with water and sulphuric acid, yields phosphoric acid; this, mixed with charcoal, and distilled, yields phosphoret of carbon, and this by re-distillation becomes phosphorus. Thénard is of opinion that phosphorus cannot be entirely freed from charcoal, a minute quantity of which does not impair its whiteness. Does not this illustrate its easy combustion? Mr. Parkes notes that phosphorus was accidentally discovered at Hamburg, in 1669, by an alchemist named Brandt, in his search after gold; and two years afterwards, one Kraft brought a small piece of phosphorus to London, on purpose to show it to the king and queen of England. Mr. Boyle afterwards discovered the process, which he described in the Philosophical Transactions for 1680, and in a little book which he published in the same year, entitled the Aerial Noctiluca. Mr. Boyle instructed Mr. Godfrey Hankwitz, of London, how to procure it from urine, so that he was the first who made it for sale in England; and he continued to supply all Europe with it for many years. Why does phosphorus shine in the air in the dark, with a pale blue light? Because of its very slow combustion, which is attended by the production of acid: hence the necessity of preserving it in water; this has a luminous property when agitated. The combustion ceases in close vessels, as soon as the greater part of the oxygen has been absorbed. This light is caused by a white smoke; but in air perfectly dry, phosphorus does not smoke, because the acid which is formed, and closely encases the combustible, screens it from the atmospherical oxygen. In the vacuum of the air-pump, phosphorus, in small pieces loosely enveloped in cotton, will generally inflame, and burn for some time, with a pale blue light. and, in the same circumstances, it more readily kindles if sprinkled with powdered resin or sulphur; alone, it does not inflame.-Brande. M. Osam has described, in the Bulletin Universel, several new solar phosphori, which are far more powerful than those previously known. The curious reader will find them in the Arcana of Science for 1829. See also page 53 of the present volume. Phosphorescent phenomena are not uncommon in nature. Phosphorescent fluor spar has lately been found in Siberia and Cornwall. The luminousness of the sea, especially in stormy weather, is supposed to be a phenomenon of this class; but its cause is involved in too much controversy for place here: it was formerly believed to be caused by the electrical friction of the waves, which explanation is no longer admitted. Humboldt attributes it to certain shining molluscæ, which emit light at pleasure, and to the decomposed parts of dead medusæ, &c.* We have elsewhere cursorily noticed the properties of certain phosphorescent bodies. (See p. 52.) Phosphoretted hydrogen may be employed in some simple experiments. Thus, when bubbles of it are sent up into a jar of oxygen, they burn with much splendour; in chlorine, also, they burn with a beautiful pale blue light. Why are brimstone matches used in phosphoric fireboxes Because the sulphur of the match readily combines with the phosphorus in the bottle, by friction against cork or wood, and inflames: indeed, phosphorus and sulphur combined are more inflammable than phosphorus. Why is it difficult to light paper by the flame of phosphorus ? Because the paper becomes covered and protected by the acid formed by the combustion of the phospho *The best recent paper on the subject (for the controversy is still rife among naturalists) will be found in the Magazine of Natural History, for July, 1830. rus. When perfectly dry, phosphorus inflames at a temperature of 600. Why is the phenomenon called "Will-o'-the-Wisp" produced? Because of the phosphuretted hydrogen gas in stagnant waters and marshy grounds; its origin being probably in the decomposition of animal substances. The peculiar odour of fishes, when putrefying, arises from the emission of this gas. COAL GAS. Why does coal, subjected in close vessels to a red heat, produce gas? Because the carbon and bitumen, of which the coal consists, thus become volatilized; and hydrogen, holding carbon in solution, is the result: this gas, combining with the oxygen of the atmosphere, produces combustion and flame. These gaseous products contain also more or less sulphuretted hydrogen, and carbonic oxide and acid. Dr. Henry conceives that gas to have the greatest illuminating power, which, in a given volume, consumes the largest quantity of oxygen. Dr. Clayton seems to have been the first who performed this experiment, with the view of artificial illumination; though its application to economical purposes was unaccountably neglected for about sixty years. At length, Mr. Murdoch, of the Soho Foundry, instituted a series of judicious experiments on the extrication of gas from the ignited coal; and succeeded in establishing one of the most capital improvements which the arts of life have ever derived from philosophical research and sagacity.-Ure. The coal is placed in oblong cast-iron cylinders or retorts, which are ranged in furnaces, to keep them at a red heat, and all the volatile products are conveyed by a common tube into a condensing vessel, kept cold by immersion in water; and in which, the water, tar, pitch, ammoniacal and other condensable vapours, are retained.-Brande. The production of hydrogen gas in a tobacco-pipe, by filling the bowl with powdered coal, then luting it over, and placing it in a fire,—is well known; but even more familiar are the alternate bursting out and extinction of those burning jets of pitchy vapour, which, as Dr. Arnott aptly observes, "contribute to render a common fire an object so lively, and of such agreeable contemplation in the winter evenings." Why was gas adopted in cotton-mills soon after its invention ? Because of the peculiar softness, clearness, and unvarying intensity of its light. Its being free from the inconvenience and danger resulting from the sparks and frequent snuffing of candles, is a circumstance of material importance, tending to diminish the hazard of fire, and lessening the high insurance premium on cotton-mills. Mr. Brande illustrates the economy of gas illumination, by examining the value of the products of distillation of a chaldron of coals, the average cost of which may be considered as £2. It should afford 14 Chaldron of Coke, at 20s. . £150 24 Gallons of Tar and Ammoniacal Liquor at ld. 020 . 7 16 0 £9 3 0 The history and economy of gas-lighting have been copiously illustrated in several volumes exclusively devoted to the subject; as well as by the experimenting skill of some eminent chemists, as Messrs. Henry, Brande, Ure, Accum, and others. From one of these works, aided by the Reports of the late Sir William Congreve, we learn that in the year 1814 there was only one gasometer in Peter-street, Westminster, of 14,000 cubic feet, belonging to the Chartered Gas Light Company, then the only company established in London. In 1827 there were four great companies, having, altogether, gasometers at work capable of containing in the whole 917,940 cubic feet of gas, supplied by 1,315 retorts, and these consuming 33,000 chaldrons of coal in the year, producing 41,000 chaldrons of coke; the whole quantity of gas generated annually being upwards of 397,000,000 cubic feet; by which 61,203 private, and 7,268 public or street, lamps are lighted, in the metropolis. In addition to these great companies, there were several private establishments, whose operations are not included in the foregoing statements; for, it appears that where more than fifty lights are required, a coal-gas apparatus will be found profitable. Thus, the gas for the office of the Morning Chronicle newspaper is made on the premises. According to Mr. Murdoch's statement, presented to the Royal Society, 2,500 feet of gas were generated from 7 cwt. 784 lb. of cannel coal. This is nearly 3 cubic feet for every pound of coal, and indicates judicious management. The price of the best Wigan cannel is 13 d. per cwt. delivered at Manchester; or about 8s. for the 7 cwt. About one-third of the above quantity of good common coal, at 10s. per ton, is required for fuel to heat the retorts. Nearly two-thirds of the weight of the coal remain in the retort, in the form of coke, which is sold on the spot at 1s. 4d. per cwt. The quantity of tar produced from each ton of cannel coal, is from 11 to 12 ale gallons. This tar is now extensively used as paint for out-buildings, &c.; and the ammoniacal liquor, also a result of the process, is turned to still more advantageous account, in the manufacture of carbonate of ammonia; (see p. 119) so that nothing is lost. = Why is it necessary that the cylinders or retorts should be red-hot? Because the gas may be produced instantly the coals are introduced. If, on the other hand, coal be put into a cold retort, and slowly exposed to heat, its bitu |