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291 and revolving rod as before described, I ain aware that I have been much and for the purposes aforesaid, and with censured for presuming to question the 1 cover or cap to place over the lime as engineering skill of those who are conaforesaid."

nected with boiler-making. When, however, we find those engaged in this im

portant department so misled, the want ON THE MANAGEMENT OF FURNACES AND of some more practical details will not,

BOILERS. BY C. W. WILLIAMS, ESQ. I trust, be disputed ; and I may here ob

Sir,- In my last, I enumerated the serve, that I have already had abundant several kinds of combustible gases which proof from many of the highest standing are produced in a furnace, and for which in this branch of business, that I have a supply of atmospheric air will be re not laboured in vain. quired. The following tabular view of I have already characterized the gases their relative quantities, as generated

evolved in a furnace, by the general terms from each charge of coal, with the pe

of coal gas and coke gas, (see Mech. riods of their respective development and Mag. No. 961,) as well for the sake of length of fame during the varying stages brevity, as of directing attention to the of the process, will convey a fair practical peculiar

nature of the difference between estimate of the effects produced in a well the former, as generated from the coal, regulated furnace by the admission of during the early part of the process, and fresh supplies of air--in the right place,

the latter kind of gas, as produced, durand the right manner. These results ing the later stages, from the clear red, (and which may be tested by all, without or glowing embers on the bars, as they the aid of a laboratory or chemical pro progressively approach to the character fessor) cannot fail to convince us how we or appearance of a coke fire. As there have been led astray on this subject, by are many important considerations arising the oversight of practical as well as theo

out of these two states of the charge of retic men; among whom may be men

coal, which are intimately connected with tioned Tredgold and his followers. Not

the admission and action of the air, it is possessing, or adopting, the means of of the last importance that we keep this internal inspection, such men, notwith

distinction in mind-many of the pracstanding their unquestionable talent and

tical and chemical errors of

“ smoke scientific acquirements, have, themselves, burning" inventors being clearly tracebeen led to form very erroneous notions

able to its neglect. I will here, then, on the power and length of flame, and briefly observe, that, by coal gas, is the admission of air to furnaces—giving

meant the hydro-carbon gases (com. precise rules for the proportions of fur posed of carbon and hydrogen) evolved naces and boilers, with even the appear

from the coal, before it assumes a red or ance of mathematical precision. ** The ignited appearance; whereas, by coke distance," says Tredgold, “to which the gas, is meant the carbonic oxide, (comfame and heated smoke of a fire will posed of carbon and oxygen,) formed extend, so as to be effectual, will depend

from the carbonic acid, in its passage op the draught of the chimney and the through the glowing ignited mass on the nature of the fuel; from three to six bars, in the form of coke, and after the feet will be about the range in a well

coal gas has been expelled. The quanconstructed fire-place : that is, about six tity of this coke gas will then be in profeet with coal and a good draught, and portion to the thickness or body of such about three feet with coke and slow ignited mass—the current of air passing draught. This, of course, will regulate through it, in its state of incandescence. the length of the boiler.''

What con

Carbonic oxide," observes Professor nexion those six feet, or three feet, have Graham, (in common with all the other with the length of the boiler, it would be authorities,)“ may be obtained by transvery difficult to define on any rational or mitting carbonic acid over red hot fragscientific grounds; and I am prepared to

ments of charcoal contained in an iron or showthat the dictum of Tredgold (which porcelain tube. The combustion is often has recently been republished under high witnessed in a coke or charcoal fire. The sanction) is unsound and wholly unwar.

carbonic acid, produced on the lower rapted in every particular.

part of the fire, is converted into car


bonic oxide as it passes up through the bustible gases evolved and entering into red hot embers." I here make this combustion, (if supplied with air,) as far special reference to the process by which as can be estimated by the length of the this carbonic oxide (which I call coke flame passing from the furnaces over the gas) is produced, as I perceive some bridge, and into the flues. It is possible practical men err by considering it to be the generation of the coke gas may, to a an original formation arising out of the certain extent, continue longer than the glowing matter, after it has been reduced fir five minutes, and begin sooner than in temperature; whereas the fact is the at the end of thirty five minutes, as erreverse, as practice, and the highest au pressed in the table—the brilliant light thorities, prove: namely, that carbonic from the coal gas preventing the feebler acid, being first generated, takes up, light from the fame of the coke gas from

it passes up through the red-hot being perceived. These, however, are embers, an additional portiou of carbon, minor and insignificant details. I have aided by the intense heat of the incan aimed solely at giving a general description descent mass: the incombustible carbonic of what is seen; in all cases, however, the acid being thus converted into combusti- quantity and length of the flame are unble carbonic oxide.

derrated, rather than overrated. The To this latter, air must therefore state of the fire at the time of the charge, be admitted, by some other quarter and many other circumstances, tend to than through such fuel itself from the alter the quantities and times: the above, ash-pit; since, instead of effecting its however, may be considered as a correct combustion, such air, so admitted, would general view of the matter. only increase its quantity, (by increasing By the table, it will be seen, that the the quantity of carbonic acid,) and make fame, which, according to the dicton of the evil worse.

Having detailed this Tredgold, would be but six feet, actually process more at length in my Treatise on reaches to a length of twenty-two feet, Combustion, I need not here dwell on it. (and even that is by no means the maxi

We will now further consider our mum,) while its minimum not less charge of coal on the furnace, and the than ten feet. Tredgold speaks also of following table will present a view of the the “flame and heated smoke," yet, in relative quantities of those two gases pro my furnace, from which the above table duced from it during the progress of its was drawn, and where the largest quancombustion.

tity of gas was produced, there was no Time in

Coke Total, and smoke whatever, not even as much as length of

would dull the bulb of the thermometer,

the flame being of a clear and brilliant Charge of coal

10 10

white colour. 5 minutes 10


Another writer on boilers (adopting 10 14

Tredgold's views) observes,

“ With 15 18

18 20

boilers whose fire grates are square, and 22

22 25 22

whose lengths are not less than four 30 18

18 times that of the grate, we have never 35 14

14 met with an instance of the flame reach. 10

ing to the end of the boiler, provided 45

13 there was a good draught and the fire 50

12 12 properly managed.” Now the boiler 55

10 10 from which the above table was taken, 60

10 10 falls in with these proportions, being Column 1. gives the time, in periods fifteen feet long, and the fire-grate of five minutes, when the observations square (three feet). Yet the flame not were made. Column 2. represents, in only reached the end of the boiler, but numbers, the estimated quantity of coal passed above ten to twelve feet beyond it gas evolved at such periods. Column 3. -often extending along one of the side that of the coke gas at the same periods. Alues, and even illuminating the second And column 4., being the sum of the In a score of other boilers, to which I two preceding columns, may be taken as have introduced the air in the proper indicating the gross quantities of com manner, the flame may be seen, during a













5 none

none none


293 large portion of an hour's charge, reach- being evenly spread, the appearance ining from twenty to thirty feet in length, side will present many interesting and und not an “imperfectly developed and instructive proofs and illustrations, which dall reddish flame,” but of a brilliant we cannot now stop to describe. and well-developed character.

Towards the close of the charge, and These are the errors to which engi- when the fame from the coke gas has neers are exposed, and by which ma sensibly diminished, it will be perceived bufacturers are led astray, from the that the time has arrived for a new charge, want of adequate means of observing and this without opening the fire-door to what passes within the furnace and Aues ; look in. If the proper time be suffered and the supplying the necessary air in to pass, or, should the next charge be the right place and manner. For, in the thrown on too soon, in either case the cases above named, when the air-admis- efficiency of the process will be materially sion orifice is closed, the flame is not affected—the appearance in the interior only shortened, but nearly extinguished will vary—the quantity, rate of progres-its length is reduced to the Tredgold sion, and even the nature of the evolved standard -and instead of the interior at gases will, in a great degree, be altered, mosphere of the flues being clear and and the question of time and economy transparent, it becomes dark, with a considerably influenced. There is no cloud of black smoke, which renders in difficulty in understanding all this. The ternal inspection impracticable, and sight- observer cannot be deceived by the misholes of no avail.

representations of interested parties, or By the above table, we see that before the truth obscured by plausible theories. the charge was thrown on the furnace, By such means of observation, the owner the coal gas had ceased to be produced : soon becomes his own master, and his the fire being then clear and of a glowing eyes are opened to the truth or fallacy of red, and the fame necessarily confined what he is called on to believe or practise. to that of the carbonic oxide, or coke This is, in fact, making the chemistry of gas. Of this there could be no doubt, combustion on the large scale, an easy, from its peculiar colour and character, as intelligible, and practical science. well as from the appearance of the ignited It is now to be observed, that during mass on the bars. On the charge, how the process of the entire charge, the aterer, being thrown on, the coal gas, we mosphere, as it were, of the flues, will be see, takes its place; the former ceasing perfectly transparent. This all-important to be evolved, or nearly so.

This is fact is at once ascertained by looking easily accounted for, when we consider through them, as from $1 to $ 2;-(see the great cooling effect of the fresh coals engraving in No.971 ;) should any cloudon the ignited mass, and which thus iness appear, or the flame assume a reddestroys the very cause of the production dish or murky colour, we are at once of such coke gas, namely, the high tem warned that something is wrong, and perature and state of incandescence. called upon to rectify it. This subject,

The coal gas then goes on increasing however, will be considered more in dein quantity and length of flame, until, at tail as we proceed. the end of twenty minutes, we see it has Thus, we perceive, that at no stage of reached its maximum of 22 feet from the the process, from the beginning to the bridge. Continuing in this state for some end of a charge, is there a flame of less time it gradually decreases, "while that than 10 feet from the bridge, and even from the coke gas simultaneously in extending to above 20 feet in lengthcreases, until the former has entirely thus at once negativing Tredgold's hyceased, and the latter alone prevails. pothesis. This fame being perceived to This progression, and even the existence be in immediate contact with the boiler of the two flames at the same moment, bottom, against which it impinges; where is quite perceptible, until the entire of then, it may be asked, can we find any the solid fuel on the bars has become ground for asserting that the length of clear with a glowing appearance. Should the flame should “regulate the length of there be any irregularity in expelling the the boiler ?" But with still greater force coal gas, as for instance, from the pre do I ask, where is the foundation for the sence of larger lumps, or the coal not assertion that there is no combustible gas

produced, and therefore, no demand for only begun to be understood within a air, when the fire in the furnace has be few years, and is even now much better come clear, red, or incandescent ? Or, known, and more scientifically acted on, that the air so introduced could have, not in certain parts of the Continent than a heating, but so cooling an effect, as with ourselves. actually to affect the boiler plates in Until ammonia was known to be the juriously? Nothing can be farther from really important matter of all manure, the fact. Such assertions could only be this, its very essence, was every where the result of mere conjecture, in the ab permitted to be volatilized in the process sence of internal inspection, since, with of violent fermentation, and is even still such aid, it would be impossible to deny so in most parts of our own country. A or resist the evidence of our senses : yet, better system, prevails, however, over a such theoretical absurdities are still palm. large portion of Germany, in Alsace, and ed on the unsuspecting manufacturer, in Holland and Switzerland. In the and even by those who affect to be prac latter country they wash the dung by retical men. Let such assertors bring peated watering at intervals. The wash. their theoretic reveries to the test of ob ings are collected, rich in ammoniacal servation. Let them examine a furnace salts, and are saturated with a solution of thus furnished with the means of inter- sulphate of iron, (green copperas) nal observation, and they will then be in with sulphuric acid direct, to change the a position to appreciate, by both seeing volatile salts of ammonia into fixed suland feeling, what are the results from phates, and in this state the liquid madure the admission or exclusion of air. The is applied to the soil. It produces the value of the admitted air, in effecting the most vigorous vegetation, and the sul. combustion of the evolved gases will, phate of ammonia being fixed, is all ashowever, be more fully illustrated when similated by the plants, in place of being we come to consider the actual tempera volatilized in the state of carbonate of ture and actual condition of the flues, ammonia, as with us, when crude ferwhich shall be the subject of my next menting manure is lavishly spread over communication.

our lands. Gypsum is often used in I am, Sir, yours, &c.

place of sulphate of iron, and is readily Ć. W. WILLIAMS. decomposed by organic matter in certain Liverpool, April 8, 1842.

stages of decay.

In Great Britian, where sulphate of

iron from refuse pyritose coal and gypPROGRESS OF FOREIGN SCIENCE.

sum may be had almost for nothing, it [In continuation from page 231.)

is singular to find its use thus almost un. Artificial Pouzzolanas.

known amongst us, while practised by Vicat, whose masterly, researches upon those to whom both these articles are the subject of limes and cements are so scarce and dear. well known, found, many years ago, that A M. Schattenmann, of Bouxmiller, in a slight roasting had important effects in Alsace, has greatly distinguished himself improving the clays used in the fabrica. in this branch of agriculture. As direction of certain pouzzolanas. He has

tor of some great chemical works, and lately announced, that in order that this having had under his disposal the manure roasting shall produce its maximum ef

produced by two hundred artillery horses, fect, it must be competent to expel fully cantoned for four years at Bauxmiller, he the water which makes the clay a hydrous has had opportunities of practically expesilicate of alumina.

rimenting upon a great scale, and has comBerthier has recently confirmed this municated his methods and their results to determination with reference to some M M. Dumas and Peligo. His dungcement clays, brought from Algiers; heaps are made on a great square space, the fact is of great importance in the paved or puddled, and with a fall from correct practice of making artificial all sides inwards. The stable dang is cements.

heaped all over to the height of about Foreign Agriculture.

12 feet; a well, sunk at one side, supplies a The true nature of manures, and the large quantity of water, which is at interrationale of their action on vegetation, has vals distributed by wood shoots over the

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heap, which is never permitted to get found to be eight hours after high water into a state of violent or heated ferment, at Dunkerque and Calais, so that it would ation ; the mass is stratified with pow appear that it takes that time to transmit dered gypsum, or copperas, and the the pressure of the tidal column from drainage from it, with all the washings, these ports, or from the nearest point of are collected in a large underground tank

coast, to Lille. in the centre, where they are saturated Some connexion between the tides and further, if requisite, with gypsum, or sul the level of well waters has long been phate of iron. This latter Auid is used, conceived, or observed, in various parts as requisite, by watering the surface with of Great Britain, but heretofore never it, and such are its potent effects, that he identified with the actual periods of rise says, a name traced out by watering with it and fall. Some extremely curious quesin the grass, can be distinctly traced in a tions of a geological character arise from few weeks by the dark coloured and vigo this result. How does the tidal water rous vegetation produced where it was act on that of the well, without gradually touched. The effects of this treatment making it brackish? Is the fresh water on the stable dung, are to produce, in merely contained between beds of clay, about three months, a mass (aussi gras or rock, which partly float upon it, and et påteux) as fat an? pasty as cow-dung, are compressed by the advancing lide, and, according to his experience, fully and forced to yield up their watery store, as powerful

like wine pressed from a skin; or do the For a journal not professedly agricul columns of salt and fresh water actually tural, the full details of this intelligent mingle? And if so, does the sea water gentleman's methods would be out of lose its salt in the bed through which it place; but to those interested in the passes, by decomposition, and become perusal of the original paper (“Comptes fresh? It is quite conceivable that such Rendu,” No 7, for February last) would re-actions might take place as resulting be important. The theoretic grounds on in nearly insoluble salts, would leave which this successful practice depends, the sea water as fresh as many spring have been fully developed in a form ac waters are found. cessible to the English reader by Dr. Metalliferous Deposits of Sicily. Leibig, in his report on organic chemistry, applied to agriculture, &c., addressed

An able report has been made to the to the British Association.

Academy of Sciences on this subject, by

M. Adrien Paillette. From this it apEffects of side upon Artesian Wells.

pears, that some time ago an English An Artesian well, which has been some company obtained from the Neapolitan time sunk at the military hospital of Lisle, government, authority to work mines in has been observed to vary considerably in Sicily, and full of expectation from the the force and volume of its supply. M boasted historical accounts of its ancient Bailly, captain of engineers, has made a riches, both mineral and agricultural, loog continued series of accurate obser. had, without any previous research, but vations upon the variation, and has ar merely on inspection of some old work. rived at the following conclusions. ing, prepared means of opening mines,

The maximum supply is=63:55 lit. and working them on a large scale. The per min. The minimum = 33 lit. The results were unsuccessful, like many mean of all the experiments 48:55 lit. others of the same sort, begun in the

The maximum height to which the same reckless way, on both sides of the water will rise (above the surface namely) Atlantic; and they were now so discouwhen prevented from flowing off is raged, that the pumping engines, and 2-385 metres, the minimum 1.956 metres, stampers, &c., brought at an immense the mean of all 2.253 metres.

cost from Wales, lie to this day in store The greatest variations, both in supply at Messina, or abandoned on the shore. and height of column, correspond with Under these circumstances, some of the the periods of the moon's syzygies, and principal parties concerned determined to the minima of both correspond in an send a commission of mining engineers equally constant manner with the time of

to lea

what were the real mineral riches quadratures. It may hence be concluded of the country. M. Juncker, ingeniéur en that the phenomena are due to the tides. chef of the Royal School of mines, and The periods of maximum supply were M. Paillette, civil engineer, were ap

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