820 



BULLETIN OF THE BUREAU OP FISHERIES 



correction of — 0.01 of pH, and a correction of + 0.01 for every 1 per mille by which 

 the salinity falls below 32 per mille, thus: 



Salinity, per mille Correction to pH 



29 +0.03 



30 +0.02 



31 +0.01 



32-33 



34 -0.01 



35 -0.02 



For use on shipboard, where conditions of light and shade are not always of the 

 best, and where the lurching of the vessel may make it difficult to handle delicate 

 apparatus, a dark comparator box, in which three tubes can be inserted — the sea 

 water to be tested and a standard on either side of it — much facilitates the comparison 

 of slight differences of color. We have made the following series of determinations 

 from the Albatross and Halcyon. Accuracy can be expected to ±0.05 of pH, my 

 experience corroborating Mayor's (1922, p. 65) statement that differences as small 

 as 0.03 pH can be detected with the particular colorimetric tubes employed. 



Albatross stations 



