Burgundy, opposite the table was the statue of a child which was throwing off rose water.

Under Louis XV. the ladies who frequented the court adopted every day a new perfume, in such manner that the rooms in the palace were one day perfumed with tuberose, next day with amber or aloes, and the following days by other perfumes. The variety of these sweet odors, the art of spreading them on the clothes, so as not to offend the sense of smell, gave to that court the name of the perfumed court.

Since that time perfumes have become a necessity to the toilet. The art of perfumery, to which chemistry has given so much help, knows how to fix the most fugitive odors, and offer them under a multitude of forms, the sweetness of which testifies to the salubrity of their use.

'LATION-CONSERVATION AND DRYING OF FLOW

ERS BLEACHING OF SPONGES-CONSERVATION OF PERFUMES.

Decoction.

AN operation which consists in boiling in a liquid an organic substance, so as to extract its active principles. Water saturated with the active principles of the substance, is called a decoction. The decoction is different from the infusion. In the infusion the water is poured while boiling on the organic substances to be exhausted, while in the decoction the substance is boiled with the water. Each operation gives a different result, a plant does not yield the same principles by decoction as by infusion. By decoction, the extractive, resinous, and bitter principles are obtained, while by infusion a larger quantity of aromatic and volatile principles, essences, etc., are extracted. These principles may produce on the animal economy an effect which differs from that which

results from those obtained by decoction. It is then very important not to confound them.

The time of the ebullition is regulated by the nature of the substance treated by decoction. Leaves, and especially flowers, ought to be exposed only to a short ebullition if they are odoriferous; roots and aromatic barks should be subjected to a short ebullition, because the aromatic principles evaporate and are decomposed by the action of heat, or are dissipated. Consequently, it is very important in the preparation of decoctions, to know the way boiling water acts on the different substances, so as to discontinue the operation at the proper time.

Infusion.

Infusion consists in pouring a boiling liquid on an organic substance, so as to extract the principles, and when cool, to separate the product by decantation or filtration. (See Decoction.)

Dissolution.

The operation by which a liquid body communicates that state to any other body, whatever is its nature. The dissolution is also called solution. Any body which disappears in water or some other liquid, without destroying its transparency, is soluble, and the liquid which contains it is called a dissolution. In this state the body has not lost its primitive properties. Sugar, dissolved in water, has

the same sweet taste which characterized it when solid. Water is a precious solvent in the sense that bodies dissolved in it retain their properties. Insoluble bodies render liquids muddy, being deposited after a time more or less long, and form what is called a precipitate or deposit. However, we must not consider as insoluble all the bodies which render water muddy. Very few substances are absolutely insoluble, for the most insoluble, such as sulphate of baryta, chloride of silver, &c., are sensibly soluble; truly, the quantity of water is so great that under ordinary circumstances they may be considered as insoluble. Amongst soluble substances we must not rank those which decompose in water and form new products which are soluble. The dissolution, in separating the molecules, divides bodies so as to weaken those properties which would be too energetic in the solid state. The dissolution offers the best example of the great divisibility of matter. Gases dissolve in proportion to the pressure they are subjected to, while solid substances are generally more soluble in warm than cold water. Lime, magnesia, and zircona are exceptions to the rule. A liquid which has dissolved a substance in so great a quantity that it cannot dissolve any more of the same substance under ordinary circumstances, is called a saturated solution. When a substance is more soluble in a warm than in cold liquid, the dissolution saturated at the ordinary

temperature will dissolve a larger quantity when warm, then it is super saturated, and when allowed to stand and cool slowly, the excess of the soluble body is deposited, and the molecules assume peculiar geometrical forms called crystals.

Maceration.

An operation which consists in allowing to stay together for some time, at the ordinary temperature, a solid substance and a liquid, for the purpose of dissolving some of its immediate principles, or to extract the soluble principles, or, lastly, to preserve them.

Filtration.

An operation which consists in passing a liquid through a porous body, which retains the solid substances. It has for its object to clarify the liquid, or to collect the solid bodies mixed with it, or to attain these two results at the same time. Sometimes the filter is a piece of felt, or a frame. covered with a piece of woollen or cotton cloth, or even a piece of filtering paper; sometimes it is composed of vessels with several bottoms, pierced with holes and covered with one or several beds of straw, cotton, sand, or charcoal. Generally, it is necessary that the filtering substance should be porous, or so divided as to let the liquid pass and retain the foreign bodies which are suspended

in it.