ON ELECTROLYTIC METHODS OF QUANTITATIVE ANALYSIS. 259 
but, from an analytical standpoint, the method possesses no advantages 
over that described in Series II and III. 
Series V. 
Ammonium Sulphide Solution. 
Luckow and Classen (/oc. cit.) have both suggested the deposition of 
tin from a solution of a sulpho-salt, and the latter records a number of 
accurate results obtained by employing the ammonium sulpho-salt. The 
following experiments show that the method is reliable and rapid. The tin 
solution, prepared in the manner previously described, was neutralised 
with ammonium hydrate, and sufficient pure ammonium sulphide added 
to form the sulpho-salt, the whole being then diluted to 175 c.c. before 
being electrolysed. 
Experi- Tin taken : Tin found : C. D. 400 E.M.F. Time: 
ment Grme. Grme. Amperes Volts hours 
1 0°1026 0:1032 118 73 53 
2 0°1026 071026 119 77 52 
3 0:1026 0:1035 1:25 76 52 
4 0:0513 0:0510 1:16 73 43 
5 0:0206 ' 0:0207 0:96 V1 43 
6 0:0103 00102 0°85 8-1 4} 
The above were six consecutive experiments. In addition to being 
vapid the method is reliable, and requires no supervision. The deposit is 
dark in colour, but adheres well to the dish, and does not oxidise at all 
during the drying. Under the above conditions no deposit of sulphur on 
the cathode, as has been referred to by others, occurred ; provided the 
ammonium sulphide is carefully prepared this can be quite avoided. 
Summary. 
The electrolytic deposition of tin from the solution of its ammonium 
sulpho-salt is a convenient and accurate method for the quantitative esti- 
‘Mmation of the metal. The double oxalate solution, acidified either with 
oxalic acid or with acetic acid, can, when carefully worked, be made to 
yield very fair results, but it cannot be regarded as reliable ; and, as an 
analytical method, it is inferior in accuracy, rapidity, and convenience to 
‘the electrolysis of the sulpho-salt solution, this latter being especially 
handy, as it deals directly with the sulphide of tin, the form in which 
the metal is always obtained in analysis when not separated as oxide. 
The addition of a hydroxylamine salt to the oxalate solution certainly 
renders the method easier to carry out, but it does not obviate the other 
defects mentioned. 
The Electrolytic Separation of Antimony from Tin. 
By Cuartes A. Koun, Pi.D., B.Sc., and C. K. Barnes, B.Sc. 
Bibliography. 
en AE sar — 
5 Metals | 
Author Journal | Year! Vol. | Page | separated | Composition of Electrolyte 
from 
Classen, A,, and Ludwig, R.| Ber. .] 1885 | 18 | 1104 As, Sn Sodium sulphide and hydrate 
Classen, A., and Ludwig, R. | Ber. . | 188 | 19 323 | As,Sn | Sodium sulphide and hydrate 
Classen, A.,and Schelle,R. | Ber. .| 1988 | 21 | 9892] Sn Sodium sulphide and hydrate 
Olassen,A. . 6 866) 4) Bers =. | 1994 | 27 | 2060 As,Sn | Sodium sulphide and hydrate 
82 
