ny other trouble than that of picking it
up. Herbert found a vein of it at the foot of Mount Franklin, and they
had nothing to do but purify this salt.

These different works lasted a week. They were finished before
the transformation of the sulphuret into sulphate of iron had been
accomplished. During the following days the settlers had time to
construct a furnace of bricks of a particular arrangement, to serve for
the distillation of the sulphate or iron when it had been obtained. All
this was finished about the 18th of May, nearly at the time when the
chemical transformation terminated. Gideon Spilett, Herbert, Neb, and
Pencroft, skillfully directed by the engineer, had become most clever
workmen. Before all masters, necessity is the one most listened to, and
who teaches the best.

When the heap of pyrites had been entirely reduced by fire, the result
of the operation, consisting of sulphate of iron, sulphate of alumina,
flint, remains of coal, and cinders was placed in a basinful of water.
They stirred this mixture, let it settle, then decanted it, and obtained
a clear liquid containing in solution sulphate of iron and sulphate of
alumina, the other matters remaining solid, since they are insoluble.
Lastly, this liquid being partly evaporated, crystals of sulphate of
iron were deposited, and the not evaporated liquid, which contained the
sulphate of alumina, was thrown away.

Cyrus Harding had now at his disposal a large quantity of these sulphate
of iron crystals, from which the sulphuric acid had to be extracted. The
making of sulphuric acid is a very expensive manufacture. Considerable
works are necessary--a special set of tools, an apparatus of
platina, leaden chambers, unassailable by the acid, and in which the
transformation is performed, etc. The engineer had none of these at his
disposal, but he knew that, in Bohemia especially, sulphuric acid is
manufactured by very simple means, which have also the advantage of
producing it to a superior degree of concentration. It is thus that the
acid known under the name of Nordhausen acid is made.

To obtain sulphuric acid, Cyrus Harding had only one operation to make,
to calcine the sulphate of iron crystals in a closed vase, so that the
sulphuric acid should distil in vapor, which vapor, by condensation,
would produce the acid.

The crystals were placed in pots, and the heat from the furnace would
distil the sulphuric acid. The operation was successfully complet