7 
Gooch and Fairbanks—FHalogens in Mixed Silver Salts. 2 
Art. IlI.—TZhe Estimation of the Halogens in Mixed Silver 
Salts; by F. A. GoocH and CHARLOTTE FAIRBANKS. 
[Contributions from the Kent Chemical Laboratory of Yale College—XX XIX. ] 
KNowN methods for the estimation of chlorine, bromine, and 
iodine in mixed silver salts depend either upon the reduction 
of the salts to metallic silver or their conversion to a single 
definite silver salt. The old but by no means ideal methods 
for the determination of chlorine and bromine in mixed silver 
chloride and bromide by reduction of the salts to silver in 
hydrogen at high temperatures or conversion to silver chloride 
in an atmosphere of chlorine are typical. Perhaps the best of 
all are the electrolytic method of Kinnicutt* for the reduction 
of the fused chloride and bromide, the battery process of 
Whitfield+ which involves the electrolysis of the solution of the 
silver salts in potassium cyanide and the method of Maxwell- 
Lytet according to which the silver in the cyanide solution of 
the silver salts is thrown down by potassium iodide and sul- 
phuric acid. Even in these processes there are points against 
which objection may be raised with reason. Thus, in the 
processes of Whitfield and Maxwell—Lyte it is next to impos- 
sible to secure complete and speedy solution of the dried silver 
salts in potassium cyanide without recourse to intermediate 
washing and treatment with nitric acid; and in Kinnicutt’s 
method, which has been applied only to the analysis of the 
mixed chloride and bromide, difficulty is found in the speedy 
removal of all sulphuric acid from the spongy mass of silver 
formed in the reduction. 
We have tried many experiments with a view to simplifying 
the analysis of the mixed silver salts. Ignition with mercuric 
eyanide according to Schmidt’s method for sulphides;$ treat- 
ment with cuprous chloride dissolved either in ammonia or in 
hydrochloric acid; the action of ferrous oxalate dissolved in 
potassium oxalate, Eder’s reagent;| treatment with chromous 
chloride or chromous acetate; contact with powdered mag- 
nesium under dilute acid; and many other plans of action 
with powerful reducers have failed to yield analytical results 
comparable with those of the known methods. Hydrogen 
sulphide, dry or moist, and ammonium sulphide attack the 
halogen salts of silver with varying intensity, the chloride very 
* Am. Chem. Jour., iv, 22. + Am. Chem. Jour., viii, 421. 
t Chem. News, xlix, 3. S Ber. d. chem. Gesell., xxvii, 225. 
|| Ber. d. chem, Gesell., xiii, 500. 
