For distillation, this aromatic paste is, at any season, to be put into the body of the still with twice its weight of water; and when heat is applied, the oil, or essential water, is to be obtained in the common way. Both the oil and water are in this way produced in greater quantity than by using the leaves without the salt: besides, the preserved paste will keep its flavour and strength unimpaired for several years. Other flowers, capable of affording essential oils may also be treated in the above-mentioned way, with economy and advantage; as there is thereby no occasion to carry on a hurried process in the heat of summer, when these are in perfection. 341. GENERAL RULES FOR THE DISTILLATION OF SIMPLE WATERS. 1. Plants and their parts ought to be fresh gathered. When they are directed fresh, such only must be employed; but some are allowed to be used dry, as being easily procurable in this state at all times of the year, though rather more elegant waters might be obtained from them whilst green. 2. Having bruised the subjects a little, pour thereon thrice their quantity of spring water. This quantity is to be diminished or increased, according as the plants are more or less juicy than ordinary. When fresh and juicy herbs are to be distilled, thrice their weight of water will be fully sufficient, but dry ones require a much larger quantity. In general, there should be so much water, that after all intended to be distilled has come over, there may be liquor enough to prevent the matter from burning to the still. 3. Formerly, some vegetables were slightly fermented with the addition of yeast, previous to their distillation. 4. If any drops of oil swim on the surface of the water, they are to be carefully taken off. 5. That the waters may be kept the better, about one-twentieth part of their weight of proof spirit may be added to each after they are distilled. 342. STILLS FOR SIMPLE WATERS. The instruments chiefly used in the distillation of simple waters are of two kinds, commonly called the hot still, or alembic, and the cold still. The waters drawn by the cold still from plants are much more fragrant, and more fully impregnated with their virtues, than those drawn by the hot still or alembic. The method is this:—A pewter body is suspended in the body of the alembic, and the head of the still fitted to the pewter body; into this body the ingredients to be distilled are put, the alembic filled with water, the still-head luted to the pewter body, and the nose luted to the worm of the refrigeratory or worm. The same intention will be answered by putting the ingredients into a glass alembic, and placing it in a bath-heat, or balneum mariæ.