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1. Distillation.-This art is founded on the different tendencies which bodies have to pass into vapor, and to be condensed again by cold. It is employed in order to separate the more volatile substances, such as alcohol, the essences, essential oils, &c., from other substances with which they are combined. This is accomplished, by applying heat to the compound, so regulated, that the volatile liquid will rise in vapor, leaving the other in a liquid state; and this vapor is then condensed, by passing through a worm, immersed in cold water. Sometimes the operation is conducted in a vessel, from which the air has been expelled; and in that case, as fluids boil in a vacuum, at a temperature much below that at which they boil in the air, the extract is obtained in its most perfect state.

In the case of the essential oils, water is put into the still, along with the plant, in order to prevent the latter from being burned. The oil and water both pass over into the receiver, and the oil collects at the top or bottom of the water, according to its density. These oils are very useful, as solvents in the arts, and as medicines. In these respects they might often be advantageously substituted for alcohol, which, unfortunately for the world, has enjoyed much more repute than it deserves. It is doubtless useful in some chemical and pharmaceutical processes, and affords a very convenient solvent for resins, balsams, and the vegetable alkaline principles. It is certain, however, that on many occasions, when we now resort to it, the essential oils, or some other substitute, might subserve the same purpose. A distinguished physician, when speaking of its use, as a medicine and as a beverage, says, "But if useless as a preventive, is not alcohol important in the treatment of disease? admit that it is sometimes convenient; but I deny that it is essential to the practice of physic or surgery. Do we wish to rekindle the taper of life, as it glimmers in a fainting fit; we have ammonia, and the volatile oils; and, what is better than every thing else, cold water, to be administered by affusion. Is it required to produce

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a tonic effect, in the case of long-standing debility? the tonic roots, and barks, and woods, impart their invigorating properties to water and acid. Are we called upon to relieve pain ? opium is altogether superior to alcohol. Do we need a solvent for opium? we have it in the acetous acid. The black drop is one of the best solutions of opium ever invented.

"But what is to be done with the medicinal resins and aromatic oils,-must not they be dissolved in alcohol? The medicinal resins do not constitute a very important class of remedies; but they may be given in fine powder, rubbed with some inert friable substance, or dissolved in an essential oil, or made into an emulsion. The ordinary mode of using them does not carry them into the stomach in the state of solution, as they are instantly precipitated, in a flocculent form, on being thrown into water. As for the aromatic oils, they may be given in the form of liquid soap, or emulsion, rubbed with alkali, or sugar and water; and in this way they exert their specific effects.

"Is the physician required to prescribe a restorative? if quinine and bark, and bitters and metallic tonics, will not do, shall he prescribe alcohol? This is never certain, and always unsafe, inasmuch as there is imminent danger of a permanent relish being acquired for it; nor does it compare, in its restorative powers, in cases where the complaint was not produced or modified by the previous use of it, with the pure fermented and well preserved juices of the grape and the apple. The factitious wines, extensively vended in our country, are poor restoratives; they contain a large proportion of alcohol.

"I maintain, then, that, taking into view the danger of making tipplers, by giving ardent spirit to the sick, and considering that all its medicinal virtues are found in other articles, mankind would not, on the whole, be losers, if it should be banished, not only from the houses of every class of the community, but also from the shops of the apothecary.

"What is the secret of the witchery, which strong drink exerts over the whole man? I will try to tell you. After being received into the stomach, it is sucked up by absorbent vessels, is carried into the blood, and circulates through the alimentary organs, through the lungs, muscles, and brain, and doubtless through every organ of the body. Not a bloodvessel, however minute, not a thread of nerve, in the whole animal machine, escapes its influence. What is the nature of this influence? It disturbs the functions of life; it increases, for a time, the action of living organs, but lessens the power of that action; hence the deep depression and collapse which follow preternatural excitement. By habitual use, it renders the living fibres less and less susceptible to the healthy operation of unstimulating food and drink, its exciting influences soon become incorporated with all the living actions of the body; and the diurnal sensations of hunger, thirst, and exhaustion, are strongly associated with the recollection of its exhilarating effects, and thus bring along with them the resistless desire for its repetition.

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2. Culinary Processes.-The preparation of vegetable and animal food depends almost entirely upon the proper management of heat. It is applied in two principal ways; first, through water, for the purpose of extracting from vegetable and animal substances their nutritive or exhilarating principles. We have examples of this, in the making of tea, coffee, soups, &c. Hot liquids are much more powerful solvents than cold ones; and hence, by boiling a substance in water, its soluble parts will be extracted and mixed with the fluid. In conducting this operation, two things require special attention; first, the quality of the water, which is often mixed with foreign substances, such as lime and calcareous salts. These render water hard, and may be precipitated to the bottom of the vessel, either by boiling, before we use the water, or, more perfectly, by adding a little soda or potash. This effect of boiling explains why tea-kettles and boilers are so frequently

incrusted on the inside. The quality of the water may be ascertained, before using it, by adding soda or potash. If it be impure, it will become turbid, and a white powder will be precipitated.

The second thing to be attended to, in boiling, is the vessel. As it is an object to secure a high heat, the vessel should be so constructed, as, on the one hand, to conduct the heat rapidly from the fire to the fluid within, and on the other hand, to prevent its escape at the sides and top. This is effected, in part, by having the bottom of the vessel black and rough, since such surfaces absorb heat more readily than those which are smooth and light colored. On the same principle, the top and sides should be polished, and of lighter color. It is also important, if we would maintain a high temperature, at the least expense of fuel, to keep the vessel closely shut, in order to prevent the escape of heat by radiation and conduction, and also, (since steam forms at two hundred and twelve degrees Fahrenheit,) in order to prevent steam from passing off through the spout or top, and thus occasioning a waste of heat. On this account, a vessel has been constructed, for the special purpose of preventing such escape of heat. It is called Papin's digester. The top and sides are surrounded with a non-conducting substance; the vessel is kept perfectly closed, and the temperature of the contained fluid is often four hundred degrees. It has been found sufficient to dissolve animal bones, and is used in extracting from them the gelatin which forms the principal material in the portable soup, which is taken on long voyages, &c. Boiling is used not only to extract the soluble parts of vegetable and animal substances, but also to fit these substances themselves for becoming food. The precise change which it effects is but imperfectly understood. We know that vegetables, such as potatoes, &c., which, before boiling, are watery, ill-flavored, and extremely indigestible, are rendered, by this process, dry, farinaceous, and very digestible; and it is pretty well ascer

tained that this change consists, not merely in the softening of the fibres, the solution of some and the coagulation of others, of their juices and principles, but that these principles are decomposed, and combined anew, so that they are no longer distinguishable by the forms and properties which they previously possessed.

This remark applies, also, to the changes produced by dry-heat, on vegetable and animal substances. Bread, for example, by being baked, is not only rendered lighter, by the expansion of the gas contained in the paste, but its constituent principles are so completely changed, that, on analyzing it, the proximate ingredients of the flour are no longer to be found. So in the roasting and baking of fruits, we sometimes find acid destroyed, saccharine matter formed, mucilage and gelly extracted, or combined anew, so that the product exhibits properties very different from those of the raw material. The same is true of meats. When baked or stewed, the jelly, oil, and albumen, are separated, dissolved, mixed, or combined anew. Perhaps the simplest form of preparing meat is by roasting. Here, some changes, both of texture and composition, take place, but not so great, but that we can still detect, on analysis, many of its original properties.

Before leaving the culinary processes, it might seem proper to advert to various spices and condiments, which are employed in giving flavor to food. To the influence which they exert, in preventing decay, we shall refer hereafter. The manner in which their flavor is extracted, by heat and by fluids, must be sufficiently obvious. We proceed to consider,

3. The Management of Milk.-If milk be allowed to stand, it will separate into three distinct parts, of which it is composed. The cream, being the lightest, rises to the top, and the remainder, soon becoming sour, will be resolved into a solid coagulum, called curd, and a limpid fluid, which is whey. The separation of the curd from the whey may be produced artificially, by an acid; or by means of rennet, which is an infusion of the

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