There
results a hot, neutral, concentrated solution of copper sulphate,
which may be run at once into a crystallizing vat for the separation
of commercial crystals of copper sulphate. It will be readily
understood, of course, that if there should be any advantage in
manufacturing that commercial article, besides the amount prepared as
described, which represents merely the copper contained in the
bullion, copper sheets may be regularly employed for reducing the
silver sulphate in D. The author trusts that the practical refiner
will recognize that the manufacture of commercial copper sulphate is
thus effected in a more rational and economical manner than by the
present method of evaporating from 25 deg. B. to 35 deg. B., and of saturating
by oxidized copper, generally in a very incomplete manner, the large
amount of free acid left from the refining by the usual process.
However, the sale of copper sulphate is but rarely so profitable that
a refinery should not gladly dispense with that troublesome and bulky
manufacture, especially the government establishments, which, besides,
waste much valuable space with the crystallizing vats.
The great saving in sulphuric acid, amounting to about 50 per cent.
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