicated 

 concentration and the color is compared with the chart while looking downward into the lube. 

 In many cases two attempts to match the color were made, the continuous scale beinsr made with 

 the aid of water colors and the discontinuous M-ale with the aid of aniline dyes. About 0.3 must be 

 subtracted from the P H of sea-water as determined by this chart if sulfophthalein indicators are 

 used, to correct for the salt error. For finer work the tubes described in this paper are recommended. 



