26 



PROCEEDINGS OP THE AMERICAN ACADEMY. 



Below is given a partial table of this sort, which suffices for ordinary 

 work with crystallized salts. It was obtained from the data above men- 

 tioned by graphic interpolation. The specific gravities of diluted sul- 

 phuric acid given in the last three columns are taken at 15°, and referred 

 to water at 4°; — sulphuric acid of any strength given below placed in 

 a desiccator kept at the temperature given at the top of the column, is 

 then capable of yielding aqueous vapor at a tension found in the first 

 column. Since the curves corresponding to Regnault's data are not quite 

 regular, these values are only near approximations. 



Specific Gravities of Sulphuric Acid capable of yielding Aqueous 



Vapor at various Tensions. 



This table is also of practical use in preparing dry crystallized sub- 

 staiices. For instance, crystallized oxalic acid, so much used in making 

 standard solutions, is best prepared by placing tiie powder over sulphuric 

 acid of specific gravities 1.20 to 1.50; for the crystallized substance 



