18 Mr. J. Brown on the Products of the Soda Manufacture. 



salt was then repeatedly washed with boiling water. The 

 iodide and bromide were thus taken up by the water along 

 with a large quantity of common salt. This solution was eva- 

 porated to dryness and the residue digested in alcohol, which 

 dissolved the iodide and bromide along with a little of the salt, 

 leaving, however, the greater part of it, which was afterwards 

 separated by filtration. The filtered solution was again eva- 

 porated to dryness and the residue digested in water. Chlo- 

 ride of palladium was then added, but no precipitation of 

 iodide of palladium took place. The palladium was preci- 

 pitated by sulphuretted hydrogen, and the sulphuret of palla- 

 dium thus formed separated by filtration. Upon testing the 

 filtered solution with ammonia and nitrate of silver, no preci- 

 pitate was obtained. Had bromine been present, it would 

 have been precipitated in combination with the silver, bromide 

 of silver being insoluble in caustic ammonia. It is therefore 

 evident that the common salt manufactured, as previously men- 

 tioned, does not contain iodine or bromine, although it is 

 highly probable that these bodies are present in small quantity 

 in rock salt; and we might therefore be able to detect them 

 in the brine from which the magnesia salts are manufactured. 

 Upon treating the salt with bichloride of platinum a slight 

 precipitate of potassio-chloride of platinum was obtained. 



Composition of Commercial Salt. 



About 6 cwt. of this salt is introduced into an iron pot, and 

 upon this is run, by a siphon, about 5| cwt. of sulphuric acid 

 of about 1*7.50 specific gravity (150° Twaddell). A violent 

 action immediately takes place, and large quantities of muriatic 

 acid gas are evolved, which pass off by a chimney. If, how- 

 ever, the muriatic acid can be made use of, the gas is absorbed 

 either by passing it tnrough water contained in large cylin- 

 drical vessels or through a column of coke, which retains the 

 gas until a considerable quantity of it is collected; a stream 

 of water is then allowed to trickle through the coke, and in 



