74 ANNUAL OF SCIENTIFIC DISCOVERY. 



great interest to English readers, but we may mention that when the 

 liquor remaining after the fermentation and distillation of beet-root 

 molasses is boiled down, incinerated, and the charred mass lixiviated, 

 a considerable amount of potash salts is obtained. The molasses 

 contains from 10 to 12 per cent of its weight of salts, more than half 

 of which are alkaline. 



The home sources to which English manufactures have to look for 

 their potassium compounds are sea- weeds and the primitive rocks. 

 The first of these sources has long been worked, and the industry is 

 well understood. Nevertheless, the methods employed for obtaining 

 the salts have been found capable of much improvement, which it has 

 received at the hands of Mr. E. C. Standford and others. Sea-water, 

 we should remark, may always be looked to as a source of potash, 

 but this is of the less importance to us in consequence of our sources 

 of common salt. 



The account of M. Balard's process, with the modifications intro- 

 duced by M. Merle, for separating the saline constituents of sea- 

 water, will be perused with interest by all scientific readers. Sea- 

 water is first concentrated to 28 Baumo (or T24 sp. gr.), at which 

 degree four-fifths of the chloride of sodium is deposited. There 

 remain in solution with the other chloride of sodium, sulphate of 

 magnesium, and chlorides of potassium and magnesium. M. Merle 

 now avails himself of M. Carre's refrigerating machine. The mother 

 liquor, a little diluted, is made to pass in a continuous stream through 

 refrigerating vessels constructed on M. Carre's principle, by which 

 the liquor is cooled to 18 C. At this temperature a double de- 

 composition takes place between the sulphate of magnesium and 

 chloride of sodium, sulphate of sodium being deposited, and the 

 chlorides of magnesium, sodium, and potassium passing away in the 

 solution. To separate these chlorides the solution is then boiled 

 down to 36 B., at which nearly the whole of the chloride of sodium 

 is deposited in a fine powder. The hot liquor from this is next run 

 off into shallow coolers, Avhen the whole of the potash is deposited in 

 the form of a double chloride of potassium and magnesium, from 

 which the magnesium salt is removed by washing the mass with half 

 its weight of water. In this way | of the chloride of potassium are 

 obtained in a tolerable state of purity. Our readers will see that no 

 account is here taken of the bromides and iodides, which, indeed, 

 are thrown away with the chloride of magnesium. 



The small amount of potassium salt in proportion to the sodium 

 compounds obtained from sea-water will of course limit this industry 

 to those countries in which the latter compounds have a higher rela- 

 tive value than in England. We mav look with much more interest 



^j / 



to our mineral sources of potassium in the primitive rocks. Many of 

 our readers no doubt have some acquaintance with a process for 

 estimating the alkalies in felspathic rocks, which consists in calcining 

 the mineral with a mixture of fluorspar and carbonate of lime, and 

 washing out the alkalies which have become carbonated in the calci- 

 nation. The great objection to this as an analytical process is that 

 the calcination must be repeated two or three times in order to be 

 certain of removing the whole of the alkalies, all of which may, how- 

 ever, be removed in a single washing. It is this process which 



