128 Mr. Denham Smith on the Composition of 



few drops of the solution, gave no precipitate, or but a faint 

 trace of one. The insoluble i*esidue was dried at 212°, its weight 

 was noted, and the aqueous solution, which usually amounted 

 to about a pint and a half, was accurately measured, and its 

 quantity made up to exactly 32 or 40 fluid ozs. This solu- 

 tion, when freshly prepared, was generally neutral or slightly 

 acid ; in no one instance have I found it alkaline, but it became 

 so when kept in a stopped bottle for some days. 



One-sixth or one-eighth of this solution acidified with nitric 

 acid and treated with nitrate of silver gave ihe amount of chlo- 

 rine — hydrochloric acid. The same quantity similarly treated, 

 but with barytes instead of silver, indicated the quantity of 

 sulphuric acid. 



Another portion, slightly acidified with acetic acid (a few 

 drops are sufficient), and treated with hydrochlorate of lime, 

 gave, if any oxalic acid were present, the amount of that acid, 

 the precipitate of course being treated in the usual way ; to 

 this filtered solution, having previously boiled it and taken 

 care that an excess of lime salt was present, was added excess 

 of ammonia, which precipitated the phosphoric acid as bone- 

 phosphate; this result was corrected by the weight of phos- 

 phate of silver obtained during a subsequent operation. 



The quantity of ammonia was determined by distilling one- 

 fourth or one-sixth of the solution in the mode described in a 

 foregoing part of this paper. 



If poiash and soda were both found to exist in the solution 

 by previous experiment, the following operation was carried 

 completely out ; if one only of these alkalies were present, the 

 process was discontinued when the weight of the alkaline sul- 

 phate had been determined. One-fourth at least of the solu- 

 tion was gently evaporated, by which it became markedly acid ; 

 this evaporation was carried to dryness till no more water was 

 given off, taking care to avoid volatilization of any salt of am- 

 monia, although uncombined ammonia had been liberated 

 during the evaporation ; when quite dry it was confined for a few 

 hours over a mixture of powdered lime and sal-ammoniac, then 

 the vessel containing the residue of the evaporated solution 

 was gently warmed and weighed ; this afforded the quantity 

 of solid matter contained in the cold aqueous solution, together 

 with traces of water combined with salts and organic matter. 

 This residue was then ignited, the organic matter and am- 

 moniacal salts were expelled, and the loss, deducting from it 

 the weight of the salts of ammonia, was estimated as organic 

 matter with a little water ; the fused residue was dissolved in 

 water and precipitated by nitrate of silver; this precipitate, when 

 collected, fused and weighed, and the fused salt of silver treated 



