694 



SODA AND SODA COMPOUNDS. 



and (as the author states in his account of this 

 plan) to bisulphide of calcium and lime. 



In either of the two cases now considered, 

 soluble sulphur compounds result; and the 

 rains wash these out of the heap. Gutters 

 are accordingly formed around the latter and 

 the drainings conducted into large tanks or 

 shallow pits, in which they are allowed to 

 stand exposed to the action of the air. Ox- 

 idation goes on rapidly, the sulphides being 

 converted into oxygen salts ; though, whether 

 or not the sulphur to some extent escapes in 

 gaseous combination, is not stated. When the 

 sulphides have quite disappeared, in reference 

 to the case in which the oxidation in the heap 

 has been expedited, it is stated that the 

 liquor can at once be used as a tolerable ma- 

 nure ; wliile, as to drainings from heaps left 

 to spontaneous change, it is directed at such 

 point to remove the clear solution and decom- 

 pose hyposulphite of lime present in it by sul- 

 phate of soda, to procure the hyposulphite of 

 soda, after removing which, of course, the 

 liquid may be put to the same use as above in- 

 dicated. 



SODA AND SODA COMPOUNDS. The 

 fundamental parts of the process which, under 

 many modifications, is still most largely em- 

 ployed for the production on a manufacturing 

 scale of soda and its carbonates, are such as 

 depend on the discovery of M. Nicholas Le- 

 blanc, made in course of researches begun 

 in the year 1784, namely, that when sulphate 

 of soda (Glauber's salt) is calcined in due pro- 

 portions with chalk and charcoal, the result 

 is an alkaline mass, containing carbonate of 

 soda and caustic soda, both easily separable by 

 the action of water ; while nearly all the sul- 

 phur still present in the same mass is held 

 insoluble in calcium compounds that have com- 

 monly been regarded as constituting an oxy- 

 sulphide of that base. This process, setting out 

 with Glauher's formation of the sulphate of 

 soda by action of sulphuric acid on common 

 salt, was by a committee of the French Gov- 

 ernment selected as the most advantageous 

 among twelve different methods presented to 

 it, and was made public in the year 1791. 



Accounts at length of the soda-process of 

 Leblanc, as employed in practice, involving of 

 course many of the improvements, up to a re- 

 cent period made in it, will be found in various 

 encyclopaedias and technological works, as, un- 

 der the title SODA., in the NEW AMERICAN CYCLO- 

 PEDIA, and in the recent Supplement to fire's 

 Dictionary, etc. A brief outline of the principal 

 steps as now generally conducted, however, will 

 presently be given. The process itself, as carried 

 on under the best conditions, has still some ob- 

 jectionable features ; the most serious of which, 

 perhaps, consist in the facts, that the sulphur 

 of the residues cannot, except by complicated 

 an^ tedious processes, be recovered (in form of 

 80s) for re-use in the manufacture, so that the 

 consumption of the sulphuric acid employed is 

 continuous and very considerable ; and that, at 



large works, the residues accumulate in im- 

 mense quantities, being, from the amount of 

 sulphur in them, useless as fertilizing material, 

 at the same time that they give off sulphuretted 

 gases, and from the like cause render the rain- 

 water leaching from the 'heaps injurious to 

 vegetation, and to the fish of streams receiving 

 it. Circumstances of this nature, together with 

 the fact of the many reactions that, as con- 

 ducted in the laboratory, or on the small scale, 

 afford soda or its carbonates with apparent 

 facility and cheapness, have led to the at- 

 tempting of a variety of other methods, a few 

 of which are actually employed with success in 

 the manufacture. 



Synopsis of Processes for Preparation of 

 Soda, etc. M. Eodolph Wagner has given, in 

 Le Technologiste (December, 1864), a summary 

 though still not a complete one of the more 

 important soda-processes that have been pro- 

 posed or attempted, and mainly from which the 

 following synopsis is still further abridged. He 

 ranges his classification under the heads of the 

 five principal sources of soda, namely : 



1. Soda saltpetre, or the so-called cubic nitre 

 (nitrate of soda, NaO.NOs). 



2. Cryolite, the native double fluoride of so- 

 dium and aluminium (8NaFl.Al 2 Fl 3 ). 



3. Sulphate of soda (NaO.SO 3 ). 



4. Marine or common salt (NaCl). 



5. Albite, the soda-analogue of felspar, in 

 granite. 



The processes enumerated are the following : 



I. With nitrate of sodz calcination with 

 carbon (Duhamel) ; fusion with binoxide of 

 manganese (Wohler) ; decomposition with car- 

 bonate of potassa; calcination with sulphates 

 of lime and magnesia (Kuhlmann). 



II. With cryolite beginning with hydrate 

 of lime, and decomposing aluminate of soda by 

 carbonic acid ; beginning with hydrate of 

 baryta; treating with sodium with a view to 

 fabrication of aluminium, and decomposition of 

 fluoride of sodium by hydrate of lime (Tissier). 



III. With sulphate of soda : (A) DIRECTLY 

 decomposition of the sulphate, by acetate of 

 lime (Crell) ; by acetate of lead (Kirwan) ; by 

 carbonate of potassa (Hagen) ; by carbonate of 

 baryta (Kastner, Kolreuter, Lennig, Melseas, 

 etc.) ; by hydrated bicarbonate of baryta 

 (Wagner) ; by hydrate of baryta (Fuller, Sam- 

 uel) ; by acetate of baryta ; by hydrate of lime 

 (Claussen) ; (B) INDIRECTLY employing sul- 

 phide of sodium, with acetic acid, and calcining 

 (Duhamel) ; the same, with peroxide of iron 

 (Malherbe, Kopp) ; the same, with moist car- 

 bonic acid (Gossage) ; the same, with car- 

 bonate of ammonia (Laming) ; the same, with 

 caustic lime (Leblanc?); the same, with car- 

 bonate of iron (Habich); the same, with oxide 

 of copper (Pruckner and Persoz) ; the same, 

 with baryta (Eeinar) ; the same, with sulphate 

 of lead (Colard; ; (C) PREPARATION OF THE SUL- 

 PHATE from common salt and sulphuric acid 

 (Glauber) ; from the mother-liquors of salt- 

 works ; from sea- water (Balard, Merte) ; froo 



