NEWS

, 1873

THAT sodium sulphide was so formed the author first found by the passage of coal-gas over sodium chloride at a red heat. Concluding that its formation depended upon the presence of sulphuretted hydrogen in the gas used, experiments were made in which pure sodium chloride was exposed to the action of washed and dry sulphuretted hydrogen, at various temperatures, for periods varying from ten minutes to three hours. Sodium sulphide was always formed in amount varying and equal to from 093 to 15 per cent of the sodium chloride used. The temperature most conducive to the formation of sodium sulphide was found to be one sufficient to thoroughly fuse the salt used; and the rate of the current of sulphuretted hydrogen must be rapid enough to carry off at once the hydrochloric acid set free. The sulphuretted hydrogen used was sometimes obtained by the passage of pure hydrogen over fused sulphur, but generally by the ordinary methods.

Other experiments showed that neither hydrogen nor sulphur produced sodium sulphide when transmitted over sodium chloride at a red heat. So that when it is formed by the action of sulphuretted hydrogen it must be the result of a direct reaction.

2NaC1+H2S=Na2S+2HCl.

More experiments are in progress, to decide whether this is the only and ultimate reaction that takes place; but from examinations of the gaseous products, the author inclines to the belief that it is not.

ON A NEW METHOD OF VIEWING THE

CHROMOSPHERE.*

By J. N. LOCKYER, F.R.S., and G. M. SEABROKE.

THE observations made by slitless spectroscopes during the eclipse of Dec. 11, 1871, led one of us early this year to the conclusion that the most convenient and laboursaving contrivance for the daily observation of the chromosphere would be to photograph daily the image of a ring-slit, which should be coincident with an image of the chromosphere itself.

The same idea has since occurred to another of us; we therefore beg leave to send in a joint communication to the Royal Society on the subject, showing the manner in which this kind of observation can be carried out, remarking that although the method still requires some instrumental details, which will make its working more perfect, images of the chromosphere, almost in its entirety, have already been seen on several days during the present month and the latter part of last month.

The image of the sun is focussed on a diaphragm, having a circular disk of brass (in the centre) of the same size as the sun's image, so that the sun's light is obstructed, and the chromospheric light is allowed to pass. The chromosphere is afterwards brought to a focus again at the position usually occupied by the slit of the

* A paper read before the Royal Society.

spectroscope; and in the eye-piece is seen the chromosphere in circles corresponding to the "C" or other lines. A lens is used to reduce the size of the sun's image, and keep it of the same size as the diaphragm at different times of the year; other lenses are used in order to reduce the size of the annulus of light to about

inch, so that the pencils of light from either side of the annulus may not be too divergent to pass through the prisms at the same time, and that the whole annulus may be seen at once. There are mechanical difficulties in producing a perfect annulus of the required size, so one -inch diameter is used, and can be reduced virtually to any size at pleasure.

The proposed photographic arrangements follows:

are as

A large Steinheil spectroscope is used, its usual slit being replaced by the ring one.

A solar beam is thrown along the axis of the collimator slit by a 37-inch object-glass, the solar image being made by a heliostat, and the sun's image is focussed on the ringto fit the slit by a suitable lens.

By this method the image of the chromosphere received on the photographic plate can be obtained of a convenient size, as a telescope of any dimensions may be used for focussing the parallel beam which passes through the prisms on to the plate.

The size of the image of the chromosphere obtained by the method adopted will be seen from the accompanying photograph, taken when the ring-slit was illuminated with the vapours of copper and cadmium.

ON THE SUPPLY OF PIG-IRON FOR THE BESSEMER PROCESS.*

By W. BAKER, Associate of Royal School of Mines.

THE Bessemer process has exercised so important an influence upon the iron and steel manufactures of England, and is such a bold innovation upon the ordinary metallurgical processes, that I may fairly assume a short paper upon its present condition will not be inappropriate for the discussion of the Rotherham Literary and Scientific Society. The opportunity of bringing out our thoughts upon some special subjects with which each of us may be familiar is a peculiar advantage of such meetings as the present. Without pretending to be teachers, or to speak with an authority not to be questioned, we may at least give a direction to other minds, which may result in not only the confirmation and strengthening of our own ideas, but also in some determinate action.

The Bessemer process, as you know, consists in forcing jets of atmospheric air through molten pig-iron, whereby certain combustible elements which are found in pig-iron are burned. The fuel thus made use of in the iron itself developes an intense heat, and all who have witnessed a Bessemer "blow" will agree that it is one of the grandest sights of our manufacturing neighbourhood. According to Hunt's Mineral Statistics in 1869, there were 57 Bessemer converters, with an aggregate capacity of 248 tons. The last return for 1871 give 89 converters, with a potentiality of 446 tons. Taking 5 charges a day, or 30 charges a week, this gives us 669,000 tons per annum, against 372,000 this enormous increase has had its effect upon the supply tons in the year 1869. It will be readily conceived that of the raw material. Let me then place together the figures denoting the production of pig-iron for the same years. In 1869, pig-iron, 4,970,206 tons; 1871, ditto, 6,627,179 tons: an increase of 33 per cent. Now, the question arises, how much of this pig-iron is used actually, The quotation in the market price lists of Bessemer pig and how much can be used for the Bessemer process? disclose the fact that there is a special quality of iron * A Paper read before the Rotherham Literary and Scientific Society.

suitable for this manufacture. In order to appreciate accurately this fact, I will dwell for a few moments upon the chemical reactions which take place in the conversion of pig-iron into Bessemer steel. Ordinary pig-iron may contain carbon, silicon, manganese, sulphur, and phosphorus; traces of other elements are sometimes found. For the Bessemer process, as well as for crucible caststeel, the absence of sulphur and phosphorus is essential, or at most they may be present in extremely small quantities. Now, in the Bessemer converter, silicon appears to have the greatest affinity for the oxygen of the air. That is to say, silicon burns first and produces the heat due to its chemical combination with oxygen. The product of combustion is in its pure state a white solid, infusible, except under the oxyhydrogen blowpipe. In the converter it combines with some oxide of iron, and forms the slag or cinder, but often balls of white pumicelike silica, covered with a thin case of iron silicate, may be picked out of the cinder. These seem to have been formed by the rolling or splashing of the iron over the silica as it aggregated upon the surface of the molten metal. During the combustion of the silicon a more intimate combination takes place between the iron and the carbon. That is to say, the grey pig-iron, in which flakes of graphite exist, crystallised out in the mass of the soft iron, becomes changed into what is known as white iron. The latter is a variety of pig-iron, in which the carbon is chemically combined with the iron. Spiegeleisen is a typical example of this kind of iron. And now the combustion of the carbon begins, the product of combustion being in this case a gas, and the blue flame of carbonic oxide becomes whiter, and the roar of the furnace increases to its maximum. If we suppose the blast to be continued beyond the combustion of the carbon, what would take place? The iron would burn; and often a brown smoke, which issues from the mouth of the converter at the end of the process, announces that this is actually the case. The metal also would become unmanageable by frothing. It is usual, therefore, to stop the blast when the flame drops, and to add a known quantity of spiegeleisen. This iron contains generally about five per cent. of carbon and nine to thirteen per cent of manganese. With this addition the charge is tranquillised, metallic manganese imparts fluidity to the metal, and seems to protect the carbon from being burned. This I conclude from the fact that the Bessemer ingots themselves only contain traces of manganese, whilst the carbon ranges about 0.5 per cent.

A word about sulphur and phosphorus. It seems that both these elements refuse to give up their combination with iron at the solicitation of torrents

of oxygen, as it exists in the air at the high temperature of the Bessemer converter, although both sulphide and phosphide of iron may be roasted at a low red heat, and these elements be nearly entirely removed from the oxide of iron which is left. The problem of eliminating phosphorus from metallic iron, leaving the iron in the metallic state, is one of the most pressing problems for solution by the metallurgical chemist. Most of the metals which are used in the arts are obtained first accompanied by certain impurities, and a general mode of refining them is to re-melt them with an oxidising flame, with or without the addition of fluxes. Copper is thus treated, so is lead, and it is instructive to compare the results with those obtained with iron. Copper, when melted under the circumstances mentioned, affords a slag, rich in fusible red oxide of copper, which is itself a flux, and melts readily with the oxides of other metals which may exist as impurities-only gold and silver of the ordinary metals will remain unoxidised. Now let us consider the refining of lead by a similar process. The same removal of impurities takes place, but besides gold and silver we have a certain proportion of copper which refuses to be oxidised, but rather concentrates in the metal if the process is continued. Plainly other chemical reactions must be sought for its removal, and I am pleased to observe i

that my own labours in this direction have been acknowledged by Dr. Percy in his third volume, which treats of lead. The successful solution of the problem in this case was afforded by the property of copper alloying with zinc, which alloy forms a less fusible mass, that can be removed from the surface of the metal in which it floats. If we treat iron in a similar manner, we get a slag or cinder composed of oxide of iron and silica. The process I am considering is the puddling process, which in the first stage may be looked upon as an analogous refining process. The silicon oxidises first, then the carbon, and if we would keep the decarburised iron fluid, it is quite possible that at the expense of some of it the comparatively small amount of sulphur and phosphorus which makes the grand distinction between good and bad pigWe iron might yet be eliminated. are, however, stopped in the process of refining, i.e., the removal of impurities by oxidation-by the infusibility of iron deprived of carbon, and the charge is balled up and taken to the hammer for the production of wrought-iron. What I wish to point out here is that phosphorus in iron is analogous to the copper in lead; both resist oxidation to the last. The Bessemer process affords no help, the higher temperature at least might give the opportunity for the experiment. I mean that it would be worth while to see whether by continuing the blast at the expense of the iron as fuel a proportion of phosphorus to the extent of, say one-tenth per cent in the original pig-iron might not be eliminated. If this fail, we can at once and for ever give up the oxidation process for the removal of phosphorus. In puddling, it is true, a certain amount is removed, and the able paper on the Danks furnace, by my friend Mr. Snelus, of the Royal School of Mines, points to the probability, if not to the fact, that phosphorus in iron is oxidised by pure oxide of iron at the temperature of the puddling furnace. This certainly suggests the injection of metallic oxides with the blast, although the fatal infusibility of the decarburised iron is not favourable to the experiment. Mr. Isaac Lowthian Bell, whose labours as a scientific manufacturer cannot be too highly commended, has made some significant remarks on this subject. He says, "The limit to the production of Bessemer pig is the want of ores free from phosphorus." This may be correct, and so firm may be the grip that phosphorus holds on iron, that breaking up the bonds that bind them together may defy the skill of our scientific men; but it may be well to remember that the yearly make of iron from Cleveland stone alone contains about 30,000 tons of phosphorus, worth for agricultural purposes, were it in manure as phosphoric acid, above a quarter of a million, and that the money value difference between Cleveland and hematite iron is not short of four millions sterling, chiefly due to the presence of this £250,000 worth of phosphorus. The Pattinson process does not leave one part of silver in 100,000 of lead, the Bessemer converter robs iron of almost every contamination except phosphorus, but nine-tenths of this ingredient is expelled by the puddling furnace. It may be difficult, but let it not be supposed there would be any surprise excited in the minds of chemists if a simple and inexpensive process for separating iron and phosphorus were made known to-morrow, so that only one of the latter were found in 5,000 of the former. Analyses of the best Bessemer pigs give the following amounts of phosphorus, viz. :-0'014, 0'01, and o'016 per cent. I select from analysis of Bessemer steel the following:-English make: 0.025, 0'033, 9'032, 0·026; mean, o'029 per cent. of phosphorus. German make : 0132, 0°134, 0'093, 0'041; mean, o'10 per cent. of phosphorus. It will be noticed from the foregoing quotation that Cleveland pig-iron is contrasted with hematite iron. The distinction is this. Hematite iron produced from an ore of iron called hematite is sufficiently free from phosphorus to produce an iron suitable for the Bessemer process. Cleveland iron may contain from 0.5 to 1.5 per cent of this element.

The important question which justifies the title of my paper is this-What iron ore and how much iron is

silicates seem to have been held in special favour, since they repeat themselves, with some modifications, in several places. Lime, either alone, or with some subsequent chemical alteration into carbonate, sulphate, or sillicate is claimed ; or plaster-of-paris or hydraulic cement are used directly. Clay must also be named. Among organic substances may be named pitch, coal-tar, resin, the Trinidad bitumens, asphalt, petroleum residues, dextrine, glue, Grahamite, &c., while as accessories, employed either to assist cementation or combustion, we have sawdust, chaff, flour, blood, cow-dung, starch, sand, saltpetre, and other substances too numerous to mention. Comparatively few of these processes have ever reached a public trial, as indeed few deserve it, and of those which have received attention, none have been more than indifferently successful, either from inherent deficiencies or from commercial reasons. We give a brief survey of some of the more important processes.

For a number of years the bituminous or semi-bituminous waste from the mines of Germany, France, and Belgium, has been to a considerable extent successfully utilised by mixing with it from 15 to 30 per cent of ordinary moist clay, and pressing this plastic mass into forms of any desired shape and size. The product thus obtained, though of inferior heating quality, still secures a ready market, owing to the high price of coal in the countries named, where it finds employment not only for household purposes but also for steam generation. Quite recently a similar process, by which the percentage of cementing clay is reduced to a minimum, has been brought out in America by a Belgian engineer familiar with the methods employed abroad. His plan, according to description, is to employ about 7 per cent of clay with the dust, and, after thoroughly mixing the materials, to bring the mixture into a pressing machine, where it is pressed into cylindrical forms of convenient size under considerable pressure. In order to protect the product from the disintegrating effects of rain or dampness, the inventor passes the lumps thus formed through a bath of resin dissolved in benzine, obtaining in this way thin hide of resin upon the surface of the lumps, which effectually serves the purpose of excluding the water.

This plan, from its simplicity, aided doubtless by the favourable opinion expressed of its merits by a committee of the Franklin Institute, has received the favourable consideration of the Lehigh Coal and Navigation Company. The adandoned works of a former unsuccessful company, which will be named hereafter, situated at Nesquehoning, Carbon County, Pa., have lately been secured by the Lehigh Company, for the purpose of giving the plan a thorough trial. The expensive machinery of their predecessors has been, or is now, in process of being modified to suit the present plan.

The same inventor has laboured zealously in this field for a number of years in the South, having for some time successfully manufactured at Nashville, Tenn., an artificial fuel by the same general process from the Southern bituminous coals, until certain business complications conspired to raise the price of the waste to so high a figure that the manufacture was abandoned.

The other plans (employing a mineral cement) as yet made public include those using an alkaline silicate (water-glass), either alone or in connection with a chloride of calcium or magnesium, or both, an hydraulic cement, plaster-ofParis, &c. As far as the knowledge of the writer extends, none of these have yet passed through the ordeal of practice, and should this have occurred with any one of them it has simply resulted in a failure. All such attempts must prove unsuccessful, from the fact that either the combustible character of the coal waste is so considerably reduced by the mixture with it of from 10 to 20 per cent of non-combustible materials that the product can only be burned with difficulty, necessitating either constant attention or an artificial draught, or the cement employed fuses in the heat of the furnace, and, coating the cemented particles with a liquid glass, prevents the access of the

air to it, preventing its combustion, and, finally, forms an objectionable clinker. For reasons to be specified below, the writer is of the opinion that no process employing a mineral cement will ever be more than indifferently successful, not excepting the clay process, of which so much is anticipated.

It is well known that coal of any description, and especially when in the finely-comminuted condition of dust, if exposed for some time to the combined action of air and moisture, gradually deteriorates in heating quality. This deterioration is produced, first, mechanically, by the slow admixture with it of dust and dirt carried by the winds; and, secondly, by a slow process of oxidation, analogous to the rusting of iron, which infallibly attends the exposure of any readily oxidisable substance to atmospheric influence. From both of these causes, the heating quality of the coal waste is slowly reduced (or its percentage of ash, to state the case in other words, is slowly increased), and this reduction in quality grows greater and greater with the time of its exposure. With bituminous lump, Varrentrapp estimates, from careful experiments, that the loss of heating power, from chemical causes alone, may even reach 25 per cent, and, for purposes of gas production, 45 per cent. With anthracite lump, the deterioration from this cause alone will be far less than with bituminous; but, from both the causes named, it must be evident that, with the anthracite in form of waste, the deterioration must in most cases be considerable enough to gravely influence the success of any plan having in view its manufacture into artificial fuel. By the employment of dust from freshly mined coal, or of a judicious mixture of the old waste with the new, the difficulty from this source may be partially overcome; but no scheme having for its object the utilisation on a large scale of the vast waste heaps of the anthracite region, can afford to be blind to the objection here named, since it is mainly from more or less deteriorated materials that the product to be utilised must be obtained.

Instead, therefore, of employing in the cementation of the waste a substance incombustible in itself, and which directly adds so much to the percentage of ash, and still further detracts from the heating quality of the waste, the path seems pointed out to inventors to seek about for some cementing material which, being itself combustible, will improve the heating qualities of the poor waste, and which must be free from certain collateral objectionable features incident to the problem. This fact seems to have been recognised long ago, as the list of combustible cements given previously would indicate. Whatever of historical record there has come to our knowledge with regard to their trials, however, is equally unfortunate with the mineral cement processes. In some of the European countries only, have the attempts to employ coal-tar, pitch, resin, and kindred substances to bind the loose particles of dust into a coherent mass been successful. In America it has several times been essayed to apply such a process to the utilisation of anthracite waste, but all have signally failed.

Several years ago a company was formed with this object in view, by whom the extensive works at Nesquehoning, Carbon County, Pa., referred to in a former portion of this article, were erected. They employed a mixture of waste anthracite with coal-tar; this, after the most thorough mixture which could be attained (with the aid of heat), was pressed into suitable forms, and subsequently transferred to an oven, in which it was subjected to a baking process. From the testimony of several engineers, superintendents, and others who used it, it appears that the product, in spite of the increment given to its heating quality by the addition of coal-tar, was but an inferior steam generator. Whether the only partial carbonisation of the tar by the baking process allowed the offensive coal-tar odour to be perceived or not, is a contingency not known to us; but it will readily be granted that, unless this carbonisation was complete, the introduction of the product for the household was im