A Practical Manual On Sea Water Distillation
With A Description Of The Necessary Machinery For The Process

TYPES OF DISTILLING APPARATUS. 13 the result that an insoluble white precipitate is at once formed, varying in quantity according to the amount of chlorine (that is, chloride of sodium) present. The other salts found in sea water are mostly salts of calcium (lime) and magnesium, in combination with sulphuric acid so as to form sulphate of lime (plaster of Paris), and sulphate of magnesia. The former of these, the lime salt, is usually detected by the application of oxalate of ammonia, which also produces a white precipitate called oxalate of lime. The latter salt, sulphate of magnesia, is detected by the application of oxalate of ammonia, so as to first precipi- tate the lime salts : after filtering off this first precipitate,, the addition of a few drops of liquid ammonia and hypo- phosphate of soda, will throw down a further white pre- cipitate, which will indicate the presence of magnesium. Comparative Qualities. 18. To give an idea of the comparative qualities of water from their appearance, after testing with nitrate of silver, Table A is subjoined. It is supposed that a speci- men of distilled water is presented in an ordinary test tube, filled, say, three parts full of the distilled water to be tested. Having first acidified the specimen with a little nitric acid, let one drop of nitrate of silver (of 5 per cent, strength) fall into the water in the test tube. If chlorine is present, a white precipitate will be formed, varying from the slightest cloudiness to a heavy white mass. Note.—It should be observed that this precipitate will be somewhat different in character, according as the water tested is cold or hot. If the specimen of distilled water in the test tube is cold, the chloride of silver will be oh--