Note 20 — Chapter X · SODIUM CHLORIDE—BERTHOLLET'S LAWS—HYDROCHLORIC ACID

If the sp. gr. S2 be found directly by dividing the weight of a solution by the weight of water at the same temperature and in the same volume, then the true sp. gr. S referred to water at 4° is found by multiplying S2 by the sp. gr. of water at the temperature of observation.