SODA AND SODA COMPOUNDS. 



C97 



In respect to tlio chemiral character of the 

 mainly iii-M.ail.K- rv-idiies exi>ting along with 



::i tlio crude ball alkali, M. Scheurer i 

 Her lias very recently declared that his anal- 

 yse* do not show in those residues tlio pr> 

 (!' an oxyMilphMe nt' calcium, hut rather of 

 :g proportions of oxide, carbonate, and 

 i rahiuin, depending:, as he implies, 

 on the proportions of the chalk and sulphate 



a the manufacture. Pelouze, (!< 

 Kyna.-tnn, ami others au'ree in this opinion, that 

 ;!phur of the residues is not present in an 

 oxysulphide. 



M. Peloazo expresses, at, the close of a paper 



on the theory of Loblanc's process, before the 



Academy of Sciences, February 12, 1866, the 



following as the conclusions to which his anal- 



1 his study of the subject lead : 



1. That " black ash " is a mixture of car- 

 bonate of soda, sulphide of calcium, carbonate 

 of lime, and free lime. 



2. The ash, on prolonged contact with water, 

 hot or cold, gives an amount of caustic soda 

 proportional to the free lime the ash contains, 

 and then the lime in the waste is completely 

 neutralized by sulphydric or carbonic acid. 



3. This reaction with the carbonate of soda 

 not usually being complete, the waste will com- 

 monly contain some free lime. 



4. Any black ash being given, free lime may 

 be left in the waste, or not, just as the lixivia- 

 tion is managed. 



6. Nothing has yet demonstrated the exist- 

 ence of an oxysulphide of calcium, nor of any 

 other compound of lime with sulphide of cal- 

 cium. (Chem, News, February 23, 18G6.) 



M. Verstraet details at length, in Le Techno- 

 logiste for April, 1865, a convenient method of 

 te-ting accurately the quantity of sulphide of 

 sodium present in a lye of crude soda. 



Other Processes with Sulphate of Soda. 

 Among the modifications of Leblanc's soda- 

 process, at least in its first stage, and which 

 lieen to some extent brought into success- 

 ful practice, are those of obtaining the sulphate 

 of soda by heating green vitriol (sulphate of 

 iron) with common salt, the chloride of iron, 

 which simultaneously forms, being volatilized; 

 and of roasting, with common salt, copper or 

 iron pyrites the latter affording a means of 

 using ores otherwise too poor to bo worked 

 with profit. (UfiE.) 



In the method devised by M. E. F. Anthon, 

 of Prague, equivalent quantities of marine salt, 

 gypsum (sulphate of lime), and calcined mag- 

 nesia are mixed with a quantity of water of six 

 or eight times the weight of the salt, a current of 

 carbonic acid is introduced and the mixture kept 

 agitated : carbonate of magnesia forms, reacting 

 with gypsum to produce carbonate of lime and 

 sulphate of magnesia, the latter of which react- 

 ing in turn with the common salt, gives sul- 

 phate of soda and chloride of magnesium. The 

 lime-salt precipitates, and the liquid being prop- 

 erly evaporated, the sulphate of soda crystal- 

 lizes, while the chloride of magnesium remains 



in solution. Jour, of Soc. of Artt. August, 

 18(14. 



Mr. A. G. Hunter, Englapd, patented in 

 April, 1865, a method of converting sulphate 

 of soda or potassa into the corresponding car- 

 bonate, by boiling under pressure (hydraulic, 

 steam, 'or mechanical) a mixture of caustic 

 lime, in form of milk of lime, with a 

 weak solution of the sulphate of the alkali 

 in case of sulphate of soda, specific gravity 

 1.1, and pressure 40 to 50 Ibs. to the square 

 inch. When caustic alkali has resulted, the 

 sulphate of lime, insoluble, may b; separated 

 by filtration, still under pressure, to be sold as a 

 fertilizer, or purified for special uses. Methods 

 of carbonating the alkali are also given. New- 

 ton's Lond.Jour., April, 1866. 



The methods of Macfarlane and Kopp, next 

 to be considered, also involve the use or pro- 

 duction of sulphate of soda. 



Preparation of Soda, Chlorine, and Sulphuric 

 and Chlorhydric Acids. In this process, de- 

 scribed by Mr. T. Macfarlane in the Canadian 

 Naturalist (February, 1863), sea-salt is decom- 

 posed, with fabrication of the substances named. 

 Green vitriol, dried and mixed with sea-salt, ia 

 heated to redness in a current of air, with for- 

 mation of a sesquichloride of iron, and then of 

 peroxide (sesquioxide) of iron and free chlorine : 

 the solid residue consists of the last-named per- 

 oxide with sulphate of soda. The reaction is 

 facilitated by previous admixture of some per- 

 oxide of iron. 



In carrying out the process, 828 parts of green 

 vitriol, dried and partly peroxidized at a gentle 

 heat, are intimately mixed with 352 parts of 

 sea-salt and 78 of peroxide of iron ; and the 

 whole is then heated to low redness in a muffle 

 calcining furnace, through which a current of 

 air dried by passing over quicklime is maintain- 

 ed, the mixture being stirred, and the heat kept 

 so low as not to sublime any chloride of iron. 

 The decomposition of the chloride of sodium is 

 stated to be complete, the muffle containing a 

 mixture of peroxide of iron and sulphate of 

 s :!a. and the chlorine gas given off, though 

 mixed with nitrogen, being available for the 

 preparation of bleaching salts, etc. The solid 

 re.-idue is ground, mixed with 144 parts of coal, 

 and heated to fusion in a reverberatory furnace, 

 the hearth of the latter being prepared sub- 

 stantially of quicklime mixed with a little basic 

 slag or glass, and saturated with sulphide of 

 soilium. The fused mass, treated after cooling 

 with water, yields sulphide of iron, and an im- 

 pure caustic soda from which more of the same 

 sulphide is precipitated by carbonic acid : the re- 

 maining solution of carbonate of soda and caus- 

 tic soda is to be treated by the ordinary methods. 



The sulphide of iron residue from the pro- 

 -. washed, and exposed moist to the action 

 of the air: by action subsequently of water, 

 sulphate of iron is dissolved from the mass, and 

 peroxide of iron separated; and the former 

 being obtained dry, these two materials aro 

 available in operating on a new portion of salt 



