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



( Sulphate of lime, 4-281 1*645 — — 



Hyposulphite of lime, trace — — — 



Bisulphuret of calcium,.... 3*583 1*929 2-205 — 



Sulphuret of calcium, ... . 8*527 6-631 3*790 — 



Hydrate of lime, 5*582 4*225 — — 



Carbonate of soda, 1*309 — — 0*533 



Water (hygroscopic), 2*100 — — — 



3^ 

 a 



1 



99.492 44*762 13*182 11190 



As might be expected, the quantity of lime, sulphur, and carbonic acid 

 is 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 sul- 

 phate of lime, sulphite of lime, carbonate of lime, and hyposulphate 

 of lime. Some specimens were obtained which consisted entirely of sul- 

 phate of lime, carbonate of lime, and caustic lime. These experiments 

 are very interesting, as they show the gradual oxydation of the sulphur 

 which the waste contains. 



The waste in the soda ball consists entirely of oxysulphuret of lime 

 (3 CaS CaO,) and caustic lime. The 3 CaS CaO soon, however, decom- 

 poses, 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 coating of small prismatic crystals. The sulphur is 

 then further oxydized, the first products being hyposulphite and sulphite 

 of lime : the process still continuing, hyposulphate and sulphate of lime 

 are formed; and this oxydation 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, hyposul- 

 phurous, 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 series of 

 analyses of the waste in its different stages of decomposition, upon which 

 perfect dependence could be placed. But it is to be hoped, that as the 

 science advances, these at present insuperable obstacles may be entirely 

 removed. 



The following is an analysis by Unger of a sample of waste from 

 Cassel : — 



