M BURGLAR-PROOF SAFE. ESSRS. MARVIN AND CO., of New York, have recently contrived a safe which they allege to be perfectly burglar-proof. It is shown in the accompanying engraving. The material of the safe is the well-known chrome iron, which is so hard, when melted and cast, that no tool can penetrate it. In form the safe is a globe, hollow, and resembling a spherical shell; the door, which fits air-tight, is ground to place. The door being built of wrought iron and the best hardened steel, cannot be chipped or drilled. The lock spindle is also made of hardened steel, and of tapering form, so that it cannot be driven in. greater, is still liable to more variation than is the power, the increased surface over which the gas case with the poorer gas; but the greatest instabi- passes after it is eliminated from the coal exposes lity is experienced when a mixture of poor and rich it to the chance of decomposition, and the consecoal is used. That this should be the case is very quent deposition of its carbon. That this goes on natural. In gas made from the character of mate- to a very great extent is evident, from the amount rial first referred to, we have the least amount of of solid carbon, or graphite, found on the inner surmechanical mixture, owing to the small quantity of face of the retorts. In through retorts this deposiolefiant gas or hydrocarbon vapours present. With tion is due mainly to two'causes; in the first place, the use of coals, on the other hand, rich in volatile in charging the retort with coals either by the scoop hydrocarbons, as referred to secondly, we have a or shovel, the centre of the retort scarcely ever regreater mixture of poor and rich gas, and likewise eeives its due portion of coal, and as this part is an increased quantity of hydrocarbon vapours pre- always the hottest, it follows that the gas generated sent; the absolute illuminating power of the com- from the thinner stratum of coal is exposed to inpound gas is therefore liable to greater deteriora- tense heat, and a portion of it is speedily decomtion by the deposition of some of its light-giving posed, liberating the hydrogen and depositing the constituents. But with the description of material carbon, thus forming a deposit which rapidly inreferred to thirdly, the greatest depreciation may creases and soon renders the retort useless, unless be looked for. The gases generated from the mix- precautions are taken from time to time to remove AT a meeting of the Society of Engineers, held one with the other. Tht a feeble com- the carbon. Another cause of this deposit is the bination, the one with the other. The hydrocarbon want of uniformity in the pressure in the two vapours are merely held in suspension, and do not hydraulic mains; a slight resistance in one main enter into union with either of the gases; the or the other causes the gas to take the course offerslightest obstruction, or the lowering of the tem- ing least obstruction, and as the particles of gas perature, soon destroys this slender connexion, and thus pass over a larger amount of heated surface, the result is the loss of a very considerable portion they are exposed to the greater risk of decomposiIt is tion. Several expedients have been suggested to of the illuminating elements of such gas. strange yet true that this last process of manufac- remedy this evil; one is to use a valve to each asturing by mixed material is the one very generally cension pipe, so as to dispense with the dip pipe adopted to meet the requirements imposed by the when the retort is working; another is to have only Legislature as to the quality of gas. Judging from one hydraulic main, placed over the centre of the recent proceedings in Parliament, it appears very ovens, and both mouth-pieces connected to it by a probable that a higher standard of illuminating single dip pipe. nies, especially those which supply the metropolis. power will be imposed upon a number of gas compa SOCIETY OF ENGINEERS. on Monday last, Mr, Baldwin Latham, President, in the chair, the following paper was read on Modern Gas Works at Home and Abroad, by Mr. Henry Gore, C.E:-Among the varied applications of scientific discovery to the purposes of daily life during the last century, few, if any, have attained greater importance than that which relates to the manufacture and application of coal gas. Scarcely a city, town, or village, of considerable size, in this country, or on the Continent, or even in the United States of America, remains unsupplied with this almost indispensable agent, in our industrial and social existence. Its use is rapidly extending in more remote regions, for strange as it may appear, there are many peoples and communities who, though persistently resisting useful applications of practical science as dangerous innovations, are yet eager to avail themselves of the use of gas as a source of artificial light and heat. Even religious prejudices of the most obstinate character have succumbed to this desire, and we now behold the Christian Church, the Mosque of the Mahometan, the Hindu, Budhist, and even the Chinese Temple, each illuminated by this simple yet beautiful light. It is not the intention in the present paper to enter into an elaborate description of the dimensions or plan of the buildings, or the character and arrangements of the machinery and apparatus that constitutes a modern gas works. The author proposes to deal rather with those leading principles of construction essential to the production of the greatest amount of light, from a given quantity of materials employed; and to the situation in which the manufacture may be most successfully con ducted. combustion. Adopting this plan, it will be requisite, at the outset, to consider briefly the important question, "What is the chemical constitution of coal gas? In the absence of any other well-supported theory, it is the generally received opinion that the light afforded by this gas is due to the amount of solid carbon incandescent in the flame at the moment of The two most important gaseous compounds of hydrogen and carbon, are marsh gas, or light earburetted hydrogen, and the other olefiant gas. The composition of the first is represented by the symbols CH 2, and consists by weight of 75-4 of carbon, and 24-6 of hydrogen. The composition of the second is represented by the symbols C 2 H 2, and consists of 86 parts of carbon and 12 of hydrogen. The permanently gaseous constituents of all coal gas consist essentially of combinations of these two fluids or compound gases; but experiment shows that it is not a chemical union that is formed between them, but simply a mechanical mixture that takes place. Thus some coal gas of low illuminating power consists principally of marsh gas, with a very slight proportion of olefiant gas; other gas, of high illuminating power, contains an excess of olefiant gas. But the value of gas as a source of light is not due entirely to its gaseous constituents, for it almost always contains a certain quantity of vapours, more or less rich in carbon, and therefore extremely valuable as light-giving agents. It should be the great object of the gas manufacturer to produce and retain the richer gas and light-forming vapours, up to the moment of combustion in the burner. In endeavouring to accomplish this he meets with many difficulties. An important element in the chemical character and the light-giving capabilities of coal gas, depends on the materials used for its generation, and the obstructions it meets with in its passage from the place of manufacture to the point where it is to be consumed. What is technically called a poor gas coal always yields gas of the most permanent character, and is the most uniform in its amount of illuminating power. With a coal rich in the constituents of olefiant gas, the illuminating power, though actually much The material of which the retort is made will exert a very important influence on the production of gas of high illuminating power. The high temperature at which clay retorts are worked, tends to produce a very large quantity of carbonic oxide and hydrogen, by the decomposition of the olefiant gas and hydrocarbon vapours. It is frequently asserted, that by the use of richer Cannel coals, the excess of non-illuminating gas is rendered highly carbons given off from the richer coal; but this is luminous, by becoming saturated with the hydroonly true to a limited extent, inasmuch as the mixture undergoes rapid deterioration, consequent on the liquefaction of a large portion of these hydrocarbon vapours. We now proceed to consider the operation of the In the earlier years of gas lighting, the illuminating power of gas was not regarded as a question of any great importance; the coal or material most easily or cheaply obtained was used, so that rich or poor gas was produced, just as the works happened to be nearest to ordinary or Cannel coal. And when opposition was raised against these existing comThe most important movement in this direction was panies, it was almost always on the ground of price. that which led to the establishment of the Great Central Company for the supply of the City of London. The two fundamental principles upon which this undertaking started, were a low price and a low standard of illuminating power. To carry these proposals into practice, required that the condenser, in the process of gas manufacture. By Works should be constructed upon a system involv- the term condenser, we usually understand the aping some important modifications and changes in paratus acting as a means of cooling or refrigerathe machinery and apparatus; and a process of tion, but this is only true in reference to its use manufacture was adopted, the main feature of which where the gas is of poor quality and of low specific was to obtain quantity, quality being only a se- gravity. In treating gases which are to possess condary consideration. The principle laid down in high illuminating power, it is not desirable to rethe case of the Great Central Company has been duce their temperature below 60deg. Under these more or less applied throughout the country, and circumstances, therefore, we must look upon the the result has been, that the constructive details of condenser as a separator and not simply as a refrigegas works have been carried out almost exclusively rator. The two forms of condensers most generally with a view to obtain the largest possible QUANTITY in use are the tubular, or series of pipes, and the of gas from the materials used for its production. annular. Whichever of these forms is adopted, a Furnaces affording the greatest heat, retorts ex-large extent of surface is indispensable, in order that posing the largest carbonizing surface, condensers the separation of the mechanical and non-chemical and scrubbers making the strongest ammoniacal impurities contained in the crude gas may be graliquor, purifiers of large capacity and surface for the oxide system of purification, monster gasholders, and last, though not least, street mains of the dimensions of small tunnels; these, and perhaps some other matters, are the concomitants of cheap gas, as inaugurated at the period above referred to. Subsequent events, however, have shown that at least one of the parties to the arrangement (the gas consumers) have become dissatisfied with their bargain. An agitation which originated some years ago still continues for a repeal of the condition as to quality, and the Legislature has so far interfered as to raise considerably the standard of illuminating power; the important question presents itself whether, in meeting this change, it may not be requisite to modify the present mode of constructing gas works, especially in those localities where mixed coals are used for producing gas of the quality required by these new regulations. A glance at the several sections of the retort settings will show the form and arrangements at present generally adopted. Fig. 1 shows the method of setting retorts adopted by Mr. Lowe, at the Chartered Gas Works; fig. 2 shows Mr. Jones' method at the Commercial; fig. 8 Mr. Evans' method at the Chartered Works, Westminster; fig. 4 is Mr. Methven's at the Imperial Works, St. Pancras; fig. 5 is Mr. Gore's arrangement at Valparaiso; and fig. 6 is Mr. Henderson's superheated steam retort. In large works, and with clay retorts, the system of through setting, with double mouthpieces, is unquestionably the most economical, botn as regards fuel and durability. But this arrange ment is open to grave objections. If the retorts are used for the generation of gas of high illuminating dual. The existence of napthaline may in many cases no doubt be traced, first, to the high temperature at which the gas is generated, and again to the too sudden reduction of the temperature by rapid and excessive refrigeration. It is a strange anomaly that so much care and labour should be applied to remove so many of the light-giving ecnstituents from the gas, and then to give back these elements by the use of costly, and in some cases dangerous appliances, in napthalizers, carburetters, and other high sounding and wonderful specifics. In the generality of works as now constructed, the gas, after leaving the condenser, is subjected to the process of washing, either by means of the old-fashioned wash vessel, or the more modern contrivance called the scrubber; the object in either case is still further to purify the gas from any remaining particles of tar, heavy oils, and ammonia. As the use of the washer has become almost obsolete, we shall confine ourselves to a few remarks on the action of the scrubber. Many very conflicting statements have been made in reference to the effect of water in removing some of the light-giving constituents from coal gas. Several chemists, who have the reputation of being oracles in these matters, have assorted that water exerts but a small influence in diminishing the illuminating power of coal gas. Some engineers, who certainly have an equal claim to consideration from their great practical experience, say, on the contrary, that water produces a very injurious effect. In the year 1860, the author of this paper, in his capacity of engineer to the Valparaiso Gas Company, was obliged to economize the use of Cannel coal on those works, and yet maintain an certainly be avoided, first, because it is a dishonest illuminating power of nineteen candles. To effect thus causing a constant decomposition of the sul- at the works. The difficulty of getting rid of the residual products from gas manufacture, particularly ammoniacal liquor, has led to the plan of obtaining a stronger solution of the salts by passing the liquor over and over again through the scrubber. The advocates of this process claim for it, among other advantages, that more of the hydrocarbon vapours are retained than when the gas comes in contact with pure water; and it is possible that this may be to some extent true, because, although each time the liquor comes in contact with the gas it takes up some particles of hydrocarbon vapour, or it may be some portion of the olefiant gas, yet, as in the succeeding stages of its passage, it absorbs more of the ammoniacal gas, the hydrocarbons are to some extent liberated, and are taken hold of by the gas in exchange for the particles of ammonia it has given up; but whether this latter supposition is correct or not, it is certain that the use of a large quantity of water in any form is prejudicial to the light-giving elements of coal gas. In the arrangement of the apparatus of a gas works, the next in order to the purifiers is the station meter, but as this machine exerts no direct influence on the process or products of manufacture, the author passes on to consider the means adopted for the storage of gas. On the first establishment of gas works some very absurd opinions were expressed as to the form, construction, and capacity of gas holders. The restrictions proposed as to the dimensions of these vessels are certainly very amusing when recalled and contrasted with the monster creations of the present day. The demand for gas, consequent on the reduction of price, has led engineers to construct gas-holders, the capacities of which are measured by millions, instead of hundred of thousands of feet, as was the case formerly; attempting to answer satisfactorily the ever-recurring question of economy. It must be admitted that the larger the gas-holder the cheaper its cost at per thousand feet of its contents; but it is a question for serious consideration whether, as a matter of safety, these enormous depositories are not open to grave objections. So long as the quantity produced in the course of manufacture was the essential object of our manipulations, the effect on the quality of gas by its storage was only of secondary importance; but if, as we are by recent events led to believe, a much higher standard of illuminating power is to be imposed on gas manufacturers, the advantages of these enormous gas-holders may not prove so obvious in the future as they appear at present; for besides other reasons that will suggest themselves to the mind of every competent gas engineer, the fact that the storing of gas (especially such as contains any considerable amount of hydrocarbon vapours), is sure to result in an appreciable diminution of its illuminating effect is, of itself, a good ground for objection against the construction of what the author cannot help calling, injudiciously large gas-holders. Before leaving this part of his paper, the author might have been expected to say a word or two in referonce to the mode in which some of these vessels are constructed, but as these are purely mechanical details, and do not in any way affect the condition or quality of the gas, he will reserve his remarks upon this subject, until offering a few observations upon the peculiarities necessary in the construction and arrangements of gas works in foreign countries. Nour THE PARSONS' GUN As "Naval, Military, and Gunnery Items," last week, we inserted a paragraph to the effect that Mr. Parsons' converted gun had split at the thirty-third round of its endurance test. this appears to be not quite correctly put, we may observe that the gun has fired 165 rounds-163 with 30lb. of powder and 150lb. shot, and two proof rounds with 371lb. of powder and 150lb. shot. It is only the cast-iron casing that is cracked; the tube is perfectly sound, but slightly enlarged, which is not surprising when it is remembered that this gun of 5 tons has been firing the battering charges of the 9-ton or the service charge of the 12-ton service wrought-iron guns. This result is considered most extraordinary, being more than any gun has yet accomplished of the same size; and it is a valuable experiment, as proving the perfect safety of these guns in failing by the gradual process externally when overtasked, by which due notice is given to the men serving the gun, and an explosive burst rendered impossible. THE HOWARD SAFETY BOILER. N our impression for December 6, 1867, we de scribed and illustrated the tubular boiler of Messrs. Howard, of Bedford, as erected at the Compressed Forage Works, Mile End. Since that time, Messrs. Howard have manufactured and put up a number of these boilers, which are giving every satisfaction. Amongst the latest examples, we may refer to two, which are now working at Messrs. Illingworth and Ingham's, timber merchants, Wellington-street, Leeds. They are, of course, tubular, commencing over the fire with a series of horizontal tubes, a vertical series rising from these joins to another horizontal series at the top, these latter and top of the former constituting the superheater. The bursting pressure of each of the tubes is at least 2,000lb. to the square inch, and tested to a bursting pressure of 500lb. to the inch. In the event of the bursting of a single tube, which is a very unlikely occurrence, no dangerous accident could ensue, the result being only equal to the opening of a valvo with a rush of steam and water into the heating chamber, a sudden lowering of the steam pressure, Thus the and possibly the extinction of the fires. elements of safety are complete in the boiler itself. The two boilers are each 35-horse power nominal, or collectively 70-horse power, and only occupy a space of 12ft. by 10ft. by Gft. 6in. Priming, the original evil connected with this principle of construction, has been entirely overcome, and the evaporative power of the boilers is excellent, 1lb. of coal evaporating 10lb. of water. A working pressure of steam can be generated from cold water in twenty minutes from the time of starting the fires. We, therefore, have here all the elements of a safe and economical steam generator-points of special importance in these days of accidents from explosions and dear fuel. In removing from gas its chemical impurities, lime is unquestionably the most appropriate agent, and, in all situations where it is possible to employ it, it should be used to the exclusion of all other substances. Considerations of economy, and cer- Before concluding the first section of this paper, tain sanitary regulations, have induced chemists the author desires to say a few words on the most and engineers to turn their attention to some of the favourable localities for gas works, and the means mesallic oxides as substances adapted for the pur- of distribution. In selecting a site for works, the poses of gas purification, and now by common con- following are among the most essential desiderata: sent certain oxides of iron are used as a substitute-Sufficiency of area, a low level, a good supply of for lime in most of our important gas works. The water, good drainage, and easy access. Even in action of this material is to remove the sulphuretted some modern works these important conditions are hydrogen, by the union of the sulphur with the sometimes most palpably neglected; as a general iron, forming the black sulphuret or sulphide of rule, however, they are complied with. In the iron. When the material is fully saturated, it is earlier times of gas engineering it was thought deremoved from the purifier, and on exposure to the sirable that the supply should be as near as possible AT the French Academy of Sciences the perpetual atmosphere undergoes a series of chemical changes, to the centre of the consumption, but modern prac-secretary recently announced that a newspaper had which result in the precipitation of the sulphur tice removes our gas works to remote distances, and recently revived an old story, to the effect that the and the re-oxidation of the iron, which again be some enthusiastic persons have even suggested the Academy was in possession of a considerable sum comes fitted to act as a purifying agent; in fact, removal of the manufactories to the centres of our bequeathed to it as a reward for any person who the process of revivification may be carried on coal districts. Wild as this proposal seems, it might might discover the quadrature of the circle. He, for months before the purifying power of the possibly be realized, if GAS and not LIGHT was the therefore, suggested the propriety of again publishmaterial is entirely exhausted. In construct-product to be supplied; but if the public demanding the decision the Academy came to in 1775, of ing purifiers for the oxide of iron process, a much GAS LIGHT, and not LIGHT GAS, then the proximity solutions that might be sent in of the following pronever more devoting the slightest attention to the larger superficial area is necessary than when of the works to the locality of the consumption must blems:-The duplication of the cube, the trisection hydrate of lime is employed. It is very ques-be a vital element in the economy of gas manufac-of the angle, perpetual motion by means of a mationable, the author ventures to think, whether ture. The longer the distance through which the chine, and the quadrature of the circle. It justified the practice of increasing the thickness of the gas has to travel before reaching the burner of the this course as regards the latter, by remarking that layers of the oxide is in all respects good, espe- consumer, the greater will be the loss of illumi- many weak-minded persons, utterly ignorant of cially when the material is partially spent. A very mathematics, and labouring under the impression objectionable system is now pursued in gas manuthat large sums were ready to be handed over to facture of disregarding the existence of carbonic them in case they succeeded in solving that problem, acid in gas. The reason assigned for this practice gular business and the interests of their families, and devoted their time to it, utterly neglecting their reis that the quantity is so small that its interference even occasionally losing their reason by following with the illuminating power of the gas is easily such a vain pursuit. compensated for by adding a little more Cannel in the process of manufacture. These petty adulterations for the sake of a paltry economy are unworthy the position of those who have the control of such important undertakings as our modern gas works. Another economic suggestion has been made, namely, the revivification of the oxide in the purifier itself, by allowing a portion of atmospheric air to be driven through the material along with the gas, nating power; hence it follows that a company (To be continued.) OF IMPORTANT ΤΟ ENGINEERS AND USERS STEAM MACHINERY.-Every Boiler should have Feed Pump independent of the Steam Engine. This is the Practice of the Leading Firms of Engineers, who are now using exclusively the Donkey Pumps manufactured by Alex. Wilson and Co., Engineers, Vauxhall Iron Works, Nine Elms, London, S.W.— [ADVT.] DOOR OF WAREHOUSES IN CANNON STREET. WAREHOUSE DOOR IN CANNON-STREET. at comparatively low rates highly skilled and really of the kind which we have in general use in Engartistic labour. In the matter of artistic design, land or Scotland, and, above all, those hideous in building or architectural castings, our brethren abortions which disgrace the good city of Glasgow, GLASGOW has beeno may call builders of Scotland, like ourselves, have till very recently yet we cannot but observe with pleasure that here cast iron work, the cheapness both of labour and been far behind the standard of German and metal, and the great fluidity of the iron consequent French productions of this class; but of late years, on its high percentage of carbon, having given as all who observe the tendency of most branches facilities for the production of light castings of English architetcure will acknowledge, there possessed in an equal degree by no other district in has been a most decided advance in the taste disthe world. Berlin, it is true, has the command of played in the design of those addenda to buildings a quality of pig even superior to that of Glasgow into which cast ironwork now so largely enters; for very fine castings, but in price for plain articles and although the common French street lamp, with she cannot compete with Scotland, though she has its highly classic contour, puts to shame anything and there, more especially where corporations and. aldermen have no chance of meddling, a better tone is creeping into the designs of almost all classes of fixed ironwork, both in our domestic and public architecture. The specimen of ornamental ironwork which we illustrate in the present number we have selected from some thousands of designs for various branches of architectural work in the possession of Mr. Macfarlane, of Glasgow, all of which have been produced in his drawing office, most of them being from his own tracings, and we doubt if anyone has done more than he has to improve the artistic treatment of a metal which, when its characteristic feeling is seized upon, is as suitable for the development of high art forms as any of its brethren. The door, of which we illustrate the design, is one of Mr. Macfarlane's latest productions, and is intended to form the entrance to his new warehouses, under the Cannon-street station, which will extend from the river frontage back to Thames-street. Anderson, of John Penn and Sons. These gentlemen, without following Dr. Paul through the chemical reasoning worked out in his report, have certified that the facts of consumption and evaporation on which his report is based, are correct, and those which actually were observed by them on the occasion referred to. REPORT. Practical Trial of Liquid Fuel on Board the "Retriever," October 23. Material Used.-Dead oil, weighing 10.5lb. per gallon. Method of Using the Oil.-Burning the vapour under pressure, according to Mr. Dorsett's patent. ON starting at 12.25 p.m., the level of the oil in the vapour generators was observed and noted, cressol, which contain, besides carbon and hydrogen, some oxygen, together with a variety of hydrocarbons, such as naphthaline, xylol, cumol, cymol, and perhaps others. According to the chemical composition of these substances, and on the assumption that the combustible carbon and hydrogen they contain will generate when burnt with just sufficient air for perfect combustion quantities of heat sufficient for converting respectively 11-359lb. and 41-895lb. of water at 60deg. into steam at 212deg. Fah. for each pound of carbon or hydrogen burnt, when allowance is made for the heat rendered latent by the evaporization of the water resulting from the combustion of hydrogen and for the waste of heat due to the furnace gas being discharged at a temperature 600deg. Fah. above that of the air supplied to the furnace for combussubstances, and the evaporative duty they are capable of effecting, will be as follows, for one pound weight of each: given rise evaporative power of practical consideration of the mode of testing such guns converted on this principle, Major Palliser has proposed the following proof and inspection, which has been adopted by the War Department: -An officer of some experience to be sent to the works at which the contract is to be carried out, in order to inspect each part before the gun is put together, as to material and manufacture. This is not to release the contractor from responsibility, as upon the final proof and inspection of the guns at Woolwich their reception or rejection would rest. The guns are to be tested by the water proof, and returned if any considerable leakage occur after proof, it being optional with the contractor to have from five to ten rounds fired to test the importance of the leakage. If after firing these rounds it is stopped, the gun is to be received, and the extra rounds charged to proof; but if still considerable, the gun is to be rejected, and the extra rounds charged to the contractor. No flaws or blemishes will be permitted in the powder chamber before proof; if they arise after proof, they must be dealt with as at present, and in cases where it appears desirable to fire extra rounds, the same method of charging these results is to be adhered to as in the case of water proof. Flaws, blemishes, coil marks, &c., in other parts of the bore are not to cause rejection unless very large and obviously dangerous, or clearly showing neglect in manufacture. The usual proof regulations in other respects to be adhered to. An extensive conver sion of the present cast-iron smooth-bore guns of the service into rifled guns, with linings of coated iron, has been approved by the Secretary of State for War, and it, therefore, becomes necessary to determine which of the many methods proposed from time to time by Major Palliser should be selected and adopted to guide the conversion of the guns in question. ROYAL HORTICULTURAL SOCIETY. THE following arrangements have been made by the Royal Horticultural Society for their exhibitions and meetings next year:-March 13. Show of hyacinths and spring flowers. At this meeting prizes to the amount of nearly £50, offered by the principal bulb growers in Holland, will be competed for; and Mr. William Paul, of Waltham-cross, will continue his exhibition of spring flowering plants. April 17.-Show of roses and spring flowers. May 8.-Show of early azaleas and spring flowers. During this month a show of zonal pelargoniums will be held, at which subscription prizes by the growers of these plants will be competed for. June 2 and 3.-Grand summer flower show. June 15.-Special prize show. June 29.-Great rose show. summer exhibition of flowering plants and fruits will be held at Manchester in July at the same time as and adjoining the Royal Agricultural Society's show. The fruit and floral and general meetings for election of Fellows, &c., will be held January 19, February 16, November 16, and December 21, and on the first and third Tuesday in 44.5 Therefore, the quantity of oil which had been consumed during the 4hr. 35min. was 134-75 × 2·55230·1375 gallons, and as the oil weighed 10.5lb. per gallon, the weight of oil consumed was 2416-44375lb. or 1.078 ton during the 4hr. 35min., the average rate of consumption being 527-6071b. (50-25 gallons) per hour, or 8.79341b. per minute. In order to estimate the evaporative duty obtained with the oil, the capacity of a portion of the boiler, corresponding to two points on the gauge glass, had been previously ascertained, and found boiler was at the higher one of these points, the to be 450 gallons, and when the water level in the feed water and blow-off cocks were closed, and the time observed which elapsed before the water level was reduced to the lower point, the engines being kept going meanwhile. The evaporation of this ing to the foregoing determination of the average 450 gallons of water occupied 36min., and accordrate of consumption, viz., 8.7934lb. per minute, the quantity of oil consumed during 36min. was 316-5621b. The pressure in the boiler was, on the average, 15lb., corresponding to a temperature of 252deg. Fah., and the rate of evaporation under these conditions amounted to 4500 316-5634 =14215lb. Reducing this ob- each month from March to October inclusive. DORSETT'S PETROLEUM FURNACE. HE following is the report of Dr. Paul on the E. Dorsett's system of burning liquid fuel, on board the steamship "Retriever," on a trip from Deptford to Coal House Point and back, on the 23rd of October, when the quantities of oil used, and of water evaporated, were noted and checked by Mr. T. R. Crampton, C.E., of Great Georgestreet, Westminster; Mr. Alexander Wylie, late of the Royal Mail Company's service; and Mr. H. During the trial very little smoke was produced, and during great part of the time there was none into the funnel ranged from 250deg. to 350deg. at all. The temperature of the furnace gas passing Cent. (=482deg. to 662deg. Fah.), or on the average about 572deg. Fah., and as the external atmospheric temperature was about 50deg. Fah., the waste of heat in the discharged gases corresponded to the increase of temperature to 522deg. Fah. above that of the air consumed in feeding the furnaces. For the purpose of arriving at some approximate estimate of the extent to which the result obtained in this practical trial correspond with the actual it to me desirable to calculate theoretically the amount of heat it is capable of generating, and the maximum effect to be expected from its application under the ordinary conditions obtaining in practice, upon the same principle which I have applied in the case of petroleum and shale oil. So far as the chemical nature of dead oil is known, it is a mixture of several substances, such as phenol and Evaporative Power. Evaporative Duty. lb. of water at 212deg. Fah. lb. of water at 60deg. Fah Phenol .12.2437 10-5025 Cressol .13-0096. Napthaline, 15:4635 Xylol ......16-5866. Cumol ......16.7838 Cymol ......16·9422. 11.1632 13.2675 14.2415 14.4126 14.5500 It is possible that dead oil may contain other substances richer in hydrogen than any of the above, and in that case the oil would have a proportionately greater evaporative power, but having regard only to these constituents of dead oil which are known, it will be seen that their evaporative power varies from 12-24 to 16.94, and that when burnt under the condition above mentioned, the evaporative duty of which they are capable varies from 10.5 to 14.5 per pound of each substance, the average evaporative duty being equal to 13023lb. of water, heated from 60deg. Fah. and converted into steam at 212deg. Fah. Consequently, the evaporative duty of dead oil will vary this amount according to the relative proportions of these substances which it may happen to contain. The result thus arrived at, on theoretical grounds, presents a very striking approximation to that obtained in the practical trial on board the "Retriever," on the 23rd inst., viz., 12.356lb. for the evaporative duty, which is only 667 less than the maximum duty indicated by calculation, if it be correct to regard the composition of dead oil as represented above this approximation, between theoretical and practical results, would indicate that the application of liquid fuel, according to only a very perfect combustion of the oil but also Messrs. Dorsett and Blythe's system, ensures not a very full utilization of the heat generated. The very small amount of smoke produced during the trial would involve some waste of heat, and would to some extent account for the difference between in the trial the average temperature of the furthe two results; but it must be remembered that nace gas discharged into the funnel was only 572deg. Fah., or 522deg. above that of the air supply, while in the calculated result it is taken as being 600deg. Fah, above the air supply; so that in the practical trial there was a more efficient and economical application of the heat generated than has been assumed in the calculation. A still further economy of the heat generated might be effected by heating the air supplied to the furnace by the waste heat passing away into the funnel and it is probable that in this way the combustion might be regulated and rendered so perfect that there would not be any waste of heat arising from smoke. These considerations lead to and justify the presumption that when the various appliances for burning liquid fuel according to this system shall to the conditions and requirements of steain navihave been more thoroughly perfected and adapted gation, an evaporative duty of 131b. per pound of oil burnt may be realized. But having regard only to the result actually obtained at present, it will be seen that the evaporative duty realized in this trial is about 100 per cent. greater than that ordinarily obtained with an equal weight of coal in steam vessels-that is to say, a duty of about 71b. per pound of coal consumed. Therefore, the weight of oil required to fuel a vessel would bo one fali of coal, or the weight of fuel to be carried would be only half as much as when coal is used. Then, taking the ton of coal as stowed on board a vessel to occupy 43 cubic feet, and the ton of oil as occupying 34 cubic feet, the quantity of oil equivalent to one ton of coal would occupy only 17 cubic feet, so that the saving in stowage space would amount 60-4 per cent. of the space required for coal. |
