volume, but must go back to his university work in Germany, hoping to return in a few years' time, when the volume had been published. Then Bunsen told him that it had been the dream of his own youth to go to India to find out whether the Vedas did really exist, and could be published and translated, and that a young American, whose private tutor he had been at Göttingen, had once promised to meet him in Italy, and go to India with him. Bunsen went to Italy and waited for his friend, but the friend never came; he himself met with Brandis and Niebuhr, and fell into a new career, where his first love was forsaken, but not forgotten. When Bunsen had told Müller this, he turned to him and said, 'Now, in you I see myself young again, and what I can do for you I will. You must stay in England till your collections are finished; and if you want money I shall write you a cheque.' It was through the Prussian Ambassador's influence that the East India Company were induced to bear the expense of the publication, now approaching completion, of a work of such paramount importance to Englishmen, whether they look at it as enabling them, now for the first time, to understand the religious system against which their missionary efforts are directed in India, or as recording for their students primæval history of the life, the art, the language, the thought, the belief, of the great race to which they trace their ancestry. We may refuse to recognise Bunsen's system of chronology-we may judge of his reconstruction of early history that he is prone, like his master Niebuhr, to imagine instead of to infer; but he was not only a learned, but a good and great man; and no one who has known and honoured him would willingly pass by an occasion of making known one more example of his disinterested zeal for the advance of knowledge. Nor was the obligation a slight one which he laid us under in leading Max Müller to become in England the trainer of an English school of philologists. ART. V.-1. The Coal Question: An Inquiry concerning the Progress of the Nation, and the probable exhaustion of our Coal-Mines. By W. Stanley Jevons, M.A., Fellow of University College, London, and of the Statistical Society. Macmillan and Co., 1865. 2. Reports received from Her Majesty's Secretaries of Embassy and Legation respecting Coal. With an Appendix. Presented to both Houses of Parliament by command of Her Majesty. 1866. 3. Coal, Smoke, and Sewage, scientifically and practically considered sidered; with suggestions for the Sanitary Improvement of the Drainage of Towns, and the beneficial application of the Sewage. Being the substance of a Paper read before the Literary and Philosophical Society of Manchester. By Peter Spence. Manchester, 1857. Pamphlet. 4. The London Corporation Coal Tax. An Explanation of the Origin, Progress, and Operation of the Tax, constituting at present an Annual Charge of above 187,000l. on a prime Necessary of Life throughout the whole area of country within twenty miles of the General Post-Office. By John Dickinson, Esq., F.R.S. London, 1854. Pamphlet. The Metro 5. To the Vestrymen of the Metropolitan Districts. By HERE is no question of more momentous concern to Great question which of late has excited the attention both of statesmen and philosophers. It was referred to in anxious terms by Mr. Graham, the Member for Glasgow, in seconding the address at the recent opening of Parliament. Sir Robert Peel, in his speech of the 9th of March last, in the House of Commons, on the nuisance arising from the smoke of furnaces in towns and rural districts, sounded notes of alarm at the enormous and yearly increasing consumption of coal; and in the course of the debate which followed, other speakers expressed similar apprehensions. On the other hand, it is maintained that the supply of our mineral fuel is practically unlimited; and some persons, with as much presumption as ignorance, have even ventured to predict that several thousand years will elapse before our collieries are exhausted. It will not be denied that our marvellous prosperity has mainly resulted from our manufacturing power, and that this power is for the most part to be ascribed to our coal. It is also evident that the position of Great Britain among the nations of the earth depends in a great degree upon her wealth, and that this wealth has been chiefly accumulated by manufacturing enterprise. Hence the 'Coal Question,' as Mr. Jevons terms it, may be justly considered as of vital importance to all the dwellers in the land, high as well as low, rich as well as poor. Notwithstanding the boasted enlightenment of the present age, it is really astonishing how defective is the information, even of many highly-educated persons, concerning such a familiar object as as coal. It may be well, therefore, to preface this article with a short description of the nature, origin, and varieties of coal. Amongst the different kinds of matter constituting the earth, which chemists have hitherto failed to resolve into other kinds of matter, and which, therefore, they designate elementary bodies or elements, one of the most remarkable is carbon. It occurs in definite geometrical figures, that is, crystallized; or without form, that is, amorphous. It crystallizes in what mineralogists term the cubical and the rhombohedral systems, when it appears respectively as the queen of gems, the diamond,-and as the black, opaque, greasy substance, graphite or black lead. In the amorphous state, carbon is familiar to us as charcoal. The diamond is known only as a natural product, and chemists have been utterly baffled in their attempts to prepare it in the laboratory. As a few cubic feet of space would probably contain all the diamonds that have ever been collected, it may be inferred that the conditions necessary to its formation must have been exceedingly rare. Still, on chemical grounds, its artificial production may be reasonably anticipated. Graphite or carbon, crystallized in the rhombohedral form, is daily generated in large quantity at our iron-works. Carbon has a strong liking, or, as it is technically termed, affinity for oxygen. When a piece of common charcoal is ignited and exposed to the air, it burns, smoulders away, and finally disappears, leaving only a little white earthy matter or ash. In thus burning it combines with the oxygen of the air, and the product of the combination, or combustion, is the heavy, colourless gas, carbonic acid, a gas which all animals exhale in expiration, and which sooner or later destroys animal life. Carbonic acid consists of carbon and oxygen in the proportion (by weight) of 1:2; and carbon is incapable of combining with a greater proportion of oxygen than exists in carbonic acid. But there is another compound of these elements to which particular attention must be directed, namely, carbonic oxide. It contains just half the quantity of oxygen existing in carbonic acid, that is, carbon and oxygen in the ratio of 1:14. This gas is somewhat lighter, bulk for bulk, than atmospheric air. In contact with the air it burns with a beautiful blue flame, and is converted into carbonic acid. It is exceedingly poisonous. It is always formed when carbonic acid comes in contact with carbon heated to bright redness. Thus it is produced when a layer of charcoal a few inches in depth is burned in a stove or furnace. The oxygen of the air, which passes through the grate at the bottom, forms carbonic acid the moment it impinges upon the charcoal; but immediately afterwards this acid, in ascending through the over lying incandescent mass, takes up an additional quantity of carbon and is changed into double its volume of carbonic oxide, which, if a suitable supply of air be admitted at the top of the furnace, will burn with flame, forming carbonic acid. The reader should also bear in mind the following important facts concerning the heat-giving power of carbon :-One part by weight of charcoal on perfect combustion, that is, in combining with the maximum of oxygen, evolves heat sufficient to raise 8080 parts by weight of water 1° centigrade. But it may be shown that in imperfect combustion, as in the case of the production of carbonic oxide, one part by weight of charcoal will only raise 2473 parts by weight of water 10 centigrade. Hence it will be perceived that if in the burning of charcoal any carbonic oxide is allowed, from insufficient supply of air, to escape from a chimney, great waste of heat will result, and that when carbonic acid is converted into carbonic oxide there will be absorption of heat. The facility with which carbon is ignited and burns in contact with oxygen, whether pure or diluted as it exists in atmospheric air, varies greatly with the state of aggregation. Thus, compared with charcoal, diamond and graphite are very difficult of combustion. But the same also is true, though in a less degree, of common varieties of carbon which are used as fuel. Carbon is one of the chief components of the minerals which constitute the crust of the earth. Limestone, marble, and chalk consist essentially of carbonic acid and lime, or, in the language of chemists, of carbonate of lime. These three substances, which differ considerably in external characters, contain the same proportion of carbon, namely, 12 per cent. Each, however, may vary somewhat in composition, owing to the accidental presence in greater or less degree of other matters, such, for example, as sand and oxide of iron. Then there is magnesian limestone, which is formed of carbonate of lime and magnesia. Few persons now-a-days can be so ignorant of geology as not to know how largely carbonate of lime in one form or other enters into the constitution of the surface of the globe in Europe, Asia, Africa, America, and Australia. Carbonic acid is also universally present in the atmosphere, and may be computed at between 004 and 0.05 per cent. Carbon is a necessary element in the fabric of every plant and every animal, and there can be no life without it, at least on this planet. But enormous stratified deposits, rich in carbon, are found below the surface of the earth, cropping out here and there in consequence of subterranean disturbance. These are our beds or seams of coal. It is established beyond the possibility of question that that all coal is the product of the decay of vegetable matter, and the evidence may be found in any geological treatise of repute. Vegetable matter consists essentially of carbon, oxygen, hydrogen, a small proportion of nitrogen, and ash. The hydrogen is slightly more than suffices to form water with the oxygen, so that vegetable matter may be practically represented as composed of about 50 per cent. of carbon, 46 of water, 1 of hydrogen in excess, and 3 of ash, inclusive of nitrogen. Now, in proportion to the degree of decay will be the relative increase in the percentage of carbon in coal, and the final stage is reached in the variety of coal, termed anthracite, which may contain upwards of 90 per cent. of carbon. Between unchanged vegetable matter and anthracite every gradation of change is observed. An excellent illustration of this kind of change is presented by a peat bog, where moss, which in Europe is the source of peat, may be seen growing at the top and gradually passing into peat underneath; and at the bottom decay may have so far advanced as to have yielded black peat free from all appearance of vegetable structure. What takes place in this transformation of moss into peat is precisely similar in kind to what takes place in the conversion of vegetable matter into coal. The difference between the two cases is simply one of degree. Just in proportion as decay progresses in moss, will the proportion of carbon in the product relatively increase. During this decay carbon is evolved in two states of combination, namely, with oxygen as carbonic acid and with hydrogen as marsh-gas or firedamp; and water is also separated. Every person must have remarked that on plunging a stick into the muddy bottom of a pool bubbles of gas have immediately escaped. This gas is composed of the two gases just mentioned, carbonic acid and marshgas, and proceeds from the decay of the vegetable matter in the mud. It may be shown that the formation of every one of the numerous varieties of coal may be explained by the elimination from vegetable matter of carbonic acid, marsh-gas, and water, in various proportions. This change has continued in coal long after it had been deposited and covered over with strata thousands of feet in thickness; and, indeed, it may still be progressing. On listening near a newly-cut face of coal in a pit, the gas may frequently be heard to escape with a peculiar singing sound; but occasionally on the blow of the pick a sudden and enormous eruption of gas has been known to occur, filling all the workings in the course of a few minutes, and so endangering the life of every collier underground. It should be stated that during the formation of some coal the gases must have had the opportunity of freely escaping, for in certain collieries fire-damp is unknown. |