Intelligence and Miscellaneous Articles. 81 
correct, yet it may be advantageously superseded by passing a current 
of sulphuretted hydrogen gas through the solution of the mixed metals 
made strongly acid, separating the bisulphuret of copper, and after 
heating the solution to expel the excess of sulphuretted hydrogen, the 
zinc may be precipitated by carbonate of soda. Another experiment, 
in which the process recommended by Mr. Phillips for separating oxide 
of cobalt from oxide of nickel by adding a solution of potash to an 
ammoniacal one of the mixed metals, was tried with equally unsa- 
tisfactory results, for from 20 grains of zinc and 30 grains of oxide 
of nickel a precipitate was thrown down from an ammoniacal solution 
by potash, weighing after ignition 48 grains, giving 18 grains of oxide 
of zinc mixed with 30 grains of oxide of nickel. 
After many other methods, of which it will suffice to say that they were 
all unsuccessful, I was led to try the effect of sulphuretted hydrogen 
gas upon the salts of nickel and zinc, when solutions of them, pre- 
viously neutral, are acidified by oneof the weaker acids, and which 
acid should likewise form soluble salts with both metals. Pursuing 
this idea, | mixed a little acetic acid with a neutral solution of zinc, 
and also with a neutral solution of nickel, and passed a current of 
sulphuretted hydrogen through both the solutions: in the solution of 
nickel no precipitation took place, but in that of zinc an abundant 
white precipitate fell ; and by passing excess of the gas through the 
solution, the whole of the zinc was precipitated as a sulphuret. I 
then made an experiment to determine whether it was possible to 
analyse German silver by passing sulphuretted hydrogen through its 
solution, differing in its acidity, both as regards the acid and degree 
of acidity at different times, according to the nature of theg precipi- 
tate desired, whether copper or zinc ; the results obtained were very 
satisfactory, 
245 grains of copper, 12 grains of zinc, and 20 grains of oxide of 
nickel were dissolved in nitromuriatic acid; the solution, strongly 
acidified with muriatic acid, was diluted with about a pint of water; 
a current of sulphuretted hydrogen gas was then passed through the 
Solution until all the copper was precipitated; the bisulphuret of 
copper formed having been well washed, was acted on by nitric acid, 
which dissolved the copper and left some sulphur ; after the separa- 
tion of the latter, the solution of copper was boiled with caustic soda 
to precipitate the peroxide, which after ignition weighed 30°4=24:3 
grains of copper. The solution containing the zinc and nickel was 
carefully evaporated to dryness, to expel the excess of acid, and the 
residue dissolved in water acidulated with one fluid ounce of strong 
acetic acid sp. gr. 1:0691, and warmed to assist the action : when this 
was effected, the solution was diluted to about a pint, and a stream 
of sulphuretted hydrogen gas was passed through it until the gas was 
in excess ; a dingy white precipitate of sulphuret of zinc fell, which 
weighed 18 grains = 12 grains of metallic zinc. 
The remaining solution containing the nickel, after being heated 
to expel the sulphuretted hydrogen, was decomposed by caustic soda ; 
this gave hydrate of nickel, which when reduced to protoxide by strong 
ignition, weighed 20°1 grains. In this experiment there was a loss 
Third Series. Vol. 8. No. 43. Jan. 1836. M 
