272 Mr. Brown on the Products of the Soda Manufacture. 



of water is certainly formed in the combustion of coal, but this is not 

 sufficient to account for it. The method of analysis pursued in the 

 determination of the amount of water combined with soda or lime was, 

 I think, very incorrect. It was to burn the ball soda with chromate 

 of lead, and determine the weight of the water given off. Had any 

 un decomposed coal existed in the waste, it would have contained hydro- 

 gen, and water would consequently have been formed, the oxygen being 

 derived from the chromic acid of the chromate of lead. 



As might be expected, I found, upon trying samples taken from dif- 

 ferent furnaces, that the constituents were subject to great variations. 

 Thus, the lime varied from 27 to 34 per cent. ; the soda from 22 to 265 

 per cent. ; the sulphur from 10 to 16 per cent. ; — but they always stood 

 in a certain fixed relation to one another ; for when the quantity of lime 

 was large, the amount of sulphur was proportionally increased, and the 

 per centage of soda consequently diminished. The following table will 

 suffice to show this : — 



I. II. III. 



Soda, 26-480 22-000 24-138 



Lime, 26-959 33-807 30-324 



Sulphur, 10-527 13-820 12-436 



I insert here two analyses of soda balls, the one from Cassel by Unger, 

 the other from Newcastle by Richardson. They both get hydrate of 

 soda and carbonate of lime, and are I think wrong in both of these, 

 although the other parts of the analyses are probably quite correct. 



The manufacture in Cassel and Newcastle is carried on almost exactly 

 in the same way as here. 



From Cassel. From Newcastle. 



Sulphate of soda, 1*99 3*64 



Chloride of sodium, 2*54 0*60 



Carbonate of soda, 23-57 9*89 



Hydrate of soda, 11*12 25*64 



Carbonate of lime, 12*90 15*67 



3 CaS, CaO, 34*76 35*57 



Sulphuret of iron, 2*45 1*22 



Silicate of magnesia, 4*74 0*88 



Charcoal, 4*59 4*28 



Sand, 2*02 0*44 



Water (hygroscopic,) 2*10 2*17 



99*78 100*00 



This brings us to the consideration of the third division of the soda 

 process, namely, — 



III. The Manufacture of Soda Ash from Ball Soda. 



The first point is to extract all the soluble matter from the balls. 

 This is done by digestion in warm water. The vessels used for this pur- 

 pose are large square iron pans, five or six of which are usually worked 



