30 Mr. J. Brown on the Products of the Soda Manufacture. 



Lime. Sulphur. ""^P^}' 



Carbonate of lime 



3CaSCaO 



Carbon 



Silicate of magnesia . . 



Sand 



Peroxide of iron 



Sulphate of lime , 



Hyposulphite of lime. . 

 Bisulphuret of calcium 

 Sulphuret of calcium.., 



Hydrate of lime 



Carbonate of soda 



Water (hygroscopic) .., 



21-220 

 20-363 

 12-709 

 5-987 

 5-746 

 5-716 

 4-281 

 trace 

 3-583 

 8-527 

 5-583 

 1-309 

 2-100 



13-563 

 16-769 



1645 



1-929 

 6-631 

 4-225 



10-657 



7-187 



2-205 

 3-790 



0-533 



100-124 



44-762 



13-182 



11 190 



As might be expected, the quantities of lime, sulphur and 

 carbonic acid, are subject to great variations, every sample 

 varying to a considerable extent. 



Upon examining a sample of waste three or four weeks old, 

 I found the quantity of hyposulphite of lime to be much greater 

 than in perfectly fresh waste. Another specimen, which had 

 been partially exposed to the action of the atmosphere for 

 three years, was entirely converted into sulphate of lime, 

 sulphite of lime and carbonate of lime, and hyposulphate of 

 lime. Some specimens were obtained which consisted entirely 

 of sulphate of lime, carbonate of lime and causticlime. These 

 experiments are very interesting from their showing the gra- 

 dual oxidation of the sulphur which the waste contains. 



The waste in the soda ball consists entirely of oxysulphuret 

 of lime (SCaS, CaO) and caustic lime. The SCaS, CaO soon, 

 however, decomposes, giving rise to sulphuret and bisulphuret 

 of calcium and caustic lime. The bisulphuret of calcium 

 being very efflorescent, forms on the waste heap a yellow coat- 

 ing of small prismatic crystals. The sulphur is then further 

 oxidized, the first products being hyposulphite and sulphite 

 of lime: the process still continuing, hyposulphate and sul- 

 phate of lime are formed ; and this oxidation goes on till 

 sulphate of lime remains. The caustic lime is also for the 

 most part converted into carbonate. 



It would be very interesting to ascertain the exact amount 

 of each of these substances present in waste in different stages 

 of decomposition ; but there are as yet no methods known 

 by which sulphurous, hyposulphurous, and hyposulphuric 

 acid can be accurately determined, especially when existing 

 along with sulphuric acid and sulphurets, as in soda waste. 

 Under these circumstances, it would be impossible to make a 



