DEAF′NESS. An imperfection or absence of the sense of hearing. When deafness is present in infancy and childhood, it is accompanied with dumbness, or imperfect articulation, in consequence of the impossibility of conveying a knowledge of the sounds necessary for the exercise of the imitative faculty of speech. Deafness frequently arises from some imperfection or obstruction of the passage leading to the membrane of the tympanum or drum of the ear. In some cases this passage is totally closed by a membrane, or some malformation of the tube, which may frequently be removed by a surgical operation. Even instances of partial obliteration of this passage have occurred, which have been successfully treated. The researches of Mr Yearsley have established the fact, that enlarged tonsils are a very common cause of deafness; and when such is the case, their excision will generally effect a cure. To this form of the affection Mr Yearsley applies the term ‘throat deafness.’ Another cause of deafness is the presence of foreign bodies in the aural passages or the accumulation of hardened wax. In these cases the best treatment is to inject warm water into the ear by means of a proper syringe. When deafness arises from imperfection of the tympanum or drum of the ear, the effects of the application of the artificial membrana tympani invented by Mr Yearsley (moistened cotton wool) are generally immediate and truly wonderful. By its aid persons previously so deaf as to be incapable of bearing their share in conversation have been enabled to hear an ordinary whisper. Insects may be destroyed by pouring a spoonful of warm olive oil, or camphorated oil, into the ear over night, retaining it there until the next morning by means of a piece of cotton wool, when it may be washed out with a little mild soap and warm water. When there is a deficiency of the natural secretion of wax, or a dryness of the aural passage, mild oleaginous stimulants may be employed. For this purpose a little olive oil, almond oil, to which a few drops of oil of turpentine, oil of juniper, or camphor liniment, have been added, may be used with advantage. A piece of cotton wool moistened with glycerin is an excellent application in such cases. When deafness is accompanied with continued acute pain, or a discharge of purulent matter, inflammation of the tympanum, or some other portion of the internal ear, probably exists, and medical advice should be sought as soon as possible. The deafness that frequently accompanies a violent cold is generally caused by obstructions in the Eustachian tubes, and goes off as soon as the secretions return to a healthy state. In some forms of deafness blisters behind the ears are useful. A clove of garlic wrapped in cotton or gauze, or a few drops of the juice introduced into the ear, is extremely efficacious in nervous deafness. When imperfect hearing depends upon obtundity of the auditory nerve, or an extensive obliteration or malformation of the internal ear, it scarcely admits of cure.
Deafness, Taylor’s Remedy for. Prep. From oil of almonds, 1 lb.; garlic, bruised, 2 oz.; alkanet root, 1⁄2 oz.; digest for a week, and strain. A little is poured into the ear in deafness.
DEATH. In cases of sudden death interment should be deferred till signs of putrefaction begin to appear, especially when no gradation of disease has preceded, as in cases of apoplexy, hysterics, external injuries, drowning, suffocation, &c. No sooner has breathing apparently ceased, and the visage assumed a ghastly or a death-like hue, than the patient, after his eyes are closed, is too often hurried into a coffin, and the body, scarcely yet cold, is precipitated into the grave. So extremely fallacious are the signs of death that the semblance has been frequently mistaken for the reality. By prompt means and judicious treatment, many persons, when in such a condition, have been happily restored to their families and friends. The effects of sound upon animal life is astonishing. The beat of a drum, for instance, has had a very beneficial effect upon persons in a state of suspended animation. At one time a scream, extorted by grief, proved the means of resuscitating a person who was supposed to be dead, and who had exhibited the usual recent marks of the extinction of life. In cases of catalepsy or trance, having the semblance of death, the action of the lungs and heart continues, though in a nearly imperceptible degree. By placing a cold mirror or piece of highly polished metal immediately over the mouth of the patient, symptoms of moisture will appear upon the surface if the most feeble respiration takes place.
DEBIL′ITY. Syn. Debil′itas, L. Weakness; languor; feebleness. When this arises from a diseased action of the stomach, the occasional use of mild aperients, followed by bitters and tonics, may be had recourse to. When from a general laxity of the solids, and there are no symptoms of fever, nor a tendency of blood to the head, a course of chalybeates generally proves advantageous. See Anæmia, Atrophy, &c.
DECANTA′TION. The operation of pouring or drawing off the clear portion of a liquid from the impurities or grosser matter that has subsided. It is commonly performed, either by gently inclining the vessel, or by the use of a syphon or pump. In the laboratory it is much resorted to in the purification of precipitates, or other similar operations, where repeated edulcoration or washing is required, for which purpose it is preferable to filtration, from being less troublesome and more economical. In these cases, after a sufficient time having been allowed for the subsidence of the precipitate or powder, or for the clearing of
the supernatant fluid, the latter is decanted, and its place supplied by a fresh portion of water, which, after sufficient agitation, is similarly treated, and the whole operation repeated as often as necessary.
DECANT′ERS. There is often much difficulty experienced in cleaning decanters, especially after port wine has stood in them for some time. The best way is to wash them out with a little pearlash and warm water, adding a spoonful or two of fresh-slaked lime, if necessary. To facilitate the action of the fluid against the sides of the glass, a few small cinders or pieces of raw potato may be used. A spoonful of strong oil of vitriol will also rapidly remove any kind of dirt from glass bottles. Decanters which have become furred by holding hard water may be cleaned with a spoonful of hydrochloric acid (‘spirits of salt’), diluted with 3 or 4 times its weight of water. See Stoppers.
DECARBONISA′TION. This operation is performed on cast iron, to convert it into soft iron. The articles to be decarbonised are packed in finely powdered hæmatite, or native oxide of iron, to which iron filings are often added, and exposed for some time to a strong red heat, by which the excess of carbon is abstracted or burnt out. The process somewhat resembles annealing or cementation.
DECAY′. See Eremacausis.
DEC′IMALS. Syn. Decimal fractions. Fractions which have for their denominator 10, or some power of ten; as 100, 1000, &c.; the number of ciphers in the denominator being always equal to the number of figures in the numerator. Thus, ·2, ·25, ·125, respectively represent 2⁄10, 25⁄100, 125⁄1000. The denominator of decimals is never written, the dot placed before the first figure of the numerator expressing its value. Ciphers placed on the right hand of a decimal fraction do not alter its value; for ·5, ·50, ·500, are each equal to 1⁄2; but ciphers placed on the left hand of a decimal diminish its value in a tenfold proportion; thus, ·3, ·03, ·003, respectively answer to the common fractions 3⁄10, 3⁄100, and 3⁄1000. Every figure on the left-hand side of the dot or decimal sign is a whole number.