OF SEA-WATEB. 213 



A small portion of liquor remained, which, by farther evapora- 

 tion, yielded crystals of sulphate of soda to the amount of 6 

 grains, with crystals of muriate of soda 2 grains. 



The portions of muriate of soda obtained in the preceding 

 experiments amounted to 765.1 grains. None of them, how- 

 ever, were perfectly pure. Their solutions became turbid on* 

 the addition of sub-carbonate of soda, and of muriate of ba- 

 rytes, indicating the presence of sulphate of magnesia, or of 

 muriate of magnesia and sulphate of soda, and probably indeed 

 of portions of all these. The whole was submitted to the ac- 

 tion of highly rectified alcohol for 12 hours, with repeated agi- 

 tation ; the alcohol acquired a bitter taste ; being poured off, 

 and distilled, it afforded muriate of magnesia, which, heated 

 with sulphuric acid, gave a product equivalent to 6.2 of real 

 muriate. The residual salt still gave indications of the pre- 

 sence of sulphate of magnesia, by the tests of muriate of ba- 

 rytes and sub-carbonate of soda. The difficulty is so great, of 

 separating a small portion of a salt from a large quantity of 

 another, where the difference in their solubility is not consider- 

 able, that instead of attempting to remove the sulphate of mag- 

 nesia by farther crystallizations, it was decomposed by adding 

 to the solution sub-carbonate of soda ; the precipitate was col- 

 lected, and converted into sulphate of magnesia by the addition 

 of sulphuric acid. This, dried at a low red-heat, weighed 16 

 grains, equivalent to 33 crystallised. The salt had been previ- 

 ously exposed to a red-heat, when it weighed 744.5 grains. 

 The above quantity of sulphate abstracted from this, leaves as 

 the real quantity of muriate of soda 728.5 grains. 



The powder G was soft, light, and tasteless. It weighed 

 when thoroughly dried 7.5 grains. It might be expected to be 

 similar to the powder A, and was therefore subjected to the 

 same treatment. Diluted alcohol, acidulated with muriatic 



acid, 



