Note 18 — Chapter X · SODIUM CHLORIDE—BERTHOLLET'S LAWS—HYDROCHLORIC ACID

If S_0 be the specific gravity of water, and S the specific gravity of a solution containing p p.c. of salt, then by mixing equal weights of water and the solution, we shall obtain a solution containing ½p of the salt, and if it be formed without contraction, then its specific gravity x will be determined by the equation 2 / x = 1 / S0 + 1 / S , because the volume is equal to the weight divided by the density. In reality, the specific gravity is always found to be greater than that calculated on the supposition of an absence of contraction.