304 Mr. Schweitzer on an Analysis of the 



of sulphuric acid appeared. The fluid thus obtained was 

 evaporated in a water-bath nearly to dryness, and the re- 

 sidue left for twelve hours exposed to the atmospheric air, in 

 order to change the excess of hydrate of barytes into a car- 

 bonate'^. After the separation of the carbonate of barytes the 

 fluid was mixed with sulphuric acid, when S'-ilG grs. of sul- 

 phate of barytes were obtained, equivalent to 1*1220 gr. of 

 nitric acid. 



4. Chlorine. — One-twentieth part, equal to 405 grs. of the 

 fluid containing the soluble ingredients, was evaporated, and 

 the residue fused to destroy the organic matter, and again 

 dissolved. The solution supersaturated with nitric acid was 

 precipitated by nitrate of silver. The precipitate was carefully 

 collected upon a filter and lixiviated, first with water slightly 

 acidulated with nitric acid, and afterwards with pure water. 

 The dried precipitate was heated nearly to the point of fusing 

 in a well-covered porcelain crucible, when 19*388 grs. of chlo- 

 ride of silver were obtained, making for 16 ozs. troy of water 

 38*776 grs.; but, as will be seen hereafter, 0*126 gr. of bro- 

 mide of silver and 0*010 gr. of iodide of silver are to be de- 

 ducted from the amount (38-776 — 0*136), leaving 38*640 grs. 

 of chloride of silver, equivalent to 9*533 grs. chlorine. If we 

 compare the amount of the silver precipitate with that obtained 

 from the preliminary experiment 2, we find a slight difference ; 

 the latter giving from two experiments in 4 ounces 10*053 

 grs., whereas the former, calculated upon the same quan- 

 tity of water, gives 9*694 grs. This discrepancy is accounted 

 for, from the organic matter in the original water being partly 

 thrown down with the silver precipitate. It is therefore re- 

 quisite to free the fluid from its organic matter before the 

 amount of its chlorides can be ascertained. The interference 

 of organic matter with correct results is evidenced by the fol- 

 lowing experiments : — 



a. Four troy ounces of the fresh water gave with nitrate of 

 silver 10*053 grs. 



b. Four troy ounces of the water evaporated with carbonate 

 of soda and freed from the earthy carbonatesf, gave with 

 nitrate of silver 9*883 grs. 



c. Four troy ounces of the water evaporated with carbonate 

 of soda and freed from the earthy carbonates, the filtered liquid 

 again evaporated, the residue fused and again dissolved, gave 

 with nitrate of silver 9*694 grs. 



5. Iodine, — 4860 grs. of the fluid containing the soluble in- 



* It is advisable to evaporate the fluid twice nearly to dryness, and filter 

 each time, and to use for lixiviation as little water as possible, so as to pre- 

 vent the solution of the carbonate of barytes. 



t A portion of the organic matter followed the earthy carbonates. 



