1librae of the latter.
Shortly afterward the solution will be found to be clear
and blue. It is boiled until the waters, which are easily volatile (subtiles), are
evaporated, and then the greater part of the salt, after it has settled at the
bottom of the pan, is taken out with iron ladles. Then the concentrated
solution is transferred to the vat in which rods are placed horizontally and
vertically, to which it adheres when cold, and if there be much, it is condensed
in three or four days into saltpetre. Then the solution which has not con
gealed, is poured out and put on one side or re-boiled. The saltpetre being
cut out and washed with its own solution, is thrown on to boards that it may
drain and dry. The yield of saltpetre will be much or little in proportion
to whether the solution has absorbed much or little; when the saltpetre
has been obtained from lye, which purifies itself, it is somewhat clear and
pure.
and blue. It is boiled until the waters, which are easily volatile (subtiles), are
evaporated, and then the greater part of the salt, after it has settled at the
bottom of the pan, is taken out with iron ladles. Then the concentrated
solution is transferred to the vat in which rods are placed horizontally and
vertically, to which it adheres when cold, and if there be much, it is condensed
in three or four days into saltpetre. Then the solution which has not con
gealed, is poured out and put on one side or re-boiled. The saltpetre being
cut out and washed with its own solution, is thrown on to boards that it may
drain and dry. The yield of saltpetre will be much or little in proportion
to whether the solution has absorbed much or little; when the saltpetre
has been obtained from lye, which purifies itself, it is somewhat clear and
pure.
The purest and most transparent, because free from salt, is made if it is
drawn off at the thickening stage, according to the following method. There
drawn off at the thickening stage, according to the following method. There
A—CALDRON. B—LARGE VAT INTO WHICH SAND IS THROWN. C—PLUG.
D—TUB.
E—VAT CONTAINING THE RODS.
E—VAT CONTAINING THE RODS.
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