Mr. J. Brown on the Products of the Soda Manufacture, 17 



3rd. The soda-ash process. 



-ith. The carbonate of soda process. 



I. The first stage which thus comes under our consideration 

 is — The decomposition of common salt by sulphuric acid, causing 

 the formation of sulphate of soda and muriatic acid. 



The salt used in this process is obtained from the brine- 

 springs of Cheshire, which exist abundantly in tiie new red 

 sandstone of that county. The sohition is evaporated^ till it 

 reaches a certain strength, when all the salt precipitates ; it is 

 then raked out into wicker baskets and allowed to drain. The 

 mother-liquor is used for the manufacture of the salts of mag- 

 nesia. The salt thus obtained contains, as might be expected, 

 numerous impurities, the principal of which ai'e lime, sulphuric 

 acid and magnesia. 



To estimate the lime, a portion of the salt was dissolved in 

 water, and after separating the insoluble matter by filtration, 

 the lime was precipitated by ammonia and oxalic acid, a large 

 quantity of muriate of ammonia being added to retain the 

 magnesia in solution. 



CaO, COj. CaO. CaO per 1 000 gis. 

 2000 grains of salt gave 15-10 8-456 4*228 



14-60 8-176 4-088 



Average 4 158 



The sulphuric acid was precipitated by the addition of nitric 

 acid and nitrate of barytes. 



BaO, SO3. SO3. SO3 per 1 000 grs. 

 2000 grains of salt gave 39-85 13-738 6-869 



39-50 13-620 6-810 



Average 6-839 

 The quantity of magnesia was ascertained by precipitation 

 by ammonia and phosphate of soda, the lime having been pre- 

 viously separated. 



2MgO,P2 0A. MgO. MgO per 1000 grs. 



2000 grains of salt gave 465 1-660 0-830 



The carbonate of lime remained as insoluble matter when 

 the salt. was digested in water, and was separated by filtration. 



CaO, CO.. CaO, CO2 per 1000 grs. 

 2000 grains of salt gave 3-000 1-50 



By estimating the amount lost by drying the salt at 212° 

 the quantity of water was ascertained. 



Water per 1000 grs. 

 330-2 grains of salt lost 17-96 54-373 



In order to estimate the quantity of iodide of potassium and 

 bromide of magnesium, li lb. of salt was put into a funnel, 

 the lower end of which was closed with filtering-paper. The 



Phil. Mag. S. 3. Vol. 34. No. 226. Jan. 1849. C 



