520 Dr. Leeson on the Preparation of Fluoride of Iodine. 



The chloride of manganese being one of the salts from which 

 a considerable number of the other compounds of the metal 

 are obtained, I shall first describe the method for its purifica- 

 tion. 



The common black oxide of manganese having been boiled 

 in muriatic acid, so as to obtain the solution as neutral as pos- 

 sible, it is to be filtered when cold, and then to have added to 

 it a solution of carbonate of ammonia, by which the iron will 

 be precipitated as a brownish powder ; and provided care be 

 taken not to add an excess, the whole of the manganese will 

 remain in solution ; this of course can be easily ascertained by 

 testing the filtered liquid with ferrocyanide of potassium. The 

 liquid will now hold in solution the chloride of manganese, 

 along with a small quantity of chloride of ammonium, which 

 latter substance is to be got rid of by evaporation to dryness, 

 and exposure to a temperature of 500*^ or 600°. 



The sulphate of manganese may be obtained free from iron 

 by following the same mode of purification. 



For the preparation of the carbonate of manganese the pro- 

 cess may be slightly modified, and a less expensive salt sub- 

 stituted for the carbonate of ammonia. The solution of im- 

 pure chloride or sulphate of manganese is to have carefully 

 added to it a solution of carbonate of soda, until on testing the 

 liquid it is found that all the iron has been thrown down ; it is 

 next to be filtered, when a further addition of carbonate of 

 soda will cause the precipitation of the carbonate of manga- 

 nese free from iron. As the solution of the sulphate of man- 

 ganese is now used in dyeing, this, I think, would be found a 

 more oeconomical process than that at present followed for its 

 preparation. The carbonate of soda might be used for the 

 precipitation of the iron instead of the carbonate of ammo- 

 nia; the small quantity of sulphate of soda left in the liquid 

 would not be likely to interfere with the use of the salt in 

 dyeing. 



LXXXIII. Abstract of a Letter from H. B. Leeson, M.D., 

 on the Preparation of Fluoride of Iodine^. 



THE fluoride of iodine, of which I presented a specimen to 

 the Chemical Society on the 1st of April, was prepared 

 by passing the gas generated from 1 part of peroxide of man- 

 ganese, 3 of pure fluor spar, and 6 of concentrated sulphuric 

 acid through water, in which the iodine was diffused (con- 

 tained in a glass vessel) until the whole of the iodine was taken 

 up. A leaden retort and conducting tube was made use of. 



• Communicated by the Chemical Society ; having been read May 20, 

 1844. 



