CHAP. XI. SPECIFIC GRAVITY OF SOLUTIONS.
��Specific Gravity of Electrolytic Solutions. — ^When we dissolve a substance, e.g. cane sugar, in water, the specific gravity of the solution deviates more and more from 1 as the concentration increases. In the case of most electrolytes the specific gravity increases. When we examine the depend- ence of the specific gravity on the normality n, we find that it can be represented by a function of the form —
S =^ Sq + an + ai«*.
Thus, for sugar solutions at 17*5^ we find, if the density of water at 17*5° be taken as unit —
S^ = 1 4- 0-1328?i - 0-002?i^
The first part of the following table shows how exactly the specific gravity may be obtained from a formula of this type—
��^ Cane migAr.
�Normality.
�Specific gravity (obaerred).
�Ppedfic gravity (calculated).
�
�
��The numbers in the lower part of the table have been calculated from the simpler formula — -
8^1 + 0-1313/1,
which gives the specific gravities up to normal concentration (30 per cent.) sufficiently accurately for most purposes.
�� �
