He demonstrated that the ratio of the bases to the silica in No. 1 was 1 to 1·58; in the No. 2, as 1 to 0·79; and in the No. 3, as 1 to 0·76. A one per cent. solution of citric acid boiled in the No. 1 did not affect it in the slightest, while in the case of the No. 3, the glassy surface of the enamel was at once roughened and destroyed, and lead dissolved out to such an extent as to give immediately a dense black precipitate with sulphuretted hydrogen. He thought that no enamel was fit to be used unless it were totally unaffected by boiling with a one per cent. solution of citric acid, which was a very moderate test, and gave it as his opinion that either the use of such poisonous ingredients as lead and arsenic in large quantity should be entirely abandoned, or that the composition otherwise of the enamel should
be of such a character as to ensure that none of the poisonous substances could be dissolved out, in the circumstances under which the enamelled vessels are used.
ENCAU′STIC. See Painting (Encaustic).
ENDEMIC. Indigenous. Peculiar to a district. Those are called endemic diseases, which are produced by causes more or less local. The word is often confounded with epidemic.
ENE′MA. Syn. Clyster; En′ema (pl. Enem′ata), L. A medicine, usually liquid (sometimes gaseous), thrown into the rectum or lower bowels.
Clysters usually consist of some weak glutinous or mucilaginous fluid, to which the active ingredients are added; or a decoction or infusion is made of the medicaments, which is then used, either alone, or after the addition of a little gum, starch, or sugar. The proper vehicle for astringent vegetable matter, metallic salts, and the mineral acids, is pure water. Oleaginous and resinous substances are made into emulsions before being employed for enemas. In all cases the fluid is administered warm. The quantity of fluid forming a clyster, for an adult, may vary from 1⁄2 to 3⁄4 pint; that for an infant within a month old, should be about 1 fl. oz.; for a child of one year, about 21⁄2 fl. oz.; from one to seven years, from 3 or 4 fl. oz.; and from seven to twelve or fourteen, 6 or 7 fl. oz.; after that age to puberty, 1⁄2 pint may be employed.
The quantity or dose of the active ingredients in a clyster should be 4 or 5 times as great as that of the same medicines when taken by the mouth; as it is generally regarded that the susceptibility of the rectum is only 1⁄5th that of the stomach, and that to exert a like absorbent action it occupies 5 times as long as the latter viscus. The dose, and the interval between its repetition, should, therefore, be proportionately increased. Narcotics, as opium, tobacco, &c., should, however, be given in only twice or thrice the quantity that would be exhibited in the usual manner.
Enemata are usually administered by means of a syringe, bladder, or elastic bag, furnished with a rectum tube; but many ingenious and elegant pieces of mechanism, adapted for self-administration, are made by the instrument makers. Great care should be taken to avoid injuring the coats of the rectum by the use of a rough or improperly shaped pipe, or one that is too long. The extremity of the pipe or tube should also be perfectly smooth and well rounded (rather spherical than pointed), and in using it no force should be employed. A neglect of this point often produces very serious consequences, especially in young children.
Tobacco smoke may be administered by means of a double pair of bellows, supplied with air from a small funnel under which the herb is burning,—and gaseous matter, by connecting the rectum tube with a small gasometer, exerting a trifling pressure on the confined gas.
The number of substances employed in the preparation of enemata is very great. The following are some of them, arranged according to their effects:—