196 F. Hi. Storer on Nitric Acid and Chlorate of 
sium, In ge eneral, however, the coloration of the liquor in the 
be a sufficient indication that the copperas has done its work. 
The nitrous fumes quickly disappear from the liquid at a sub- 
creer. stage of operations when metallic iron is immersed in 
the solu 
When initia of the ferrous sulphate has been added, filter 
the mixed solution into a wide beaker, precipitate the copper, 
in the metallic state, upon a sheet of iron in the usual way 
and ignite the copper in a porelain crucible, in a current of 
hydrogen, re weighing 1 
By means of the eibipa' salt the last traces of nitric acid 
may be got rid of far more quickly, conveniently and certainly 
than by the old system of evaporating the pyrites solution with 
several successive portions of chlorhydric acid. By treating 
the pyrites with chlorate of potassium and nitric acid it is easy 
to oxydize and dissolve every particle of the sulphur in the 
mineral so that no portion of the latter can escape decomposi- 
tion by becoming ee gt in free sulphur, When aqua regia is 
used on the other hand, or a mixture of chlorate of i. 
and chlorhydric acid, a arti proportion of sulphur almost 
invariably remains undissolved and might easily siistiah por- 
tions of the mineral so as to protect them from the solvent 
action of the acids. 
The method of oxydation above described can manifestly be 
employed with advantage for one’ many other sulphu- 
retted ores besides copper pyrite 
January, 1869. 
Estimation of Sulphur in Sulphid of Mercury ; by E. W. 
Bowpitcu. 
In order to contrast the action of the mixed ee age - 
acid as the ¢ case ase wane he a a into the flask, a sma 
mrad of chlorate of potassium as added and the ‘mixture 
