20 -^n /Analysis of Sea-water ; 



acid, £;avc 5 -6 of sulphate, equivalent to 4*3 of carhonate of niag- 

 iiesia,\ind 3 of suipliate, equivalent to 2-2 of carbonate of lime. 

 I have already observed, hou-ever, that no carbonic acid is de- 

 tected in sea-water by the test of barytes ; these carl)onateSy 

 therefore, are, as before, to be considered as products of the eva- 

 poration, arisincT from the decomposition of muri;ite of magnesia, 

 and of muriate or sulphate of lime. The one, but for tlie de- 

 composition by which it is produced, would have appeared as 

 suli)hate of lime; it increases, therefore, the proportion of that 

 ingredient to 29-3 grains. The portion of muriate, equivalent 

 to the oth.er, that is, 4-4 grains, may be added to the quantity 

 of that salt obtained in the subsequent steps of the analysis. 



F. The products of the different crystallizations Pj, consisting 

 chiefly of sulphate of magnesia, with portions of muriate of 

 magnesia, were left exposed to the air for some days, and the 

 liquor formed from them by delicjuescence was poured off oc- 

 casionally, and added to the solution of nmriate of magnesia C. 

 The residues were then washed with pure alcohol, to abstract 

 more complctelv any muriate of magnesia. The portions re- 

 maining undissolved, were dissolved together in water. By 

 evaporation, they afforded sulphate of magnesia iu bevelled 

 prisms ; by further evaporation, muriate of soda in cul)es was 

 obtained ; and by successive evaporations, there were thus pro- 

 cured sulphate of magnesia in crystals, 46 6 grains ; and mu- 

 riate of soda 39 grains. A small portion of liquor remained, 

 which, containing chiefly muriate of magnesia, was added to the 

 liquor C. 



G. This liquor C, to which the portion of liquor formed by 

 deliquescence from B had also been added, was evaporated to 

 dryness. It was then submitted to the action of successive por- 

 tions of alcohol, employing, first, the alcohol with which the 

 saline matter B had been lixiviated, and afterwards pure alcohol. 

 These liquors, poured off from a portion which remained undis- 

 solved, were evaporated to dryness ; the dry mass was dissolved 

 in water, and, bv a second evaporation, afforded a congeries of 

 prisms of iminate of masnesiu. Dried by a heat of 150°, the 

 weight amounted to 156 grains. Converted into sulphate of 

 magnesia by the addition of sulphuric acid, the product weighed, 

 after being dried at a low red-heat, 99*2 grains, equivalent to 

 78*4 of real muriate of magnesia. 



H. The matter which remained midissolved by the alcohol G 

 was dissolved in distilled water. The solution was evaporated, 

 until, bv a further spontaneous evaporation in a warm apart- 

 ment, crystals were successively formed ; these were sulphate of 

 magnesia, and, in general, bevelled prisms. The whole fieed 

 from moisture weighed 48*6 grains. A small portion of liquor 



remained, 



