6 
The preparation of the various metre test solutions was 
described, and to facilitate the same, the solubility of the 
salts used, and the specific gravity of their solutions had been 
determined anew, and the results tabulated. A peculiar 
gradation of test liquids was recommended for indirect esti- 
mations. 
A color-error unit analogous to the error of the meniscus 
in gas analysis was stated, and its corrective use explained. 
The author, while regarding the processes described as well 
adapted for chemical research, also believes them capable of 
imparting greater precision to several industrial operations, 
and affording a safe and ready test as to the value of many 
commercial products. 
The above inquiry was conducted in the laboratory of 
Dr. R. A. Smith. 
