ALKALIES. 253 



phur, which is often to a degree separated by the efflorescence of 

 the soda,* in the form of carbonate. 



When soda plants are made to vegetate away from saline sources, 

 the quantity of soda constantly diminishes, and eventually they afford 

 only potash. Murray. Although soda is separated from its com* 

 binations with acids by potash, it exceeds that alkali in its power of 

 neutralizing acids, in the proportion of 4 to 6, or 2 to 3, its equiva- 

 lent being 32, and that of potash 48. 



Mode of ascertaining the proportion of real alkali in the soda 

 of Commerce. 



Take sulphuric acid of the specific gravity of 1.10, w^hich is gene- 

 rally prepared by mixing one part, by weight, of the best acid of the 

 shops, with six of water. 



Pulverize finely, an average sample ; take, say 100 grains, and 

 add to it 2 oz. measures of pure water, agitating it occasionally, for 

 a few hours ; after subsidence, decant, add more water, and again 

 allow the solid matter to subside ; decant again, and filter the fluids, 

 and lastly, wash the solid residuum on a filter, until the water drops 

 tasteless, and no longer affects the test colors. Mix the different 

 fluids, and concentrate them, by boiling, to the volume of 2 or 3 oz. 

 measures. In a vial of known weight, place 2 oz. of the acid, sp. 

 gr. 1.10, and then add it cautiously to the alkali, till effervescence 

 ceases, and the test papers are no longer altered. Sulphur will be 

 precipitated. Now see how much acid remains. It having been 

 ascertained by previous trials, that 100 grains of dry alcoholic potas- 

 sa, require 520 grains of the acid, of the sp. gr. 1.10, for saturation, 

 and that 100 grains of alcoholic soda require 812 grains of the same 

 acid, it is easily calculated how much real alkali there was in the por- 

 tion subjected to examination. Trial is made also, for potash, and 

 the test used is muriate of platinum ; there will be a yellow precipitate 

 if potash is present ; otherwise none. If muriate of potash should 

 be suspected, since the muriate of platinum detects all the salts of 

 potash, it may be knovvn by adding a little sulphuric acid to the alka^ 

 line lixivium, when there will be fumes of muriatic acid gas, if the 

 muriate of potash is present. f 



SODIUM. 



1. DISCOVERY. By Sir H. Davy, at the same time with potas- 

 sium, October, 1807. 



* Mr. Parkes, in his essays, mentions that some dealers refuse to buy theefflores- 

 ced carbonate of soda, thinking it to be spoiled, whereas it is really in a good degree 

 purified. 



t Parkes' Cheru. Essays, Vol. II. 



