Introduction to the study of inorganic chemistry / by William Allen Miller.

  • Miller, William Allen, 1817-1870.
Date:
1871
Catalogue details

Licence: Public Domain Mark

Credit: Introduction to the study of inorganic chemistry / by William Allen Miller. Source: Wellcome Collection.

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    Saturation—Crystallisation. 5S Sea 7oater is largely loaded with common salt, and with 1 magnesic chloride and sulphate, to which last the bitter taste ' is due. It contains also a large number of other salts; ■ among these are small proportions of bromides and iodides. A litre of sea water contains about 37 5 grams of various salts dissolved in it; about 29 grams of these consist of : sodic chloride. \Vater dissolves certain bodies, such as common salt, nitre, and Epsom salt, with great ease; but other salts, such as calcic sulphate, are soluble in mucli smaller’ j>ro- portion in the same quantity of water. ^Vhen water has dissolved as large a proportion of any substance as it can take up, it is said to l)e saturated with that substance. Some substances, .such as silver chloride and siliceous ; sand, are not soluble in water to any sensible extent. ' Generally speaking, water, though .saturated with any jrarti- cular salt when cold, will dissolve a larger quantity of the same salt when heated. Exp. 41.—Grind up in a mortar 50 or 60 grams of sodic sul- phatc,with about twice its weight of water at 15° C. The water will dissolve a considerable proportion, but not the whole of the salt. Pour this saturated solution into a flask, and warm it gently; it will now dissolve 50 grams more of the salt without difficulty. Allow the solution to cool down to the temperature of the air, say 15° C. : long four-sided needles will crystallise from the liquid. Pour off the liquid, and dry the crystals by pressing them between a few folds of blotting-paper. When they appear to be dry, put a small quantity of the crystals into a test-tube, and apply a gentle heat : the salt will liquefy, and on continuing to apply the heat a large quantity of water will be driven off, and a dry white powder will be left in the tube. Tlie water thu.s given off was chemically combined with the crystals. Many other salts which appear to be ])erfectly dry to the touch, give olT water when heated, and crumble down to a shapeless mass ; such, for e.\am])le, as alum, cupric suli)hate, and sodic carbonate; but they all lose the dis-