deposits pass, however, from Spain into the adjoining part of Portugal. Some of the deposits are nearly a mile long, of great depth, and of varying width. Till lately, the great bulk of pyrites imported was brought chiefly from Mr. Mason's mines, near the river Gaudiana. The owner was the first person to construct a railway as a means of transport from the mines to the coast, instead of the antiquated and expensive method of mule carriage. Mules are still employed at all the other mines, and the mineral is carried in sacks or baskets on the mules' backs. A few years since, the Tharsis Mining Company, consisting chiefly of Glasgow capitalists, was formed to purchase and work a number of mines. The pyrites from the Tharsis mines are now used largely, and the imports of Mr. Mason's ore have been much reduced. The latter usually contains about 50 per cent of sulphur, besides 3 or 4 per cent of copper. The Tharsis mineral contains 45 to 50 per cent of sulphur, and 4 to 5 per cent of copper. Both kinds are much the same in their working qualities; they burn well, and make comparatively little dust in breaking. Norwegian Pyrites.-Many mines of pyrites occur in Norway, but those in the vicinity of Drontheim are the most important. The Norwegian ore is pretty largely imported into this country, but chiefly to the Tyne. The largest quantity is raised in the mines Ytteröen, the annual product being from 6,000 to 8,000 tons. It consists of very small crystals, is of good quality, burns well, and does not slag in the kilns. It contains about 44 per cent of sulphur, and from 1 to 2 per cent of copper. Under this head Mr. Mactear referred to a second quality of this mineral; to an excellent variety obtained about 30 miles from Drontheim, and containing but a trace of copper; to the ores obtained from some mines opened lately near Bergen; and to another variety which comes from Nordland, yielding 42 per cent of sulphur. Swedish Pyrites.-This is obtained in mining for copper ores, and is said to exist in enormous quantities, but at present the want of means of cheap transport to convenient shipping prevents it coming into extensive use. A few cargoes, however, have found their way to Britain, and the ore itself has been found to work. Belgian Pyrites.-Large quantities of this ore are imported, especially to the Tyne-the freight from Antwerp being very low, sometimes only 6d. per ton. The mines yielding it are in the districts of Liege and Namur, and are worked primarily for lead and zinc ores. One kind is called alluvial pyrites, and has the form of coprolites, and few of the pieces weigh more than a pound each. It burns well if used along with Norwegian or other ores. Another resembles a slag or cinder, and often contains lead or antimony Belgian ores contain from 40 to 50 per cent of sulphur, and traces of thallium. Westphalian Pyrites.-This resembles a very poor fire-clay, or shale, in appearance, but it burns well. It is said to contain a considerable quantity of thallium. The analysis gives 42 to 45 per cent of sulphur. Italian Pyrites.-Very little of this is imported, for although it contains about 45 per cent. of sulphur, it also contains 9 to 10 per cent of silica, and its physical properties are not in its favour. Irish Pyrites.-This is obtained from the Wicklow mines, where it occurs in beds of great thickness. It contains from 30 to 35 per cent. of sulphur. A deposit occurs in the Vale of Avoca, which contains about 44 per cent of sulphur. Cornish Pyrites.-Under this head the author included the ore from the mining districts of Dorset, Devon, and Cornwall. It is got in the dressing of the lead and copper ores, and usually contains from 25 to 30 per cent of sulphur and 1 or 2 per cent. of copper, and frequently arsenic. The author also referred to the fact that Mr. Vivian is making sulphuric acid by burning copper pyrites in kilns of peculiar construction. Coal Brasses. This material, also called "Scotch gold," is largely used, and is a cheap source of sulphur for acid to be used in making manures, &c. Even when well cleaned it always contains organic matter, and possesses other disadvantages; still it is useful in keeping up heat in the kilns if used along with other varieties. Cleveland Pyrites.-Although interesting to the geologist, this mineral is of little interest to chemical manufacturers, and the author said he only knew of one establishment where it is used—one near Middlesbro'-on-Tees. The author concluded his paper by referring to the sul phur-recovery process, patented by M. Mond, and now being practically applied under his (the author's) care at St. Rollox Chemical Works. Several members of the Society spoke on topics suggested by the paper; a vote of thanks was passed to Mr. Mactear. Chemical Section, 4th May, 1868. ALEXANDER WHITELAW, Esq., Treasurer, in the Chair. AT this, the last meeting for the session, a paper was read by Dr. Wallace, F.R.S.E., F.C.S., analytical chemist, on "The Animal Charcoal used in Sugar Refining." Dr. WALLACE stated that his communication to the Section was not to be dignified by the name of a research, but as his name had been associated with the chemistry of sugar-refining during the last ten years, he thought it likely that as a result of his observations and experiments he night be able to mention some things not contained in books. He stated briefly the mode of making animal charcoal from bones, and mentioned the principal Scottish manufacturers of the substance. All the bone char made, in Glasgow, Paisley, and Greenock, in addition to a large quantity imported from France and Russia, is used in the Clyde refineries. A large amount of it is manufactured; for notwithstanding the fact that the charcoal lasts a considerable time, it has to be occasionally renewed, owing to the stock gradually dwindling down from various causes. The author calculates that the quantity of animal charcoal in actual use in the Clyde refineries is probably well nigh 5,000 tons, and that the annual renewal is probably about 1,500 tons. The carbonisation of the bones is usually continued for twelve hours, that length of time generally giving better charcoal than when the bones are only carbonised for six hours, even though in the latter case the heat is made stronger. After the bones are charred they are crushed between rollers, and the charcoal is ready for use when the dust is removed. The quality of the char varies with the kind of bones employed, and the care observed in the charring operation. Hand-picked home-collected bones make the best charcoal. Besides these there are the shank bones from the Saladeras of Brazil and Buenos Ayres; camp bones dug up from old battle fields, and bearing evidence of having been buried for a long time, and the charcoal from which may be easily distinguished from that prepared from home-collected bones; and there are also large shipments from Italy and Turkey, including the bones of the camel along with those of cattle, antelopes, sheep, and horses. In the analysis of the best charcoal from home-collected bones, carbon usually occurs to the extent of about ten per cent, the remainder being the phosphates and other mineral ingredients of the natural bones. The carbon varies with the amount of grease and gelatin left in the bones after boiling, and it also varies in the different parts of the same bone, -the hard exterior containing less than the extremities and spongy interior of the bone. Charcoal as met with in commerce usually contains about ten per cent of water, as water is used to cool the char as it is drawn from the retorts. The author then stated generally the method of conducting the analysis. It presents certain difficulties notwithstanding the apparent simplicity of the composition of bone charcoal. He instanced carbonic acid as offering some difficulty, and said that his own method of estimating it was less compli cated than the one given by Fresenius, although the latter is otherwise equally good. The method used by some chemists of precipitating the phosphate of lime, and then throwing down the lime in the filtrate in the usual way, he NEWS characterised as giving entirely fallacious results. Free proportion of carbon may increase during use from 8 or 9 per cent to 14, 15, or even 19 per cent,-this increase being derived from the organic impurities in the sugar. The carbon obtained in the carbonisation of these impurities is deposited partly on the surface, but largely also in the pores. This is found to be a great evil, and a great point is gained if it can be prevented. That it can be prevented is proved by the fact that in some refineries the amount of carbon does not increase, while in others it even decreases, but this is owing to mismanagement in the reheating. When the retorts are quite tight, and the heat not excessive, the carbon necessarily increases if the precaution be not taken to wash well before re-burning, so as to remove all the organic matter absorbed from the sugar liquor. To do this, boiling water is requisite, and one of the most advanced of the Clyde sugar-refiners insists that the charcoal should even be boiled with the water. The author's experience accords with that of the sugar-refiner referred to. In ordinary cane sugars there is from to I per cent of soluble mineral matter, consisting of salts of potash, soda, lime, and magnesia; and in beet sugars there is much more Traces of ammonia always exist in new char, but the-from 1 to 3 per cent, and sometimes as much as 6 or 7 amount is so minute that the author has never estimated per cent. The highly soluble salts, such as the salts of it. Frequently, however, it exists in the form of sulphide potash, do not affect the charcoal, and only annoy the refiner of ammonium, a compound which greatly damages sugar by accumulating in the syrups; but the sulphate of lime is run through it. Such char should be well washed and re- detrimental, owing to its comparative insolubility, and to the burned before being used. The washing removes common fact that it is readily absorbed from the sugar liquor by the salt, ammonia, and the sulphide of calcium which is likely charcoal. It may be removed, however, by copious washing to be present if the char has been overburnt. The last- and boiling, and it is even removed in solution by washing mentioned substance is due to the decomposition of the with weak sugar liquors. Such charcoal is sure to have its sulphate of lime, and acts injuriously on the sugar. Sul sulphate of lime increased if it be washed with water natuphuretted hydrogen is also given off from overburnt char- rally containing that substance in large quantity. The coal when treated with water or acid. A sample of new author stated that he had analysed charcoal containing 24 char gave 08 per cent of sulphuretted hydrogen on treat- per cent of the salt, and that the usual amount in old char ing it with hydrochloric acid. Combustible gases are fre- is from 1 to 4 per cent, but that in extreme cases it may be quently given off by both old and new char, and sometimes present in Clyde charcoal to the extent of 1 per cent. The they form explosive mixtures with the air of the cisterns. carbonate of lime present in some hard waters is also absorbed by the charcoal. Speaking of the mechanical properties of animal charcoal, Dr. Wallace said that he had long regarded the bulk occupied by the char as compared with its weight as a property of great importance. He stated that a ton of new and dry char fills a space of about 48 or 50 cubic feet, while a ton of old char may fill no more space than 40, 35, 30, or even 28 cubic feet, the apparent density of dry charcoal thus becoming sometimes nearly double what it was. But the absolute specific gravity of old and new charcoal varies but very slightly. That the charcoal rapidly diminishes in bulk while the real gravity remains practically unaltered is a point of great importance, and one to which the author thinks he was the first to direct the attention of sugar refiners. The inference is that by frequent re-heating, the particles of charcoal become smaller owing to the diminution of the pores; hence the apparent gravity of char gives a ready and certain indication of its value in sugar refining. From experiments made by Dr. Wallace, a specimen of new char lost as much of its porosity by burning in a covered crucible during eleven hours as it would have lost by re-burning about one hundred times in a sugar-house. He is of opinion that the porosity of the charcoal is diminished by a sort of agglutination of the particles of phosphate of lime during the reheating. New charcoal will hold from 80 to 100 per cent of water, and is made perceptibly wet with 20 per cent of water, while old charcoal (two or three years in use) will only hold from 30 to 45 per cent., and is made perceptibly wet with only 5 per cent of water. These facts prove that the pores become either smaller or less numerous as the charcoal is used, and point to the conclusion that, to keep animal charcoal in the most efficient state, it should be reburned in such a way as to lessen the porosity as little as possible. Dr. Wallace finds that although the action of heat is the main cause, it is not the only one concerned in producing an increase in the apparent gravity of the charcoal. The The re The author briefly considered the offices fulfilled by the various ingredients of the charcoal. Animal charcoal has great power of absorbing gases, colouring matters, and such mineral salts as are but slightly soluble in water. moval of colouring matter is the chief object in view; but gummy and other extractive matters have also to be removed. Animal charcoal extracts them both with equal facility. The author finds that it readily absorbs ordinary egg albumen and gum, and he thinks that the circumstance that each of these bodies has an insoluble modification may have something to do with their absorption by the charcoal. Iron is readily removed from sugar liquors by passing them through a cistern of new char. It is the nitrogenous carbon which is the most powerful decolourising ingredient of the char, for if the char be burnt perfectly white, on the surface and without, it does not remove the slightest trace of colouring matter. This fact the author has demonstrated by actual experiment; it is with him no mere opinion. The highly porous carbon is not the only useful ingredient, although it is essentially the decolourising agent. Carbonate of lime is also of use in neutralising the small proportion of free acid present in almost all sugars except beet; and it is still more important in neutralising the lactic and other acids formed in the weak liquors, by a process of fermentation which it is difficult to prevent. Hence charcoal deprived of its carbonate of lime is objectionable, and its use is certain to produce sour liquors and give rise to the presence of iron in the low-class sugars. As the water of Greenock and Glasgow contains only traces of carbonate of lime, the quantity of that salt naturally present in charcoal gradually lessens, until in pretty old char it is sometimes reduced to about 14 per cent. In refineries conducted on scientific principles the amount is never suffered to fall so low. If it falls below 24 per cent, sour liquors are sure to follow. When very hard water is used, the carbonate of lime either decreases very slightly or it increases, and sometimes even to an alarming extent, as in the continental beet refineries, where the evil is a very serious one. Dr. Wallace referred to the various methods-especially those of Beanes and Gordon-for getting rid of any excess of carbonate of lime in the charcoal; and then spoke of the inconvenience attending the use of animal charcoal in sugarrefining, owing to its oxidising influence upon the organic matters extracted by the char from the sugar, and to the alteration of the nitrogenous compounds by means of which fermentation is induced, and ultimately organic acids are formed at the expense of the sugar. These acids make the washings sour and putrid, and a necessary and evil result of that is that they decompose sulphide of calcium or sulphide of iron in the charcoal, and dissolve carbonate and sulphate of lime and oxide of iron; then, as the washings are either thrown back amongst the other products of the refinery, or mixed with a fresh lot of raw sugar, they occasionally cause an immense amount of mischief. The author said that, owing to its importance, this department of sugar refining had occupied a good deal of his attention, and he claimed to have made known to refiners the means of entirely preventing such injurious results as those referred to. His method is as follows:-While the liquor is on, the char cisterns are kept at a temperature of at least 150° Fahr., so long as the liquor is strong, to prevent fermentation. Then the water used for washing down the sugar is to run on quite boiling, and this is done with all the washings which are to be preserved. When these directions are attended to, there is no difficulty with sour washings, or with the presence of iron in the low-class sugars. The char should ultimately be washed with boiling water for 10 or 12 hours, or even boiled with it. The author concluded with a detailed account of the modes of re-burning charcoal, and of the good and bad qualities of the different kinds of re-burners now in use, and suggested the directions in which improvements might be made. An interesting discussion followed, and various questions were asked and answered in reference to the condition in which the nitrogen exists in the charcoal, and in reference to the use of blood and clay, soot and clay, and gluten charcoal, in sugar refining. On the motion of the CHAIRMAN, a hearty vote of thanks was accorded to Dr. Wallace. ROYAL INSTITUTION OF GREAT BRITAIN. Weekly Evening Meeting, Friday, March 13, 1868. "On the Probable Exhaustion of our Coal Mines," by W. STANLEY JEVONS, M.A., Professor and Cobden Lecturer on Political Economy in Owens College, Manchester. I. The coal raised from the coal mines of the United Kingdom in the year 1866, amounted to more than one hundred million tons (more exactly 101,630,544 tons), according to the excellent returns published by Mr. Robert Hunt, of the Mining Record Office. Reflecting upou the full significance of this fact, it may be asserted : I. That the coal trade of this kingdom is the greatest trade, in regard to the bulk and weight of the commodity, ever carried on. 2. That every pound of that vast quantity of coal may be regarded as a pound of the most intrinsically useful and valuable substance ever discovered. 3. That the power and usefulness of coal is felt in every branch of industry, and in almost every operation which we carry on. 4. That Britain possesses the aid of this most invaluable substance in an altogether peculiar degree: and 5. That we cannot hope to stand very long in this most happy position. II. So vast a quantity as 100,000,000 tons cannot be represented to the eye or mind. Its bulk is 30 times as great as that of the greatest single work of human hands, the Pyramid of Cheops. Greater quantities of commodities are brought into British ports at present, than are recorded in the history of any nation, and yet it would take more than seven times as many vessels as those which enter our ports in a year to carry the quantity of coal we use. More than half of the whole carrying power of the railways of the United Kingdom, devoted to goods traffic, is occupied in the conveyance of coal. So far as we can judge from returns, which do not always distinguish the kind of goods carried, the goods traffic of the railways of the United Kingdom in 1865 was as follows:General Merchandise* Minerals. Total. Coal and Coke...... Total...... TONS. 36,800,000 18,300,000 55,100,000 59,500,000 114,500,000 It III. This vast trade in coal can only be accounted for by considering the wonderful qualities with which coal is endow ed. It is the mainspring of our material industry. may be called the real Philosopher's Stone, which supplies us cheaply and plentifully with everything that can conduce to the service of man. This extreme usefulness of coal is due 1. To the enormous power which is latent in it, and is brought forth when we burn it; 2. To the fact, now so clearly revealed by science, that force is the key to all the changes of matter. By aid of the mechanical equivalent of heat, we can ascertain that good coal contains latent force sufficient to raise its own weight 11,422,000 feet, or about 2100 miles against the force of gravity. The coal raised in 1866 may further be calculated to contain force equal to that which would be exerted by 530,000,000 horses, or 2,650,000,000 men, working eight hours a day for 300 working days in the year. IV. This vast power is turned to use in an indefinite multitude of ways, which may thus be rudely classified. CLASSIFICATION OF THE USES OF COAL. (1.) AS SOURCE OF HEAT. 1. For Household Use.-Warming and ventilating houses, churches, public buildings, &c. 2. For the Alteration of Cohesive Condition of Substances.-Melting and casting of metals; softening and forging of metals-the blackmith's fire. Manufacture of glass, bricks, earthenware, &c. Boiling salt, soap, &c.; brewing distilling: drying substances. Electric light-house illumination. Tar, pitch, naphtha, lubricating oils. It is only by thus collecting together the multitudinous uses of coal that we can gain an adequate idea of its importance to us and the certainty that its use will extend. V. Comparing, now, the present yield of coal (100,000,000 tons anuually) with the quantity which Mr. Hull believes to lie in these islands, within 4000 feet of the surface and in workable condition (83.544,000,000 tons), we find that we might continue to consume coal at our present annual rate for 835 years at least; but when we remember that our consumption has increased by 36 millions in the last twelve years (from about 65 millions in 1854 to 101,000,000 in 1866), and that the causes of increase still continue in existence, we cannot attribute any importance to the above calculation. There is no appearance that steam navigation or railways have at all approached their full development in this country; while in the steam plough, in schemes of steamdrainage or water-supply, the employment of steam-produced hydraulic pressure, in the use of small gas-engines in workshops, and in a multitude of other ways, we have some indication of the increased future demand for coal. VI. Economy, it may be pointed out, does not tend to reduce the industrial consumption of coal, but acts in the opposite direction: by increasing the profitableness of coallabour, it extends its use. Almost every improvement in the engine for the last century and a half has been directed to economising the consumption of coal; and yet the use of the engine and the quantities of coal consumed advanced pari passu with its economical performance. It is altogether irrational to argue that progressive economy, which has coexisted with and been the partial cause of advancing consumption in the past, will have the opposite effect in the future. VII. As regards the law of increase of coal consumption. both experience and theory lead us to believe that the increase takes place in a geometrical series, by multiplication rather than by mere addition. The following numbers will illustrate the difference in question: Arithmetical Series, increasing by addition. 12345 6 7 8 Geometrical Series, increasing by multiplication 1 2 4 8 16 32 64 128 The following table will show that when we can get accurate statistics of the consumption of coal we find the increments indefinitely increasing, in the manner rather of a geometrical than of an arithmetical series. It is impossible to view, without some degree of alarm, so rapid an increase of the coal trade as the preceding figures indicate. Without doubt our production will advance to 200 millions before very many years are past; and the alarming calculation may be made that if we went on increasing our production of coal for 110 years as rapidly as we have done during the last 12 years, our coal seams would be worked out to a depth of 4000 feet. But such a supposition is put forward, not as a serious possibility, but as a reductio ad absurdum. The conclusion to be drawn from it is simply that the nation cannot possibly progress in material wealth for 110 years more as rapidly as it has done in the present century. The limited extent of our coal-fields would not allow us to go on increasing the draught of coal as lavishly as we have done. But it is the very necessity of changing from a highly progressive to a less progressive or stationary condition, that is most grievous. Population and production, when once set in motion, move with a certain impetus, and it is the check to such motion which is distressing and threatening. VIII. The subject wears a more serious aspect still when we consider the coal resources and production of other countries as well as our own. According to the latest returns which are at hand, it would seem that the total known produce of coal in the world is thus distributed over the chief nations: Increase in fifty 1 5,119,887 years. Tons. 212,100 260,600 410,300 2,539,883 5,696, 170* 1863 The above and other statistics quoted in the 'Coal Question,' Chapters IX. X. and XI. show that our industry grows by multiplication, and by multiplication at a rising rather than at a falling rate. The temporary depressions of trade which occur at intervals may sometimes seem check the rapidity of this increase; but we have only to wait a year or two to see our industry advancing again with growing strides. to No statements of the total amount of coal produced in this * Increase as for fifty years, if continued at same rate as during the thirteen years experienced. The Coal Question: an Inquiry concerning the Progress of the Nation, and the Probable Exhaustion of our Coal Mines." By W.S. Jevons, M. A. 2nd ed. revised. London, 1866. (Macmillan.) Ireland...... Total...... It would appear then that of the total known produce of coal in the world we raise considerably more than half (57 per cent), although we form probably not more than one in forty of the population of the world. If to our own coal produce we add that of the United States and our colonies, we may conclude that the Teutonic race enjoys 73 per cent, or almost 3 parts out of 4, of the coal raised. It is hardly possible to over-estimate the forces acting in our favor which are represented by this partial monopoly of the most powerful material agent of civilization. I am kindly informed by Mr. Hunt that when the returns of the consumption of coal in 1867 are completed, the total will probably amount to 104,000,000 tons, showing continued increase in spite of the depression of trade. 6. The exhaustion of our mines, as it will probably manifest itself within the next hundred years, will consist not in any stoppage of supplies, but an increase of cost, and the impossibility of increasing the consumption each year as at present. XI. At some future time, then, when coal will be even a more useful agent than at present, we shall stand in a position of comparative inferiority. For such a time we can best prepare ourselves, not by short-sighted restrictions on the consumption or evaporation of coal, but by freeing the nation from its burdens of debt and ignorance and pauperism. We have many great tasks to perform, which can only be undertaken with a fair hope of success when the nation is in a state of high prosperity and progress. It will be too late to think of such great undertakings when our progress is checked, and the pressure of population and the want of employment are grievously felt. It is in a period of free expansion like the present that we can alone take any effectual measures for raising appreciably the standard of education, comfort, and morality of the people; and if we do not use the abundant wealth which our coal resources now afford us to fulfil such duties, we undoubtedly misuse it. CHEMICAL SOCIETY. Thursday, May 7. IX. It is continually suggested, indeed, that before coal is at all likely to be exhausted, some substitute will be found for it, and appeal is made to some old proverb, like "Neces- Dr. Warren de LA RUE, F.R.S., &c., President, in the Chair. sity is the mother of invention." But it requires very little philosophy to see that the proverb is very partially true. We THIS meeting, as is usual on the special occasions set apart live in a chronic state of necessity and difficulty, and the for lectures, was exceedingly well attended, and several visigreat discoveries which we enjoy are but so many exceptional tors honoured the Society with their presence. Mr. E. instances in which we have been unexpectedly relieved from Dowson was formally admitted as a Fellow, and Mr. Thomas labour and evil. We have no real ground for supposing that Bournes, Teacher of Chemistry, 47, Rigby Street, St. Helen's, when one exceptional advantage is withdrawn from us, anLancashire, was duly elected. The names of candidates other will immediately be extended to us. read for the first time were Mr. William Bowyer Miller, Assayer, Royal Mint, Sydney; and Mr. William Hustler, Mining Engineer, Rosemerryn, Falmouth. The favourite notion that electricity will be the future source of power is entirely fallacious; for the coal-driven engine moving the magneto-electric machine is now the cheapest source of electricity, and by gradual improvements, such as that in Mr. Wilde's machine, coal will become a still cheaper source of electricity. Even the elements of the electric battery have always been practically furnished by the reducing power of coal. If coal then become, as there is every reasou to suppose it will, a cheaper and cheaper source of electricity, it is obviously absurd to suppose that electricity should supersede the power of coal. It is conceivable, indeed, that in the course of ages some wholly new source of power might be discovered; but there is no reason to suppose that this island, which forms but the one four-hundredth part of the total land-area of the globe, would be as richly endowed with the new source of power as it is with coal. If the sun's beams are in the future to be the direct source of power, it is the plains of Africa or of Australia that will be the seats of industry and not this cloud-obscured Isle. X. The conclusions we must come to on this subject are then as follows: 1. The power of coal is extending itself and making itself more widely and deeply felt every day. It is more and more taking the place of wind, horse, or manual power, and is becoming the universal assistant. 2. We are naturally led every day to extend our consumption of so invaluable a substance, and experience shows that the more we use the more extensive are our augmentations. 3. Our consumption is already commensurable with our total supply; that is to say, we can form some notion how long our supply will endure with a stationary consumption. 4. As this consumption increases by multiplication, our national life becomes shortened, and it is apparent that the increase cannot go on very long at the present rate. 5. The moment we are forced to draw in, other nations, possessing far more extensive fields of coal compared with their annual consumption, will be enabled to approach and ultimately to pass us. Mr. C. W. SIEMENS, F.R.S., delivered a lecture "On the Regenerative Gas Furnace as applied to the Production of Cast Steel." The lecturer announced himself to have been a pupil of Wöhler, and said he was prepared to estimate highly the value of chemical science in directing the studies of the engineer and electrician. The regenerative gas furnace, which has during the last few years been applied to the manufacture of iron and glass, and is destined to play an important part in other chemical operations, is the joint invention of Mr. Frederick Siemens and the lecturer. It was described in 1862 by Professor Faraday, and formed the subject of his last public lecture in the Royal Institution. Before proceeding to enter upon the discussion of the furnace itself, and its peculiar details of construction, Mr. Siemens briefly sketched the properties and modes of preparation of cast steel. This product was defined as being "a compound of iron and carbon, possessing the remarkable quality of becoming exceedingly hard when heated and suddenly cooled." The proportion of carbon determines its temper, and the following table, which was shown in the form of a diagram, indicates the average composition of steel of different quali ties |