The Refrigerant is so essential a Part of the Alembic, that for want of it several other Expedients are made use of to perform its Office, for cooling those whose Capacity, Brittleness, or lastly the Construction, will not admit of their having any.

The Refrigerant is usually in proportion to the Capacity of the Alembic, for which the following may serve as a Rule, that the Capacity of the Refrigerant should be to that of the Alembic, as 14 to 8.

The Necessity of cooling the Head of the Alembic is self-evident to all who have the least Knowledge of Distillation, as it condenses the Spirits, cools them, and causes them to flow into the Receiver, which, if of Glass, would otherwise be broken by the Heat; and consequently serves to prevent Conflagrations.

The Alembics of the Balneum Mariæ, and the Vapour Bath, ought also to have Refrigerants, like the common Alembic, unless they are of Glass.

Those of Earth and Glass are cooled, as we have already observed, with a wet Cloth, which is also used to cool the Head of other kinds of Alembics. But it is not difficult to contrive one which may be placed in a Refrigerant; such as the following.

To a common small Still apply and lute a Worm, or long tin or pewter Tube, forming several Circumvolutions, of the same Circumference with the Body, in order to give it some Elevation, place this Worm in a Refrigerant, proportioned to the Alembic. If the Capacity of this Alembic should make it bear too much on the Neck of the Matrass, it may be supported by a Trevit of the same Circumference as the Body itself: The Extremity of the Worm may have a Beak projecting beyond the Side of the Refrigerant, for conveying the Spirits into the Receiver.

This Apparatus will be attended with little Expence, will save the Distiller the Trouble of being perpetually cooling the Head of the Alembic, and is such a Safe-guard against Accidents, that if the Worm be well luted, nothing need be apprehended but from the Violence of the Fire.

This Method of Practice, therefore, is productive of three valuable Particulars: The first is, that by cooling the Spirits it preserves the Receiver, and obviates the Accidents arising from their Heat. The second is, that the Spirits being kept in a moderate Heat, the Transpiration is less, and consequently the Spirits procured by the Operation have more Taste, Smell and Fragrancy than they would otherwise have had.

Experience demonstrates, that when the Spirits flow hot into the Receiver, however attentive the Distiller may be to lute the Junctures of the Alembic, there will be a very sensible Evaporation, which even in simple Waters greatly depreciates the Goodness of the Liquor.

Lastly, the third is, that the Cooling of Alembics is what principally contributes to the Perfection of the Operation; because the Coolness of the Head precipitates the Phlegm, and in the Case of too great a Degree of Fire, and where the Ebullition is too vehement, if after taking away Part of the Fire, or covering it, the Ebullition should continue, the Head may be cooled with a wet Cloth, till the Ebullition is reduced.

As there is a Necessity of cooling the Alembic, so what we have said cannot be too carefully observed. In fine, the Contrast of Cold and Heat, equally concurring, but by Methods directly opposite, to the same Process, and the Perfection of the Distillation, is a Phœnomenon, which deserves the Attention of all who study the Operations of Nature.