In the third Chapter we mentioned the several kinds of Distillation, we shall here enlarge on the particular Advantages of each, and in what Circumstances each is to be used.

In order for Distillation, the Alembic must be charged with Materials, and placed on a Fire, or Substances capable of producing the same Effect.

The Method of Distilling with the common refrigerant Alembic.

This Method of Distilling is the most generally used, being one of the most speedy and profitable, as it requires fewer Preparatives, and less Time.

To distil with the common Alembic, the Body of it must be thoroughly cleansed, that no Taste or Smell of any preceding Materials may remain. The Materials are then to be put into the Alembic; but care must be taken that the Alembic be not above half full, in order that the Materials may have sufficient Room to move, without choaking the Neck of the Alembic. The same Care must be taken with regard to the Head, it must be thoroughly cleansed and dried; for it often happens that some small Quantity of Water is left in the Rim, which renders the first Spirits foul, and, by endeavouring to separate it from the other, some, and that the most volatile Part of the Spirit, will be lost.

After this the two Parts of the Alembic are to be carefully luted with strong brown Paper, well pasted on, and the Nose of the Alembic luted to the Worm; after which the Fire should be immediately made under the Still, lest too long an Infusion should prejudice the Liquor.

This Alembic being worked on an open Fire, the Operation is quicker than any other; but the Degree of Fire requires a very close Attention; as a different Management is necessary to different Materials. The Water of the Refrigeratory must be changed from time to time, and if the Case requires it, the whole Head, but especially the Bec, must be kept cold.

Of Distillation in Sand, and in what Cases it should be used.

This Species of Distillation is performed in two different Manners. First, by covering the Fire with Sand or Ashes, and placing the Alembic upon it. This Method is very necessary in Digestion, and for the perfect Rectification of Spirits. Sand is absolutely necessary for moderating the Action of the Fire, when there is Reason to fear the Matter contained in the Bottom of the Alembic will burn.

The second Method of Sand Distillation, is to take the finest River Sand, and after thoroughly washing it, put into the Alembic a Quantity sufficient to cover it three Fingers deep; after which the Still is to be charged with the Ingredients to be distilled. This serves instead of Water in certain Cases, where the Use of it would prejudice the Ingredients; as in the fine spirituous Waters impregnated with the aromatic Parts of Flowers; the Sand preventing the Ingredients from burning. It is also necessary in distilling rectified Spirits from Seeds.

This Operation being finished, the Alembic must be thoroughly cleansed from the Sand, that the Taste or Smell contained therein, be not communicated to any other Charge of different Ingredients.

Of Distilling in Balneum Mariæ, and its Advantages.

This Method of Distillation is of great Use in several Cases. Its Operation is more perfect, and is subject to few, if any of those Accidents attending Distillations on an open Fire.

In distilling sweet-scented Waters from Flowers, aromatic Plants, and others of that kind, where neither Water, nor Spirit ought to be mixed with them, there is an absolute Necessity for using the Balneum Mariæ; as by every other Distillation, on an open Fire, the Ingredients would infallibly burn.

If Sand should be made use of, the Fire would melt the Tin from the Alembic, and the Contents be in the utmost Danger of being burnt.

In distilling in Balneum Mariæ, a glass Alembic is generally used. This Alembic is to be placed in a Copper Vessel filled with Water. This Vessel ought at least to be of half the Height of the Alembic: at the Bottom of the Copper Vessel must be a Trivet on which the Alembic is to be placed, that it may not touch the Bottom of the Copper, because when the Water begins to boil, it disperses itself towards the Sides, and leaving the Bottom dry, the Ingredients would be in danger of burning.

The Use of the Balneum Mariæ is excellent for those Ingredients which require little Spirit; but if a Copper Alembic be used, be sure to place Sand at the Bottom, that the distilled Liquor may not contract any ill Taste or Smell. This Method is also adviseable in the Rectification of Spirits, on Account of the Danger attending this Operation when performed on a naked Fire.

Were this Method of Distillation as expeditious as that performed on a naked Fire, no other ought to be used, because it is subject to no Accidents, and at the same Time the Spirit, &c. distilled is much more fragrant and grateful.

In the Chapter relating to Accidents, we have mentioned the earthen Alembic; we must now add, that it ought never to be used, except the Matter to be distilled have a strong and bad Smell, and then seldom above once, unless it be for Ingredients of the same or similar Qualities.

This Alembic being very difficult to be managed, we can only recommend it in the Case above-mentioned.

As a naked Fire is generally applied to this Alembic, it requires a Furnace where the Fire may be gradually increased, on account of the Accidents to which it is liable.

The glass Alembic is more easily managed, as it is generally placed in a Balneum Mariæ. Its principal Use is for distilling Waters from Flowers, and making Quintessences; and were it not for the Length of the Operation, it would be preferable to any other Method.

This Alembic hardly admitting of a Refrigerant, a wet linen Cloth must be placed on the Head, and often changed.

The Receiver of this Alembic must not be very large, because of the Fragility of the Bec; but if it were ever so little bent into a Curve, the Largeness of the Receiver would be of no Prejudice; because then its whole Weight would be supported by its Stand.

Advantages of Distillation performed by the Vapour Bath.

This Method differs very little from the Balneum Mariæ, and is used nearly in the same Circumstances; but has greatly the Advantage of the Balneum Mariæ in the Quickness of the Operation. And Lemery, in the first Part of his Course of Chemistry, affirms its Operation to be more perfect.

However that be, its Use is equal to that of the Balneum Mariæ; but in distilling sweet-scented Waters, or Flowers, Sand must be placed at the Bottom, that the Liquor may not contract a Taste from the Copper.

Cases where Dung, Husks of Grapes, and Lime, are to be used.

These Substances are rarely used except in Digestions; and therefore of no great Use to Distillers, they using only hot Ashes, or a Fire well covered for that Purpose.

If Dung be used it must be of the hottest kind, viz. that of the Horse or Sheep, and the Quantity proportioned to the Heat intended. The Lime must be quick; and if the Heat required be moderate, Lime which has lain some time in the Air must be used. The same is to be observed with regard to the Husks of Grapes. But in whatever manner these are used, the Digestions must be performed in a close covered Vessel.