Gases practically all expand alike; that is to say, for every degree Fahrenheit a gas expands 1⁄491 of its bulk at 32°, and for every degree Centigrade 1⁄273 of their volume at 0°C.
An example will show the importance of this. Suppose an iron bar, connecting two sides of a building, and of a length of about 85 feet. The increase in length by heat of this bar would make it 1 inch longer in summer than in winter; and it would, if no allowance be made, pull or thrust the walls to this extent each year.
EXPEC′TORANTS. Syn. Expectorantia, L. Medicines that promote the secretion of the trachial and bronchial mucus. According to Dr Good, true expectorants are “those medicines which rather promote the separation of the viscid phlegm with which the bronchiæ are loaded, than simply inviscate and dilute it; though these are also treated as expectorants by many writers.” Ammoniacum, antimonials, assafœtida, the balsams of Peru and tolu, benzoic acid, benzoin; the fumes of vinegar, tar, and several of the volatile oils; garlic, ipecacuanha, the oleo-resins, squills, tartarised antimony, and the smoke of tobacco and stramonium, are among the principal substances commonly called expectorants. Tartarised antimony, squills, chlorine, and ammoniacal gases, have also been used (diluted) to provoke the coughing and favour the expulsion of foreign bodies from the air-passages; and also to favour the expectoration of mucus, pus, and membranous concretions, when the local irritation is not sufficiently great. (Schwilgue.) Expectorants are commonly employed in pulmonary complaints and affections of the air tubes, attended by a vitiated state of the mucus, or an imperfect performance of the natural functions of the secretory vessels. “Of all classes of the materia medica, none are more uncertain in their action than expectorants.” (Pereira.) The act of ejecting matter from the chest is called EXPECTORATION.
EXPER′IMENTS are acts or operations intended to develop some unknown fact, principle, or effect; or to establish or demonstrate it, when discovered. Similar operations, performed merely for amusement, are also often, though incorrectly, called by this name. In rational experiments these two objects are combined. To experimental research is due the present high state of advancement and usefulness of the various sciences most intimately connected with our happiness and well-being. The danger of taking things for granted has been thus pleasantly and instructively pointed out by Archbishop Whately:—“It was objected to the system of Copernicus, when first brought forward, that if the earth turned on its axis, as he represented, a stone dropped from the summit of a tower would not fall at the foot of it, but at a great distance to the west; in the same manner as a stone dropped from the masthead of a ship in full sail does not fall at the foot of the mast, but towards the stern. To this it was answered, that a stone, being a part of the earth, obeys the same laws, and moves with it; whereas it is no part of the ship, of which, consequently, its motion is independent. The solution was admitted by some, but opposed by others; and the controversy went on with spirit; nor was it till one hundred years after the death of Copernicus that, the experiment being tried, it was ascertained that the stone, thus dropped from the head of the mast, does fall at the foot of it.”
EXPORTATION. (Exportation on Drawback.) By law, a certain allowance, or drawback of duty, is payable on certain articles, when exported from any part of the United Kingdom, either as merchandise or ship stores. Thus:—
Sugar, refined in the United Kingdom, from 4s. to 6s. per cwt., according to quality.
Tobacco, manufactured in the United Kingdom, 3s. 3d. per lb. The full drawback is only allowed on normal tobacco, which contains 13 per cent. of moisture. If the moisture exceeds 13 per cent., a proportionate reduction is made in the drawback; if it is found less than 13 per cent., a proportionate increase is granted.
Snuff is entitled to drawback at 3s. 3d. per lb., subject, however, to an increase if the moisture is less than 13 per cent., and the inorganic matter not over 18 per cent., and to a decrease if the moisture in organic matter exceeds these per-centages.
Beer. The amount of this drawback is proportional to the quantity of malt or sugar used in the brewing of the beer, and is nearly equivalent to the duty originally paid on such malt or sugar. It is computed according to the following scale:—For every barrel, or 36 gallons of beer, the original gravity of which was not less than 1040°, a drawback of 4s. 3d., and for every additional 5 degrees, from 1040° to 1125° inclusive, a further sum of 6d. per barrel.
Solidified Worts, made by a licensed brewer, from malt or sugar, or malt and sugar, a drawback of 2s. 105⁄100d. per 28 lbs.