48 ON THE PREPARATION OP SODA AND CHLORINE. 



it a waste product of chloride of manganese ; 4th. The decom- 

 position of sulphate of soda by igniting it with limestone and 

 charcoal, in which operation the sulphur combines with lime, for- 

 ming with it a waste product of sulphuret of calcium ; 5th. The 

 extraction of carbonate of soda and soda-ash from the product of 

 this ignition. With regard to these, the ordinary processes, the 

 following facts are to be observed. — I. The whole of the sulphur 

 contained in the sulphuric acid, and one half of the chlorine 

 contained in the common salt originally used are lost. 

 II. They comprise five distinct purposes, some of which, such as 

 the manufacture of sulphuric acid, require very expensive appara- 

 tus. III. Nitrous acid, peroxide of manganese, and limestone are 

 used in these process, in such a manner as not to be economically 

 recovered, or only with great difficulty. In comparing these pro- 

 cesses with the new method it will be observed : I. That by means 

 of the latter the suiphur combined in the sulphuric acid of the 

 green vitirol used in the first part of the process is recovered, and 

 may be used an indefinite number of times ; and that the whole of 

 the chlorine contained in the common salt is evolved as gas, and 

 rendered available for the manufacture of bleaching powder. II. 

 that the new method comprises only four processes, one less than 

 by the ordinary mode, and that these do not require any extraor- 

 dinarily expensive apparatus. III. That nitrous acid, peroxide of 

 manganese, and limestone are altogether dispensed with ; only one 

 material, peroxide of iron, being used in place of the limestone, but 

 always in such a manner as to be recovered and used again. It 

 will of course be evident that the advantages here enumerated re- 

 sult to some extent from the combination of what has above been 

 termed the three different parts of the process. They form to- 

 gether an independent method for making bleaching powder and 

 soda without the intervention or auxiliary manufacture of sulphu- 

 ric and muriatic acids, or the necessity of using more than the one 

 principal raw material, viz., common salt. 



With regard to the new method of manufacturing sulphuric and 

 muriatic acids, it is based upon the following chemical reaction — 

 when sulphuric acid and chlorine gases in the proportion of their 

 equivalents are brought in contact with water or steam, the oxygen 

 of the latter unites with the sulphurous acid, forming sulphuric acid, 

 while the hydrogen forms with the chlorine, muriatic acid. The ma- 

 nufacture of these acids on this principle was, in 1854, embodied in 



