Unofficial Fruits.-Continued. Currant. The fruit of Ribes rubrum. The average constituents are 4 to 7 per cent. sugar, toper cent. albuminous substances, and per Gooseberry. The fruit of Ribes Grossularia. The average constituents are 6 to 8 per cent. sugar, 1 to 11 per cent. free acid (chiefly citric), per cent. albuminous substances, and to 2 per cent. pectinous substances. Peach. Pear. The fruit of Amygdalus Persica. The average constituents are 14 per cent. sugar, per cent. free acid, per cent. albuminous substances, and 6 per cent. pectinous substances. The fruit of Pyrus communis. The average constituents are 7 per cent. sugar, 7 per cent. free acid, per cent. albuminous substances, and 3 per cent. pectinous substances. Pineapple. The fruit of Ananassa sativa. The juice contains 2 per cent. sugar, 1 per cent. free acid, and 3 per cent. albuminous and pectinous substances. Plum. The fruit-trees belonging to the genus Prunus. The average constituents are about 1 to 2 per cent. sugar, to 1 per cent. free acid, per cent. albuminous substances, and 2 to 11 per cent. pectinous substances. Strawberry. The fruit of different species of Fragaria. The average constituents are 3 to 7 per cent. sugar, 1 per cent. free acid, per cent. albuminous substances, and 2 per cent. pectinous substances. QUESTIONS ON CHAPTER LIV. PRODUCTS OF THE ACTION OF FERMENTS UPON ACID SACCHARINE FRUITS. What is white wine? Describe it and give its specific gravity. What is red wine? Describe it and give its specific gravity. What is must? How is wine made? What is meant by the following terms as applied to wines?-viz.: Sweet, dry, light, generous, sparkling, still, sour, rough. What kinds of wine are official? Describe odor, taste, chemical reaction, and solubility. How may the alcoholic strength of wine be ascertained? How much alcohol should wine contain? White wine-How may the following impurities be detected ?-viz.: Tannic acid; limit of fixed residue; limit of acidity. Red wine-How may the following impurities be detected?-viz.: Limit of acidity; aniline coloring. What is the aroma of wines termed, and upon what does it depend? What ethers are said to formed in wines? What are argols? What is the difference between red and white argols? Why are argols deposited during the clarification of wine? What salt is obtained from argols? What are the uses of wine? What alcoholic strength is required of wine for pharmaceutical purposes? Brandy-What is the Latin official name? What is its official definition? Describe the best kind. What kind of brandy is recognized by the U. S. Pharmacopoeia? How much alcohol should brandy contain? Give description and specific gravity. Describe odor, taste, and chemical reaction. How may the following impurities be detected ?-viz.: Fusel oil from grain or potato spirit; an undue amount of solids; added sugar, glycerin, or spices; traces of oak tannin from casks; an undue amount of free acid. To what does brandy owe its aroma? What is cnanthic ether chemically, and what is its commercial name? Is any preparation of brandy official? What is its medicinal use? Tartaric acid-What is the Latin name? Give formula in symbols and molecular weight. How is it prepared? Describe rationale of process. What is its quantivalence? Does it contain water of crystallization? What tartrates are official? How may they be recognized? How may tartaric acid be recognized? Describe rationale of process. Describe odor, taste, chemical reaction, and solubility. Give tests for identity. How may the following impurities be detected?-viz.: Lead and copper; lead, copper, and iron; copper; sulphuric acid. What official préparation contains tartaric acid? To what does lemon juice owe its acidity? How much acid should it contain? What should be its specific gravity? What official preparations are made with lemon juice? Citric acid-What is the Latin name? Give formula in symbols and molecular weight. How is this acid obtained commercially? Describe rationale of process. Describe odor, taste, chemical reaction, and solubility. Give tests for identity. How may the following impurities be detected?-viz.: Tartaric and oxalic acids; per cent. or more of tartaric acid; lead or copper; copper; lead, copper, and iron; sulphuric acid. 1 How much water of crystallization does it contain? What is its quantivalence? What citrates are official? What is the dose? What official preparation is made with it? Sumach-What is the Latin official name? What is it? To what does it owe its acidity? How may malic acid be obtained from it? What is the quantivalence of malic acid? For what is rhus glabra used, and what is the dose? What official preparation is there of it? What is pectase, and what is pectose? To what substance do green, unripe fruits owe their hardness? In the ripening of fruits, what change takes place whereby the fruits are rendered soft? When fruit is over-ripe, what substances are produced? How is the formation of fruit jellies explained? What action do alkalies have upon pectosic acid and pectin? Give an illustration of the application of this principle. Raspberry-What is the Latin official name? What part is official ? Into what official preparation does it enter? How is this made? CHAPTER LV. VOLATILE OILS. VOLATILE oils, or essential oils, are found in the various parts of plants. They usually constitute the odorous principles, and they either pre-exist in the plant, or are produced by the reaction of certain constituents when brought in contact with water. Volatile oils are sometimes formed through destructive distillation, as the oil of amber, and may also be obtained from the animal kingdom, as the oil from ambergris. They may be divided into four classes: 1. Terpenes. 2. Oxygenated oils. 3. Sulphurated oils. 4. Nitrogenated oils. 1. Terpenes, or hydrocarbons, consist of carbon and hydrogen, and mostly have the formula C1H, oil of turpentine being the type. 2. Oxygenated Oils.-Hydrocarbons containing oxygen, like the oil of cinnamon. 3. Sulphurated Oils.-Containing sulphur, like the volatile oil from mustard. 4. Nitrogenated Oils.-A very small class containing hydrocyanic acid, like oil of bitter almond; otherwise, nitrogen is never one of the constituents of volatile oils. Proximately, volatile oils consist of two principles, which differ in their point of volatilization or congelation, or in their composition. They are termed stearopten and eleopten. It is, however, impossible to separate these by distillation alone so as to obtain them entirely pure. When, as often happens, they congeal at different temperatures, they may be separated by compressing the frozen oil between folds of bibulous paper. The solid matter, stearopten, remains within the folds, and the fluid, eleopten, is absorbed by the paper, from which it may be separated by distillation with water. The solid crystalline substances deposited by volatile oils upon standing are also called stearoptens. Some of them are denominated camphors, from their resemblance to true camphor. Some are isomeric with the oils in which they are formed; others are oxides or hydrates, alcohol-like in character. Certain oils, under the influence of water, deposit crystalline hydrates of the respective oils. Color of Volatile Oils.-Most oils are colorless when pure and fresh, or can be made colorless by redistillation. Upon exposure to the air they acquire various colors, becoming green, as in oil of wormwood, yellow, as in oil of peppermint, red, as in oil of origanum, brown, as in oil of cinnamon, or blue, as in oil of chamomile. Odor. The odor of volatile oils is very variable. It is their most characteristic feature. It is sensibly modified by the exposure of the oils to the air. Oil of turpentine may be rectified by distillation in an atmosphere of carbonic acid, or in vacuo, so that it will be odorless, or have an agreeable fragrant odor. A very slight exposure to the air is sufficient, however, to restore the well-known unpleasant odor. Taste. Their taste is almost as variable as their odor. Some are sweet, others have a mild, pungent, hot, acrid, caustic, or burning taste. Density.—The specific gravity of volatile oils also varies (from 0.847 to 1.17). They are mostly lighter than water (see table, page 88). Boiling Point.-This is also variable. The oils volatilize to some extent at ordinary temperatures and diffuse their peculiar odors. Upon heating, however, they may be completely vaporized. When suffi ciently heated, they take fire, and burn with a bright flame. Solubilities. Water is a poor solvent for volatile oils, although it acquires a decided odor and flavor when brought in contact with the oil in a finely-divided state, as has been shown in the medicated waters. Alcohol, ether, chloroform, naphtha, glacial acetic acid, benzin, and benzol are solvents for volatile oils. Alcohol is a better solvent for the oxygenated oils than for the terpenes. Volatile oils freely dissolve fixed oils, fats, resins, camphors, sulphur, phosphorus, and similar bodies. Exposure to Light and Air injures the quality and destroys the fragrance of volatile oils. Ozone is developed, and they thicken and become resinified, or deposit crystalline compounds upon exposure. The whitening of corks which have been inserted in bottles containing volatile oils and kept a long time is due to the bleaching action of the ozone which is gradually produced during their decomposition. They should be kept in tightly-stoppered, amber-colored vials. Action of Acids, Alkalies, etc.-Nitric acid, if strong, decomposes volatile oils with great rapidity. Iodine reacts with some oils with explosive violence. Alkalies have generally little effect on volatile oils, with the exception of a few with which it forms chemical compounds, like the oils from cloves, gaultheria, cinnamon, etc. Adulterations.-The volatile oils are costly enough to tempt the cupidity of those who make a business of adulterating. A fixed oil is sometimes used to mix with the volatile oil. This mixture may be detected by dropping the suspected oil on a piece of filtering-paper. The stain of a pure volatile oil is not permanent. By slightly heating it the oil is vaporized; if fixed oil is present, the stain remains. Alcohol may be detected by shaking the mixed oil in a graduated tube with glycerin or water. The volume of the oil will be diminished, and that of the water or glycerin correspondingly increased, in proportion to the amount used. This test is not susceptible of fine determination, because of the slight solubility of volatile oils in water and in mixtures of alcohol and water. Metallic sodium, calcium chloride, aniline red, have all been used to show the presence of alcohol and traces of water in volatile oils. The adulteration of volatile oils by the addition of cheaper grades of the same oil, or by using a cheaper oil having a similar odor, is largely practised. The only reliable test here is the use of the olfactories. By practice the sense of smell can be highly educated by the analyst. The specific rotatory power, the index of refraction, the amount of iodine absorbed, and the saponification num ber, or the amount of potassium hydrate absorbed by the ester to form a potassium salt, have all been used with more or less success in detecting adulterations. Preparation of Volatile Oils. Volatile oils are generally obtained from plants by the following methods: 1. Distillation with water. 2. Distillation per se. pression. 4. Solution. 3. Ex 1. Distillation with Water.-This is the method most frequently employed. The general formula is as follows: Put the substance from which the Oil is to be extracted into a still (see Distillation, page 166), and add enough water to cover it; then distil by a regulated heat into a large refrigeratory. Separate the Distilled Oil from the water which comes over with it. The substances from which the volatile oils are extracted may be employed in either the recent or the dried state. Certain flowers, however, such as orange flowers and roses, must be used fresh, or preserved with salt or by means of glycerin, as they afford little or no oil after desiccation. Dried substances, before being submitted to distillation, require to be macerated in water till they are thoroughly penetrated by this fluid; and, to facilitate the action of the water, it is necessary that, when of a hard or tough consistence, they should be properly comminuted. The water which is put with the substance to be distilled into the still, answers the double purpose of preventing the decomposition of the vege table matter by regulating the temperature, and of facilitating the volatilization of the oil, which, though in most instances it readily rises with the vapor of boiling water, requires, when distilled alone, a considerably higher temperature, and is at the same time liable to be partly decomposed. Some oils, however, will not ascend readily with steam at 100° C. (212° F.), and in the distillation of these it is customary to use water saturated with common salt, which does not boil under 118.4° C. (227.1° F.) (see page 120). Other oils, again, may be volatilized with water at a temperature below the boiling point; and, as heat exercises an injurious influence over the oils, it is desirable that the distillation should be effected at as low a temperature as possible. To prevent injury from heat, it has been recommended to suspend the substance containing the oil in a basket, or to place it upon a perforated shelf, in the upper part of the still, so that it may be penetrated by the steam without being in direct contact with the water. Another mode of effecting the same object is to distil it in vacuo. Steam can be very conveniently applied to this purpose by causing it to pass through a coil of tube, of an inch or threequarters of an inch bore, placed in the bottom of a common still (see page 133). The end at which the steam is admitted enters the still at the upper part, and the other end, at which the steam and condensed water escape, passes out laterally below, being furnished with a stopcock, by which the pressure of the steam may be regulated, and the water drawn off when necessary. In some instances it is desirable to conduct the steam immediately into the still near the bottom, by which the contents are kept in a state of brisk ebullition (see Fig. 102). The quantity of water added is not a matter of indifference. An |