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.