298 Prof. H. Rose on the separation of Tin from other Metals. 
oxidized with nitric acid in the usual manner, and the residue 
digested with moderately strong hydrochloric acid. On the 
addition of a large quantity of water, all is dissolved, and the tin 
is then precipitated with sulphuric acid. 
In the separation of copper and tin by the ordinary method, 
the binoxide always contains a trace of copper; but by the above 
process the separation of the two metals is complete, the binoxide 
is quite free from copper. 
Tin and lead are best separated by fusing the alloy with 
sulphur and carbonate of potash. On treating the mass with 
water, the sulphide of tin dissolves. This is the best method of 
analysing the fusible alloy of tin, bismuth, and lead. Tin and 
silver are also best separated in this way. 
In an acid solution, tin and bismuth are best separated by 
sulphide of ammonium. 
The separation of iron from tin can only be completely effected 
by oxidizing the alloy with nitric acid, dissolving in hydrochloric 
acid, and saturating the hydrochloric solution with sulphuretted 
hydrogen. 
Tin is best separated from titanium by means of sulphide of 
ammonium. 
The separation of the oxides of tin from magnesia and the 
alkaline earths is best effected by igniting them with sal- 
ammoniac, by which the tin escapes as chloride. In general all 
the tin is expelled by one ignition; but two are always amply 
sufficient to remove the last traces of tin. 
In the analysis of minerals, the separation and estimation of 
tin is best effected by converting it ito the oxide. The volu- 
metric analysis, however, is very convenient for the determina- 
tion of the tin in tin-salts. The ordinary method is to convert 
the protochloride of tin in hydrochloric acid solution into the 
bichloride by means of oxidizing agents, such as permanganate 
or bichromate of potash. But protochloride of tin absorbs atmo- 
spheric oxygen, even during the determination, to such an extent 
as materially to vitiate the results of analyses. 
Stromeyer* has observed that good results are obtained by 
the addition of sesquichloride of iron im excess to the freshly 
prepared solution of tinin hydrochloric acid. The reaction is as 
follows :— 
Sn Cl-+ Fe? Cl? =Sn Cl? +2 Fe Cl. 
The protochloride of iron formed is determined by permanga- 
nate; and as it is not nearly so susceptible to atmospheric 
oxygen as protochloride of tin, much more accurate results are 
obtained. 
* Liebig’s Annalen, February 1861. 
