to cover the powdered fluor spar. Let every thing remain in this state for
three hours; then remove the mixture, and clean the glass, by washing it
with oil of turpentine; the figures which were traced through the wax will
be found engraven on the glass, while the parts which the wax covered will
be uncorroded. The fluate of lime is decomposed by the sulphuric acid, and
sulphate of lime is formed. The fluoric acid, disengaged in the gaseous
state, combines with the water that diluted the sulphuric acid, and forms
liquid fluoric acid, by which the glass is corroded.


_Habits of Seals._

The brain of this animal, observes Dr. Harwood, is I think, doubtless, of
greater proportionate magnitude than in any other quadruped, and not only
does it exhibit in its countenance, the appearance of sagacity, but its
intelligence is in reality far greater than in most land quadrupeds: hence
its domestication is rendered much easier than that of other animals, and
it is susceptible of more powerful attachment. The large seal, which was
exhibited some time ago at Exeter 'Change, appeared to me to understand
the language of its keeper as perfectly as the most faithful dog. When he
entered at one end of its long apartment, it raised its body from the
water, in which it was injudiciously too constantly kept, supporting itself
erect against the bar of its enclosure, and wherever he moved, keeping its
large, dark eyes steadfastly fixed upon him. When desired to make obeisance
to visitors, it quickly threw itself on one side, and struck the opposite
one several times in quick succession with its fore-foot, producing a loud
noise. The young seal, again, which was kept on board the Alexander, in one
of the northern expeditions, became so much attached to its new mode of
life, that after being thrown into the sea, and it had become tired of
swimming at liberty, it regularly returned to the side of the beat, to be