a POT wetter s - 
ON ELECTROLYTIC METHODS OF QUANTITATIVE ANALYSIS. 255 
Although accurate results can be obtained by electrolysing an ammonium 
tartrate solution of an antimony salt the method requires much greater 
attention and the conditions are more limited than the above; it is, there- 
fore, not to be recommended from a practical standpoint, whereas the 
deposition from a solution of the sulpho-salt possesses advantages over the 
ordinary gravimetric methods for the determination of antimony both in 
regard to rapidity and accuracy. 
The Determination of Tin. By Cuarues A. Kony, Ph.D., B.Sc., and 
C. K. Barnes, B.Se. 
Libliography. 
Author Journal Year} Vol. | Page Composition of Electrolyte 
Luckow,C.. . «.  . | Zeits. anal. Chem. | 1880] 19 1 | { Hydrochloric acid. 
| Alkali sulphide. 
Classen, A., and Ieis, M.A. |Ber, . . «| 1881] 14 | 1692 Vinee 
Classen, A. . - aie =| eBeren : -| 1884} 17 | 2467 | Ammonium sulphide. 
Moore,T. . 3 . | Chem. News -| 1886 | 53 209 | Phosphoric acid. 
Riidorff, F. . : . | Zeitsangew.Chem.} 1892 | — 197 | Acid ammonium oxalate, 
Freudenberg, H. . : . | Zeits. phys. Chem. | 1893 | 12 97 | Ammonium oxalate. 
( Acid ammonium oxalate. 
Classen, A. . * - «t| Berrw « . -| 1894 | 27 | 2060 lac oxalate and acetic 
acid. 
Thomiilen,H. .« . ~~ | Zeits. Electrochem) 1894 1 304 | Acid ammonium oxalate, 
| ( Hydroxylamine sulphate. 
Engels,C. «2 «  - Zeits, Electrochem| 1896 | 2 | 413 |4A™mmonium acctate, tartaric 
( acid and Hydroxylamine 
hydrochloride. 
— 
Luckow states that tin can be deposited from a hydrochloric acid 
solution, or from a solution of the sulphide in alkali sulphide ; but no 
analytical data are given in his paper. According to Classen and Reis 
(Ber., 1881, 14, 1622) fair results are obtained by using a hydrochloric 
acid solution; but the most important methods are those in which an 
ammonium oxalate or an alkali sulphide solution are employed. The 
experimental work has therefore been confined to these methods. Moore 
states that tin is easily deposited from an acid or alkaline solution of the 
metal in glacial phosphoric acid, but gives no details or experimental 
data ; the method has not been tried. 
The Deposition of Tin from an Ammonium Oxalate Solution. 
The separation of stannic acid during the electrolysis of ammonium oxa- 
late solutions of tin salts, owing to the solution becoming alkaline, renders 
it necessary to keep the solution acid during the electrolysis. Classen uses 
either oxalic acid or acetic acid for this purpose ; in both cases a CD. inc 
of 03 ampere is employed, which is increased to 0-5 or even 1-0 ampere 
towards the end of the experiment. 0-3 grme. of metal are deposited in 
from 6 to 9 hours, according to the strength of the current. Freudenberg 
has found that in an E.M.F. of 2:3 to 2-7 volts is required to separate tin 
from an oxalate solution. 
A large number of experiments were made with ammonium oxalate 
solutions, under varying conditions, typical results of which are recorded. 
The method was not found to be reliable. It is very dificult to effect 
the complete deposition of the tin before the solution becomes alkaline 
unless a large excess of acid is employed, and this very much retards 
the rate of deposition, An increase in current density might overcome 
