1846.] Hyposulphite of Soda — Hydrochloric Acid. 329 



PREPARATION OF HYPOSULPHITE OF SODA. 



BY M. V. LEGRIP. 



The author (rives the following as a good and cheap process u 

 the preparation of hyposulphite of soda, now so extensively em- 

 ployed in taking Daguerreotype images : — 



Take of Subcarbonate of soda - - 730 } arts 



Sulphur 45 " 



Water 1500 " 



Mix the sulphur first, with a small quantity of the water, and then 

 add the soda dissolved in the remainder of the water. Introduce 

 the mixture into two two-necked bottles, which shall not be mo.e 

 than two-thirds fdled, then, 



Take of Clean iron filings - - - - 1,500 parts 

 Sulphuric acid,"(sp.gr. 1.845) 3,000 " 



Put these into a flask capable of holding two or thice times 

 the above quantity. Allow the mixture to cool, and the first por- 

 tion of disengaged hydrogen to escape, then place the flask on a 

 sand-bath, and by means of tubes of rather large diameter, convey 

 the gas, first into a washing bottle, and then through the two- 

 necked bottles containing the solution. The heat appplitd to the 

 flask should be gradually increased, so as to pioduce a legular, 

 but not too rapid evolution of gas. 



The process having continued thus for ten or twelve hours, may 

 be stopped. The solutions contained in the two bottles are to be 

 mixed together, filtered, and evaporated, so as to yield crystals of 

 hyposulphite of soda. 



The flask will contain sulphate of iron, which may be dissolv- 

 ed out and crystallized. — Ih. from Journ. de Chimie Med. 



DUFLOS' METHOD OF PURIFYING CRUDE HYDRO- 

 CHLORIC ACID. 



MM. Hensler and Riegel have tried this method, and found it 

 to answer well. 



Mix fifteen pounds of crude hydrochloric acid with five pounds 

 of water and one ounce of sulphate of iron; expose the mixture to 

 the air for some time, and when clear pour it into a retort, and 

 distil, at a moderate heat, three-fifths or ihree-fouilhs. 



The product of distillation is clear, colorless, of a proper de- 

 gree of concentration, and quite pure. In the neck of the retort 

 a yellownsh white sublimate will be observed. — lb. from Pharm. 

 Central Blntt. 



