Such bitumens or resins, as spirit of wine will not touch, are dissolved in oils by means of fire, and then form another kind of Varnish, which water does not hurt. These Varnishes are usually coloured, and require much longer time to dry than the Spirit Varnishes: they are called _Oil Varnishes_. Spirit of wine hath a much greater affinity with water than with oily matters: and therefore if a solution of any oil or resin in spirit of wine be mixed with water, the liquor immediately grows turbid, and acquires a whitish milky colour, owing entirely to the oily parts being separated from the spirituous menstruum by the accession of water, and too finely divided to appear in their natural form. But if the liquor stand some time quiet, several of these particles unite together, and gradually acquire a bulk sufficient to render them very perceptible to the eye. Acids have an affinity with spirit of wine, and may be combined with it. By this union they lose most of their acidity, and on that account are said to be _Dulcified_. But as these combinations of acids, especially of the vitriolic acid, with spirit of wine furnish some new productions of very singular properties, and as an examination thereof may throw much light on the nature of ardent spirits, it will not be amiss to take notice of them in this place, and consider each of them particularly. One part of highly concentrated oil of vitriol being mixed with four parts of well dephlegmated spirit of wine, there arises immediately a considerable ebullition and effervescence, attended with great heat, and abundance of vapours, which smell pleasantly, but are hurtful to the lungs. At the same time is heard a hissing like that produced by a piece of red-hot iron plunged into water. Indeed it is proper to mix the liquors very gradually; for otherwise the vessels in which the operation is performed will be in great danger of breaking. If the two liquors thus mixed be distilled with a very gentle heat, there rises first a spirit of wine of a most penetrating and grateful odour: when about half thereof is come over, what follows has a quicker and more sulphureous smell, and is also more loaded with phlegm. When the liquor begins to boil a little, there comes off a phlegm which smells very strong of sulphur, and grows gradually more acid. On this phlegm floats a small quantity of a very light and very limpid oil. In the still there remains a thick blackish substance, somewhat like a resin or bitumen. From this substance may be separated a good deal of a vitriolic but sulphureous acid. When that is extracted, there remains a black mass like a charred coal, which being put into a crucible, and exposed to a violent heat, leaves a small portion of earth, very fixed, and even vitrifiable.