CHAP. VII.Of the Methods of preventing Accidents.
Tohave informed the Reader of the Accidents which happen in Distilling, would have been of little Consequence, without shewing, at the same Time, the Methods of preventing them. In order therefore to fortify him against the Terror, which the foregoing Chapter may have excited, we will here point out the Remedies for all the Cases before specified.
To prevent Accidents, two Things especially must be known, and adverted to.
1. The Knowledge of the Fire, which depends on the Fuel, whether Wood or Coal.
2. The Manner of luting so as to prevent the Vapours from escaping through it, and by that Means of setting the whole on fire.
The hardest Wood generally makes the quickest Fire, such as Beech, Oak, Holm, Elm,&c.The white Woods, as the Ash, the Poplar, the Willow, and the Birch, make a milder Fire. This holds good also of the Coal made of these two kinds of Wood; and, consequently, the Nature of the Wood or Coals must determine the Fire, and the Action of this must be proportioned to the Effect intended to be produced by it. That is, the Capacity of the Alembic, the Matters to be distilled, and their Quantity. The same may also be said of Pit Coal, which is generally used inEngland.
It is evident, that the larger the Alembic, the more Fire is necessary. What has not been digested, also, requires more Fire than that which has been prepared by that Operation. Spices require a stronger Fire than Flowers; a Distillation of Simple Waters more than that of spirituous Liquors.
The surest Way of ascertaining the necessary Degree of Fire, is to regulate it by the Materials, as they are more or less disposed to yield them Spirits,&c.and this is done as follows. The Operator must not leave the Alembic, but attentively listen to what passes within, when the Fire begins to heat it. When the Ebulition becomes too vehement, the Fire must be lessened, either by taking out some of the Fuel, or covering it with Ashes or Sand.
It requires a long Experience in the several Cases, before a Distiller can acquire a competent Knowledge in this important Point. Nor is it possible to determine the Degree of Fire from the Quantity of Fuel; Judgment, assisted by Experience, must supply this Defect.
Every thing being determined with regard to the Degree of Fire, we shall now proceed to explain the Method of luting Alembics.
By the Term luting an Alembic, we mean, the closing the Joints through which the Spirits might transpire.
Lute is a Composition of common Ashes, well sifted, and soaked in Water; Clay, and a kind of Paste made of Meal or Starch are also used for this Purpose; which, as I before observed, is to close all the Joints,&c.in order to confine the Spirits from transpiring.
Good Luting is one of the surest Methods of preventing Accidents. An Alembic,where all Transpiration is prevented, having nothing to fear but the too great Fierceness of the Fire; and that may be regulated by the Rules already laid down.
The refrigerating Alembic is mostly used. The Body and the Head are joined to each other; but notwithstanding the greatest Care be taken in luting the Juncture, there will still be some imperceptable Interstice for Transpiration; and the least being of the greatest Consequence, a Piece of strong Paper, should be pasted over the Joint, and the Alembic never left, till the Spirits begin to flow into the Receiver, in order to apply fresh Paper, if the former should contract any Moisture. The Master himself should carefully attend to this, and whatever Precaution may have been previously used, the Eye must be constantly upon it.
The Alembic, when vinous Spirits are distilled, should be luted with Clay, carefully spread round the Junctures, in order to prevent all Transpiration; because the Consequences here are terrible; for when the Fire catches a large Quantity, it is often irremediable. Besides, as this Earth cracks in drying, it must be often moistened, and fresh applied, on the first Appearance of any Occasion for it.
The Retort is also luted with Clay; but as glass Retorts are also used, they are often coated with the same Clay, to prevent their melting by the Intenseness of the Fire.
Lastly, the earthen and glass Alembics are luted with Paper and Paste as above.——Having thus explained the great Consequence of Circumspection with regard to Luting, and the Degree of Fire, we shall now proceed to a third Method of preventing them, and close this Chapter with a short Observation on portable Furnaces; which is, That Alembics being never thoroughly secure on this kind of Furnaces, a Hook should be fastened to the Refrigerant for fixing it to the Wall.