98 On the Decomposilion of the Muriate of Soda. 



disturbances in Spain, has rendered it so scarce that its value 

 has been ot late doubled. 



The French government, however, ha? felt the importance 

 of encouraging the uianutacture of this article at home, 

 and the imposts on nuinale of soda emplo\cd for such 

 purposes have been accordingly removed. 



The process most in use for the preparation of soda con- 

 sists, 1st. in freeing the muriatic acid from sea salt, and 

 forming a sulphate of soda : 2d, in decomposing the sul- 

 phate of soda, by the iniern;edium of chalk and charcoal. 



The last of these operations is aiuays the same, the first 

 only being variable. 



In most establishments, the sulphuric acid is employed 

 jn the decomposition of the nuiriate of soda. The propor- 

 tion for a metrical quintal of sea salt is a quantity of sul- 

 phuric acid at 43°, represcming a metrical quintal at 66^ of 

 'J3caume's areometer. 



If on the one hand this operation is the simplest and 

 most expeditious, since we speedily form dry sulphate of 

 soda, it is on the other hand very expensive, as tiie sulphur, 

 the base of the sulphuric acid, is a foreign product, which is 

 procured with difficulty even at the cxtravagent price of 

 140 francs for 100 kilogrammes. 



It mav be easily conc"eived, therefore, that these new esta- 

 blishments are precarious, that ihey may be occasionally 

 paralysed, and that at the conclusion of peace they could 

 not come in competition with those of other countries. 



The onlv method of avoiding this inconvenience would 

 be to substitute some indigenous substance for the sulphuric 

 acid, and this is the object which I have had in view. 



After manv experiments, the process which appeared to 

 ine to be most advantatreous consists in substituting for the 

 sulphuric acid the waters produced by the lixiviation of 

 the efflorescent vitriolic earths. When there is a proper 

 proportion of these waters, and the operation isv/ell managed, 

 ■we effect a complete decomposition of the muriate of soda, 

 and obtain for 100 parts of dry and pure muriate of soda, 

 107 of dry sulphate of soda, or 213 of crystallized sulphate 

 of soda*. 



The vitriolic waters which I have hitherto employed for 

 the extrication of sea salt come froni the black pyritous 



earths 



• According to the experiments made on a large scale, hy order of the 

 CorriTTiittee of Publi; S.i t-ty, it w.i- asceiiaincd that tlic 5iil^!;uric acid might 

 l)e dispensed with on usinjj the sulphurei of iron or the bulphate of iron ; 

 but v-e do not procure i'V ihesc ayciits ths entire decomposition of the mu- 

 fiste of soda, vvtiercas by the vitriolic waters the v.hole of the muriate of 



K>d4 



