This alkaloid may be obtained from several species of cinchona, but is most abundant in the yellow bark (C. can/lie/a). The pulverized bark is boiled with water containing 1 per cent of oil of vitriol, which dissolves the bases, that are present; the solution is precipitated by carbonate of soda, and the quinia (with the other alkaloids) extracted from the precipitate by ether. For various methods of obtaining the sulphate of quinia on a large scale for medicinal purposes, we must refer the reader to Pereira's .31ateria ifetlica, 4th edition, vol. ii. part 2, pp. 147440, and the British Pharmacopoeia, p. 315. The mother liquid from which sulphate of quinia has been obtained, contains a con siderable quantity of a resinous amorphous substance known as quinoidine, which. when treated with ether, yields crystals of +4Aq), a base isomeric with quinia, from which again is derived another isomeric base. quinicine.
Cinchonia crystallizes in comparatively large quadrilateral prisms, which are anhydrous. It is less soluble in alcohol than quinia, and is insoluble in ether, and this difference of solubility affords the means of separating these two alkaloids. With acids it forms two series of salts similar to, but more soluble than, those of quinia. These salts are intensely bitter, and possess (although in a less powerful degree) the same thera peutic properties as those of quinia. In certain varieties of cinchona bark, a crystalline alkaloid named cinchonidine, isomeric with cinchonia, occurs. On exposing its salts, or those of cinchonia, to a high temperature, corresponding salts of einchonictne are formed. The last-named substance has the same composition as the two preceding ones, and is precipitated from its salts in the form of a resinous mass. Cinchonia and its isomeric allies are most abundant in the pale Peruvian hark (cinchonia condaminia). The method of obtaining cinchonia is precisely the same as that for obtaining quinia. When both bases are present, they may be separated by converting them into sulphates; the salt of quinia is the least soluble, and crystallizes first.
The relations of the above-described alkaloids to polarized light have been carefully studied by Pasteur, and are.very remarkable. Their resuctite effects on the plane of polarization are as follows: Quinia produces a powerful left-handed rotation; qninidine produces a powerful right-handed rotation; quinicine produces a feeble right-handed rotation: cinchonia produces a right-handed rotation; cinchonidine produces a powerful left-handed rotation; cinchonicine produces a feeble right-handed rotation. The action of these alkaloids thus affords an excellent illustration of the importance of circular polarization as an aid to chemical analysis.* 2. The only preparations of the above-described alkaloids included in the British Phar macopoeia are the sulphate of quinia, the compound tincture of quinia (which is merely a solution of the sulphate in tincture of orange-peel in the proportion of one grain to a fluid dram), and the citrate of' iron and quinia. Sulphate of quinia is a preparation which, from its expense (about 12 shillings an ounce), is always liable to adulteration; and specimens containing gypsum, chalk, magnesia, gum, starch, boracie and stearic acids, sugar, salicine, and sulphate of ciuchonia, are not unfrequently met with. The first five may be detected by their insolubility in alcohol; boracie acid by the green tinge which it gives to the alcoholic flame; stearic acid by its insolubility in dilute maids; sugar by its solubility in cold water; salicine by the addition of oil of vitriol, which turns it red; and the sulphate of cinchonia by precipitating the suspected specimens by liquor anunonim, and then adding ether, when the quinia will be dissolved, but the cinchonia will'float between the two liquids. (This test for ciuchonia is recommeuded
by the French government, who refuse to allow the sale of sulphate of quinia containing more than three per cent of cinchouia.) The most important use of sulphate of quinia is in the treatment of intermittent fever, for which it may be regarded as a specific. Various nervous affections, especially if they assume a periodical character, are success fully treated by it—as, for example, neuralgia, chorea, certain forms of headache, etc. In numerous forms of dyspepsia, debility, and cachexia there is no single remedy more effectual than the citrate of iron and quinia. The ordinary dose of the sulphate is from one to three grains, but in ague it may be given in far larger doses.* It may be pre scribed in the form of pills made with conserve of roses, or as mixture, in which case a little sulphuric acid should be added to render it soluble. In large doses, as from 10 to 20 grains or more, it excites the nervous system, giving rise to headache, buzzing of the ears, blindness, giddiness—a group of symptoms collectively known as pillini8111; and several deaths are recorded as arising from its administration in excessive doses. The average dose of the citrate of iron and quinia is 5 grains, which may be given in a glass of sherry. Quinoidine (also termed amorpholis quinine) seems to be as efficient a tonic as sulphate of quima, but not to have so great an anti-periodic power, and hence not to be so serviceable in intermittent fever, etc. Quinidine possesses the medicinal properties of quinia. - Pereira and other physicians have found that its sulphate is equally serviceable with that of quinia, both as a tonic and a febrifuge; and the action of quinieine is similar to that of quinoidine. Cinekonia appears to act precisely the same as quinia, while einchonidine and einehonieine are of little therapeutic value.
Quinia is employed not merely in the cure of disease, but for the preservation of the health, when the system is exposed to certain noxious influences. Its value as a means of guarding the system from the attack of intermittent fever is so generally recog nized, that our admiralty regulations require that every man should take quinia when the ship is within a certain distance of the e. and w. coast of Africa, and that it should be regularly continued in eight-grain doses every morning to those engaged in boat cruising along the coasts or on the rivers or creeks. The author of A Visit to the (Wes and Camps of the Confederate States, in Blaebcood's Magazine for Jan., 1865, observes, that formerly it was considered certain death to sleep out for one night on James's island, opposite Charleston, during the malaria season; when he wrote, thousands of men were quartered on it. In 1863, when the taking of quinia was optional, there was a great deal of fever; in 1804, all were compelled to take their dose regularly every morning. and they were very healthy. It would appear, however, that quinia is not equally efficacious in guarding the system against all forms of intermittent fever, for Mr. Meller, surgeon naturalist in medical charge of Dr. Livingstone's Zambesi expedition, found a glass of ruin given at sunrise to be "a far better prophylactic" than quinia in the fever of e, central Africa,