•27* 1 Mr. Brown on tin- PtodmcU of the Soda Manufacture. 



tho two experiments gave the amount of carbonic acid equivalent to the 

 quantity of soda existing as hydrate and sulphuret in the sample. The 

 amount united to sulphur was then deducted, and the remainder gave 

 the per centage of hydrate. 



4. Sulphate of soda. 



A portion of the salt was dissolved in a pretty large quantity of water, 

 and nitric acid added to expel the carbonic acid. The sulphuric acid 

 was then precipitated by chloride of barium. 



5. Sulphite of soda. 



The salt was boiled with strong nitric acid, in order to oxydize the 

 whole of the sulphite of soda and sulphuret of sodium. Water was then 

 added, and the sulphuric acid precipitated by a salt of barytes. From 

 the quantity of sulphate of barytes thus obtained, the amount got by the 

 former experiment was deducted, and the remainder showed the quantity 

 of sulphate of barytes equivalent to the amount of sulphite of soda and 

 sulphuret of sodium. The per centage of sulphuret of sodium being known, 

 the sulphite of soda was easily determined. 



6. Chloride of sodium. 



After expelling the carbonic acid by nitric acid, the chlorine was pre- 

 cipitated by nitrate of silver. 



7. Aluminate of soda and insoluble matter. 



A solution of the salt was acidified by muriatic acid, and the insoluble 

 matter (principally sand) separated by filtration. From the filtered 

 solution, the alumina was precipitated by caustic ammonia. 



The salt obtained by evaporation from the liqour from the keaves, after 

 drying at 212°, yielded on analysis, — 



I. II. 



Carbonate of soda, 68*907 65-513 



Hydrate of soda, 14*433 16*072 



Sulphate of soda, 7-018 7*812 



Sulphite of soda, 2*231 2-134 



Hyposulphite of soda, trace trace 



Sulphuret of sodium, 1*314 1*542 



Chloride of sodium, 3*972 3*862 



Aluminate of soda, 1*016 1*232 



Silicate of soda, 1*030 0*800 



Insoluble matter, 0*814 0*974 



100*755 99-961 



This salt is then introduced into a reverberatory or carbonating furnace, 

 where it is strongly heated. In this process the sulphuret of sodium is 

 converted into sulphate of soda, and part of the hydrate of soda into 

 carbonate. The salt, when removed from the furnace, is ready for the 

 market. In Newcastle and some other places, it is dissolved and car- 

 bonated again; and when thus manufactured, it contains less caustic 

 soda. Soda ash thus prepared contains from 48 to 53 per cent, of avail- 



