respect being paraffine oil. After speaking of the tern or design being produced by bringing one on albo-carbon or by better burners and fittings? S. R. C. COMES OF RIGEL AND POLARIS. France. can be distilled without change. They have a pungent odour, and are fluid and oily at the ordinary temperatures. They have a bitter taste, and redden litmus paper. They occur in vegetables and animals; for instance, formic acid is found in red ants, and valeric acid in the valerian root. They can be likewise obtained by the decomposition or oxidisation of vegetable and animal substances. The fats or oils, when strongly heated in air, burn alone, or by inserting wicks. Palmatine and stearine fuse between 46° C. and 71° C. being found chiefly in solid fats, while oleine is fluid at 0°C., and is found principally in fluid fats. The fatty acids may be procured by the injection of steam super-heated to from 250 to 320 C. in heated fats. Heat is produced by the oxidation of drying oils. By heating the fats and oils with oxide of lead and caustic lime, their saponification is effected; but little glycerine is produced, as their is little water to react on the glycyl CH, when liberated from the fat. The fats are more fusible than the acids derived from them by saponification, but they harden more when exposed to low temperatures. The fats or oils are insoluble in water, soluble, to oils are mixed with an aqueous solution of the Saponification takes place slowly when fats or alkalies, but this action takes place immediately if the oil is dissolved in alcohol and mixed with an alcoholic solution of caustic potash at the boiling point. An emulsion is formed when fats are shaken with an aqueous solution of gum, albumen, and other substances that increase the density of the water and render it viscid, the whole assuming a milky appearance from the suspension of globules of oil. PRESERVING EGGS. [15384.]-I HAVE frequently seen inquiries in your paper as to methods of preserving eggs, and I send you a description of a process which Mr. R. Gerstl, thought it worth while to patent. It is nothing a greater or less extent, in alcohol, and easily describing himself as a "scientific chemist," more than dipping the eggs in lime-water and ex-soluble in ether, oil of turpentine, and benzol. posing them to carbonic acid, by which a carbonate They act as solvents for phoshorus, sulphur, &c. of lime is formed in the pores of the shells. I do not know whether this process is original with Mr. [15381.]-MR. WEBB in his valuable work "Celes- Gerstl, but I believe that eggs so treated require tial Objects for Com. Telescopes," gives the mag-puncturing with a good-sized. hole before boiling, nitudes of the companions of these two stars as or they will crack all over, and leave their contents 9 and 9-5 respectively. The most cursory examina- in the saucepan. At least several eggs having tion of these two objects will, however, at once served me that way, I asked the seller, and he show that the magnitude of the comes of the former said they must have been dipped in limewater, when compared with the latter is considerably which it seems is a not uncommon practice in underrated. Mr. Proctor gives the magnitude of Ovophile. the companion to Rigel as 7th mag.; from several observations I think this is nearer the truth than the magnitude given by Mr. Webb. The difference in the magnitude of the companions of these two stars is made the more striking when we take into consideration the respective positions of the primary and companion star in each case. Polaris has a considerable altitude, and is a 2nd magnitude star, the companion being 18-6" distant, whilst Rigel having a considerably lower altitude is a 1st magnitude star, the distance of the companion being only 9-5; yet notwithstanding its closeness to Rigel it is usually very conspicuous with any aperture above 3in. The companion to Aldebaran, when compared with that of Polaris, seems to me to hardly show the difference in magnitude, as one would be led to expect, seeing their magnitudes are rated as 12 and 9.5 respectively. January 30th. W. Goodacre. OILS FIXED AND ESSENTIAL. And these fats can be resolved by saponification The fats, or fixed oils, are of animal or vegetable the oils. Oils penetrate paper, rendering them transparent, and producing a greasy stain. Rancidity can be removed by shaking the oil in water containing magnesic hydrate. Glycerine is formed when saponification takes place. A plaster is formed by the combination of plumbic oxide with a fatty acid. Tartaric acid, or hydrochloric acid, separates the fatty acid from the oleate or stearate. Butter consists of about 87 per cent. of the fat of milk, 10 of water, 1 of caseine, 1 of common salt, and per cent. of sugar of milk. The milk fat in butter consists of a mixture of oleine, much palmatine, stearine, and several other fats-as caproin, caprylin, and butyrin. When heated in a glass tube, it melts, the water remains at the bottom, the curd on its surface, with a little of the melted fat, and the top layer consists of a fluid like oil. In animals, fat is found in the omentum, under the skin, and round the kidneys. The fat of warmON THE ASSUMED TEMPERATURES OF blooded animals is generally solid, while that of cold-blooded animals and fish is liquid. The principal solid fats are butter, grease, lard, and suet, and the fluid animal fats are cod-liver, neat's-yield foot, sperm, and whale oils. THE PLANETS. [15382.]-J. H. E." in the last par. of letter 15351 says, "It has not been satisfactorily explained why our world is not made a single degree hotter at any minute during its perihelion passage." In some elementary papers in the Day of Rest by Mr. R. A. Proctor ("The Earth as a Planet," p. 77, 1878), I find it stated that the earth does get more heat in the proportion "16 is greater than 15," and further on that "in Australia the cold of winter is made bitterer, and the warmth of summer more intense by the sun being nearer the earth in the summer, which is our winter, than in their winter, which is our summer." Is not that a very plain statement? Texan. : In vegetables, fat is found in the tissues of plants, and their seeds and fruits. Linseed contains 20 per cent., and rape seed twice that amount of fat. In animal and vegetable fats, a certain quantity of an albuminoid occurs that exerts an important chemical action on the fat when kept for any length of time. The fat is generally extracted by pressure from plants, and when the fat is solid at the ordinary temperature, it may be obtained by boiling the portion of the plant containing the fat with water, and allowing to cool, when the fat will form a solid layer on the top of the water. All fats and oils are lighter than water, the specific gravity varying between 91 and 94. When pure, and in the fresh state, they are without odour or taste, but on exposure to the air, they become oxidised and acid, acquiring rancidity, a disagreeable odour, and a deeper colour. Palm oil, cocoa-nut oil, and nutmeg butter are solid vegetable fats. The fluid vegetable fats, or oils, are divided into the drying and non-drying. The drying oils, when exposed to the air in thin layers, absorb oxygen, becoming dry and solid, which renders them useful in the preparation of oil colours and varnishes. The non-drying oils are converted into elaidine by mercurous oxide, and they do not absorb oxygen. LOOPED OR TERRY WEAVING. [15383.]-SEEING that several of your readers take an interest in weaving matters, I wish to call their attention to some improvements in Terry fabrics, which have been patented by McCabe, of Droylsden. The principal feature of novelty in the cloth produced is that the cloth has an even terry or looped effect all over the surface, and the pattern or design is produced by variations of colour only. To effect this object twice as many pile warp threads are employed as there are of ground threads; and the warp threads are drawn in (either two or more in a dent), in the following order :One ground, two pile, one ground, two pile, and so on, instead of one ground, one pile. A fabric of this kind may be produced by using the same number of pile warp threads as there are of ground warp threads, drawn alternately (that is, one and one); but this method does not produce so good a face as the employment of two pile threads to one For each ground warp thread. knock up there are three picks of weft-viz., one ground Castor-oil is partly a drying and a non-drying pick between two pattern or terry picks-oil, forming a link between these two classes. and the pattern cards in the jacquard or The true or solid acids occur only as constituents dobbie and arranged accordingly-that is, two of vegetable or animal fats. The acids, from lauric pattern picks exactly alike, between which is a to melissic, are solid at the ordinary temperatures. ground pick precisely the reverse. These three picks are "knocked up" together, drawing the pile or terry warp into loops. The draught is so arranged that all the pile threads across the piece form loops or terry at each "knock up," the pat Linseed, and some other drying oils, when mixed with tow or cotton wool, absorb oxygen so rapidly as to take fire. Linseed, poppy, walnut, hemp, and cod-liver oils are drying oils. And colza, olive, rape, and almond are some of the non-drying oils. They cannot be distilled without decomposition Oleic acid forms another group of the fatty acids. Butter dissolves in alcohol. When the fats in butter are saponified they each glycerine and butic, caprylic, caproic, and myristic acids. Grease is a general term applied to all fatty and oily substances having some solidity, as the various kinds of dripping, fat, kitchen-stuff, tallow, &c. It is used in the lubrication of the rolling-stock of railways, in the form of oil for the more delicate parts of the locomotive, and grease for the wheel axles. The grease for the wheel-axles is an inferior sort, containing a little tar, dirt, and other impurities, that render it unfit for candle-making, &c. Locomotive Grease is, strictly speaking, kind of soap, as there is a small quantity of soda used in its manufacture. It is made of animal fat, or the vegetable fats, palm-oil or cocoa-nut oil. The ingredients for summer and winter grease are mixed in different proportions. Grease for summer use consists of water, tallow, palm-oil, soda, and sperm-oil, in the proportion of three-fifths, two-ninths, one-eighth, one-nineteenth, and one-eightieth, respectively. And winter grease consists of the same materials, in the proportion of two-thirds, two-elevenths, one-eighth, one-eighteenth, and one sixty-sixth respectively. Wagon Grease is cheaper than locomotive, and is made of caustic lime and a resinous oil, but pitch oil, fish oil, cotton-seed oil, &c., may be used. Mare's grease consists of the fat of horses, imported chiefly from South America. It is a very oily fat and it is used for lubricating machinery. Bear's grease consists of purified veal fat, hog's lard, beef marrow, spermaceti, almond oil, and some scent. It is made up into pomades for the toilet. Real bear's grease is scarce. Lard is the melted fat of the pig. It contains stearine, oleine, and margarine, the oleine predominating. When pressed at a low temperature oleine and stearine are separated. The latter is used for making candles, and the former, under the name of lard oil, is used for lubricating machinery. Lard, when pure, is without taste or smell, and is white and firm. The best lard is obtained from the fat surrounding the kidneys. When melted it should be transparent and clear, like water, and when heated to 100° C. there should not be a trace of deposited matter nor the slightest ebullition. With lard H2SO, of specific gravity 1.64 gives a light brown colour, and nitric acid of specific gravity 1 gives a very slight yellow. Suet is the fat from the omentum and the kidneys of the ox and sheep. It consists of a mixture of animal fats, stearine predominating, forming about three-fourths of the whole. When suet is melted it forms tallow. It is white, soft, and almost odourless. It fuses about 40° C. Cocoa-nut Oil is obtained from the kernel of the cocoa nut. It has a disagreeable odour and a mild taste. It is used in the manufacture of stearine candles and marine soap. On saponification it yields caprylic, caproic, butic, myristic, palmitic, and lauric acids. It also contains oleic acid. The oil is obtained by pressure or boiling. In tropical countries it is liquid, but in colder countries it forms a solid butter-like whitish oil. It melts about 21° It dissolves in benzine, the fixed and volatile oils, and in ether and alcohol when heated. When treated for some time with nitric acid, succinic, suberic, adipic, anchoic, and pimelic acids, with nitrocaprylic and nitrocaproic acids, are formed. Palm-oil is obtained from the fruit by crushing it and boiling with water to separate from albumen. It is fluid in warm countries, but in cold it assumes the consistency of butter. It has the odour of violets, and is of a golden yellow colour. It is used for making candles and soap, and for lubricating machinery. It consists principally of a fat termed palmatin, which, when saponified with an alkali, yields palmitic acid. It soon becomes rancid, and its fusing point rises from 28° C. when fresh, to 38°C. when rancid. It is bleached when exposed to a high temperature, in contact with the air, or by oxidation with potassic dichromatic and H2SO,. Hugh Clements. (To be continued.) [33234.]-The Flute.-I am sorry I should have [34670.]-Geometrical.-Observing that you SNOW-RAISED BREAD AND PASTRY. Will others try the above experiment and report thereon? F. M. Crichton. Winding Engines for the Rhondda.-Messrs. John Fowler and Co., of Leeds, have just started the largest pair of winding engines ever put down in South Wales. The conical drums are more than 30ft, in diameter. This firm is just commencing the of some vertical engines for the new colliery Yard, which will be the largest winding gland, if not in the world. [34767.]-Electric Clock. I presume you want one clock every minute to send a current and move on a dial; if so, there is no electric contact that can be depended on; mercury will not do, because the spark soon chemically alters the moving contactpoint; a flat contact, either moving or steady, will not do, for dust will at times get in between; the best is a comb with fine springy teeth pressing on cam on escape-wheel; but the very day you have everything perfect the dial will lose time by the clock. Electricity, when used for bells, is the very emblem of constancy, but when used as above seems sometimes to sleep.-POND. [34803.]-Analysis of Cloth.-It does not matter whether you read the design from right to left or from left to right, if you turn it the proper way to take off the tramp. If you read off the [34861.] Call for Telephone (U.Q.)-If you intend to fix a bell to the line you will simply require a brass spring on a board with three studs for contact at each end of the line. Mark the left hand stud or No. 1 "Telephone:" the centre (No 2), "Line Bell," and the right-hand one (No. 3). "Bell." Keep the switch on No. 2; when you hear the bell turn the switch on to No. 3 to ring bell at other end, then turn it back on No. 1 and put your ear to the telephone.-C. CRAWFORD CORY. diameter, 6 feet stroke; the steam-cylinder is 32 [34882.]-Air Compressing Pump.-24-inch inch diameter, 6 feet stroke; 15 revolutions per minute; the steam in boiler 50lb. per square inch; the air in boiler 50lb. per square inch; on receiver. What I cannot understand is, how many cubic feet will this air-pump throw into the boiler per minute of 50lb. pressure per square inch? Will "W. P. T." please explain it for me? -A WORKING ENGINEER. [34976.] Tangent Testing. Thanks to J. W. E." and "French" for their letters on the above. The test required is an insulation test of an ordinary line of wire (overland). I have compared the calculations given by J. W. E." with the calculated resistances, which gives the answer to be 4704-7 Ohms through a constant of 45'. Following is the result of three days' testing, the Zm on each occasion being frosty : Since my last letter I find I am in error re the tangent of 45°. I should have said, "If the constant reading through 1,000 45', and then the earth rdg. being 45° 1,000"." I give my address in answer to J. W. E.'s" kind offer, and if he will state whether the above calculations are correct or not, I believe I need not trouble him further, except that J. W. E." says the wires, having been earthed; should it not be, "having been duly disconnected" as the instruments are cut out at each end; if not, a single needle-instrument offers an amount of resistance equal to ten miles of wire.-G. REED, 5, Bateman-street, Derby. [35199.]-Speculum Grinding. If "J. J. B." find several machines for grinding specula. I doubt can see the back volumes of this journal he would whether any one has tried fluoric acid, and I should not care to make the experiment.-J. T. L. [35209.]-Boiler Pressure. As my original reply to this question is mentioned in that of "Novus Homo," which has called forth the last reply of "Lancashire Fitter," I trust the latter gentleman will allow me to consider myself an interested reader, and as such, to write a few words on the subject. I would first notice that the rule for terminal pressure given by "Novus Homo" is the same, though, in my opinion, better worded, as that previously advanced by "Lancashire Fitter," with the exception of its unfortunate restriction to condensing engines. Before considering "Lancashire Fitter's" example from practice, allow meafow words on the fitness of the above-mentioned rule. It is an application of the law of Mariotte, which states that if a perfect gas expand at a constant temperature, the product of the pressure and volume at any instant is a constant quantity, i..., the pressure must vary inversely as the volume. If we take a base line and set along it as abscisse the volumes at different instants, and at right angles set up ordinates to represent the corresponding pressures, we may draw through the extremities of these ordinates a "curve of expansion." The form of this curve is the Hyperbola. Again, it is a fundamental law of Thermodynamics that when a gas expands heat disappears. From this it is evident that the hyperbolic curve requires the application of heat during expansion, and if the gas expand in a nor lose heat during expansion, the "curve of non-conducting cylinder, i.e., so as neither to gain be below the hyperbola. Scientific men have termed expansion"-with the same initial pressure-will this the "Adiabatic curve." expansion in a conducting cylinder, the position of of heat received or given out during expansion. I the curve of expansion will depend on the amount there be loss of heat this curve will be below the adiabatic curve; if a gain, above it, and above, or below, the hyperbolic curve, according as the heat received is more or less than that required to keep a constant temperature. The cylinders of steamengines being conductors of heat the last case is the one we have to consider. There are two ways in which the surfaces of cylinders affect the temperature of the steam, viz. :-(1) Radiation; (2) What is called "Exhaust Waste." The latter requires a word of "Now, in the case of explanation. While the cylinder is open to exhaust it endeavours to cool itself down to the temperature of the exhaust steam, consequently on admission of which will be again cooled during return stroke, steam, heat is absorbed in warming up the cylinder, the heat passing off through the exhaust port. Hence (2) always tends to lower the curve of expansion; (1) tends to either raise or lower it according as the cylinder is steam-jacketed or not; for in the former case heat is communicated to the steam in the cylinder, and in latter case withdrawn. It has, moreover, been found that jacketing cylinders reduces the exhaust waste by the tendency to retain the cylinders at the temperature of the steam in the jackets. Consequently the hyperbolic curve will only approximate to the case of jacketed cylinders. It will be evident that the effects of both (1) and (2) will depend on the proportion of surface to volume of cylinder. Now for a given volume of cylinder the surface is least when the diameter is equal the stroke, or if the piston surface be included, stroke 14 diameter. Turning now to the example given by Lancashire Fitter," I should imagine from the loss of pressure between boiler and cylinder, that either there was a considerable length of main steam pipe, or more likely that the engine was throttled. But whatever be the cause, it does not affect the point at issue, namely, the method of obtaining the terminal from the initial pressure. I should imagine the cylinder not jacketed, which would necessitate the curve falling not only below the hyperbolic curve but also below the adiabatic. This effect would be more marked from the stroke bearing such a large ratio to the diameter, viz., 2-18 to 1. Even this would, I should imagine, give a higher terminal pressure than that given. May I ask if there is not a drop near the end of the stroke due to the cylinder being open to exhaust? I have not written the above with any feeling of antagonism, but to endeavour to throw some light on the subject, and shall be glad to be corrected if in error.WYLIEL. [35203.]-Geneva Watch Cylinders.-"L. Sutair" will find full instructions relative to "turning-in cylinders to Geneva watch" in No.425 of the ENGLISH MECHANIC, May 16th, 1873. If he be unable to obtain a copy I shall be glad to re-write the subject immediately on seeing the query repeated.-SECONDS' PRACTICAL WATCHMAKER. Surely "New Sub" can trace course of steam him- and workings were of very unusual dimensions. I for [35236.]-Nickel Plating.-Directions [35244.]-Freezing Point of Water.-What about 350 men working in a shift, and the quantity it [35343.]-Swash-plate Turning.-In the description given in Le Manuel du Tourneur, of the inclined plates shown at page 478 of this journal, [35276.]-Tenacity of Ice.-I must have put appears that the projecting boss at the bottom this question in a hazy manner, as "Natas" has contained a screw thread by which the piece was misunderstood it to a certain extent; but as the attached to the left end of the mandrel, but if this Windermere, Bowness, and Warrington accidents apparatus were added to an English lathe with trashow that it is a question of considerable importance, versing mandrel of the usual construction, which I will put it in another form, viz., When a thaw has no male screw at its left end, but is bored and sets in does ice become affected throughout its tapped with a female screw to receive the bolt with entire mass, or does the the thaw simply affect the which the screw guides are attached, it would be a surface as it gradually melts it away? My own simpler plan to make the piece fit without shake on impression is that a piece of ice thawed down to to the mandrel, and secure with a bolt passing given dimensions in a warm atmosphere and tested through the lower plates into the mandrel. If this would bear the same cross strain as a piece cut to bolt were the ordinary one by which the screw the same dimensions and tested in a frosty atmo-guides are fastened, and the cap of the mandrel, sphere. (2nd) Irrespective of thaw, does the tena- when not employed for screw-cutting, it might be city of ice vary as the intensity of the frost increases necessary, from the thickness of the hexagonal head of the bolt, to make a recess for it the lower and diminishes?-CLYDE. part of the oblique plate, or a bolt might be made for it with a shallow head, to be sunk entirely in the face of the lower plate. If "Telescope Tele" will address me a line to "G. C. C., Army and Navy Club," I may be able to arrange with him that he shall see the Manuel, and get from it the information he requires.-G. C. C. [35309.]-Chemicals. In reading the article on Drills, page 414, I saw what was new to me, viz., that plunging the drill, red-hot, into mercury would make it of a diamond-like hardness. I tried it, and found I could drill old files and keep a good cutting edge on my drill. Perhaps you may find it useful in your case.-S. M. M. entitling him to take possession, and after five years' [35346.]-Smoky Chimney.-Will "F. W.S." kindly tell me a little about The Rumford FirePlace, or where I can find a description.-POND. [35313.]-Canada. If "E." refers to "Free Grant Lands" he wil find he will have to go north [35210.] Clocks Working Irregularly.-In of "latitude 45°," but there is plenty open for [35356.] Resonance.-I must disagree with all probability the irregular action of the escape-settlement thence to 46°. That in the province of "Fiddler" in his explanations on this point. He wheel of "drum" timepiece arises from the escape"Ontario" is all north of "Collingwood;" and wheel being "out of round" (not circular), so that (speaking generally) south of Lake Nipissing. it only renders it audible. This is quite a mistake. says a tube or surface does not reinforce a sound; the teeth miss " locking upon the cylinder when Besides this there is a great quantity in Manitoba The only way to render an inaudible sound audible, the shorter arcs of the balance are produced. Or and the Saskatchewan Colony. He had better in the proper meaning of the terms, is to increase the escape-wheel may be "out of flat," whereby write to the Canadian Government Emigration the under side of the cylinder-lip strikes the web of Agent, W. Dixon, Esq., 11, Adam-street, Adelphi, the power of the ear as by an ear-trumpet. The the wheel when the highest part of it should pass who will, no doubt, give him full information with the sound, the tube, by adding to the original resonant tube and the sounding-board do reinforce under the cylinder. To alter the first supposed a map, showing the land open for selection, &c. A vibrations reflected ones of the same length, and defect, make the wheel deeper in the cylinder. The friend of mine in Canada who has settled on a free the sounding-board by presenting a broader visecond one may be corrected by making the wheel grant tells the a selector goes and inspects the dis-brating surface, so that a larger portion of air is flat, to effect which instructions have been pre-trict he likes best, picks out a lot, goes at once to viously given in these pages. The fall of the the local land agent and gets a "location ticket," minute-hand is a defect general with such roughly-made timepieces, and arises from the shake of the hour-wheel teeth in the nut-pinion of the minute-wheel. The fall of hand referred to is produced towards the three o'clock figure when passing the twelve, thereby the timepiece becomes fast so much as it falls, but when ascending the circle after passing the six o'clock figure, the hand falls back the same quantity as it did forward; hence of no importance.-SECONDS' PRACTICAL WATCHMAKER. [35316.]- Turning. Both Glatton and E. [35212.]-Oil Painting. Will not an extra Juleff give "Balachall" the orthodox practice when quantity of driers answer the purpose? To use they recommend spring tools for smooth finishing Whiting would certainly be to make bad work.-cuts. But if "B." will make a plain, straight, stiff tool with cutting and clearance angle just the same, [35213.]-Oak Sawdust.-If cannot be used but no spring part at all, it will do the work as for smoking fish, might be employed in the manu- well, and from experience I believe its edge will facture of bois durci. No indication of locality last longer without resharpening, as well as being being given, cannot offer many suggestions. simpler to make. All spring in tools must be theoretically regarded as lost power, but it is essenshould be in a direction to relieve the cut. tial that the little spring a tool always will have [35377.]-Chamber Organ.-I can assure "Saalways used a spring tool for water cuts until I saw licional "I had not forgotten the Clarionet when I the above form in "The Modern Practice of Ame-made my remarks on chamber-organ reeds, as it is rican Engineers and Machinists." This title led only a solo stop, and unless the organ is large, and me to expect more than I found, for this was the also the room it is in, it is worse than useless. For only new thing I learnt from its pages.-A. E. a small chamber-organ without a reed, a pressure DANCASTER. of 14in. is sufficient, but with a reed, 24in. to 24in. is preferable.-J. D.-W. S. M. T. J. M. [35221.]-Flooring of Workshop.-Nothing better than asphalte under the circumstances.BUILDER. [35223.]-French Clocks.-I have known the defect which " Fagan" refers to occur in consequence of the dirty and thickened state of the oil applied to the pivots. Such clocks usually go three weeks without rewinding, and when the oil becomes glutinous, the power from the mainsprings is much reduced after two or three days' going, and at times insufficient to fully discharge the striking; though by the continued pressure from the mainspring upon the striking-train the blow or blows are struck off during the going of the "time" train; hence, the next time the striking is produced the "blows" do not correspond with the time indicated by the hands. Try what cleaning the clock will do.-SECONDS' PRACTICAL WATCH MAKER. [35226.]-Beam-Pumping Engine.-For lack of particulars can only make a guess. The three valves at top would be to admit steam to upper side of piston, to transfer the partly exhausted steam to underside of piston, and to exhaust into condenser. 499 a customer of ours refers to our cement, and you I [35328.]-Mining Question.-I cannot permit the letters of "Marine Artilleryman 99 to pass without saying a word or two. In the first question, he recommends keeping a țin. drill a good 18in. in advance of the working face; and, further on, says, and, by increasing their length, they will meet "these simple instruments require no drawings, if there were any ordinary accumulation of water, cases like "A. B. C." mentioned. I am afraid, that before the hole tapped it the face of the drift would burst away, not being able to withstand the pressure, and the probable result would be the inundation of the pit. Besides, to do as advised by "M. A." would be to break the Coal Mines Regulation Act. (2.) "M. A." thinks that no ordinary furnace could ventilate a pit 60fms. deep, with 100 men working daily, unless the diameter of the shaft set in motion, and thus a sound of greater intensity resonance nor of rendering a sound audible, but of is produced. The telephonic fly is a case, not of conversion of vibrations. We do not hear the fly walk; we only hear the sound made by making and breaking the current in magnified imitation of sound is converted into an interrupted current, and the fly's walking. Or we may say the minute this is again converted by the receiver into a sound similar to but louder than the first. I would refer "Zeta" to page 201, Vol. XXVIII., where I have given a few illustrations of the action of soundboards which I think will help him. A resonant tube must be a quarter of the wave-length of the sound, so that the wave has time to go to the bottom of the tube and back to overtake the next wave in the same phase, and help it on its way, i.e., reinforce it has only to be made double the length of the it. "Fiddler" is wrong, too, about the open tube; closed one to respond to the same note; a node is then formed at the centre which acts like the bottom of the short tube.-WM. FIELD. allow me to supplement the answer by Mr. Wenham, [35383.]-Immersion Prism.-Perhaps you will by stating the way in which I use the hemispherical lens referred to by him. When it is put on the every movement of the slide takes it out of the cenunderside of the glass slip, as he suggests, with oil, observation of any particular valve very troubletre of the object-glass, and of course renders the some, and indeed almost impossible. To render the lens stationary, I hit upon an excellent plan, which so far as I know does not appear to have struck any one before, not even Mr. Wenham. I take the steel pin out of my parabola and replace it by another with a flat top, to which I attach the flat portion of the hemispherical side of the small truncated lens. The lens when pushed up on the top of the pin into contact with the slide is thus stationary, and any diatom on the slide may with the utmost care be brought under the illumination. In this way the illumination may be made quite equal to the effects of the Reflex Illuminator, when the under surface of the parabola is shut from to by paper diaphragms. The lens is very troublesome to use in any other way, but by this means it becomes extremely simple and easy in manipulation. I have often thought of suggesting this to Mr. Wenham, and that his firm should adapt their parabolas for use in this way; but perhaps he will now take the hint and adopt it.-W. FORGAN. As 100 74-87: 320: 239-584 real extract per which reduced to Saccharometer lbs. 2-77 | 239-584 white ash remains, cool and weigh.-HENEY P. HARRIS, 136, Peckham Park Road, S.E. [35418.]-Trade Unions.-"The Conflicts of Labour and Capital," by George Howell, will answer "P. C.'s" requirements. All other books I know of on this subject are inaccurate, insuffi cient, or not up to date. George Howell writes from the labour point of view.-T. A. T. [35419.] Bursting of Guns.-(1) When a powder explodes very rapidly in the empty space, space exists between the powder and the shot, the and the gases attain a dangerously high pressure before the shot can be put in motion, for it requires time for a pressure, however great, to put in motion a resistance however small. Hence the pressure wave impinging on the shot returns, meeting a a similar reaction from the rear end of the bore, and throws a sudden strain on the barrel. (2) In the case of an obstruction between the shot and muzzle, we have the shot travelling at a high velocity suddenly resisted, thus throwing a strain see articles in Engineering, January 10th and on the barrel. For a more detailed explanation, 17th.-WYLIEL. Determination of wort constituents.-Maltose.The only reliable method of estimating sugars is the gravimetric, and although it may require rather more time and trouble than the titration method, yet the result is far more satisfactory. Before commencing the analysis it is necessary to treat beers that have been fermented with subacetate of lead to remove nitrogenous bodies before using Fehling's copper solution, but this is not necessary with [35419.]-Bursting of Guns.-This question worts previous to fermentation. The method "T. A. R." puts under two headings; but they are recommended by O'Sullivan I consider most conboth due to exactly the same cause, for it is very venient. It is as follows. Construct a water-bath evident that if a slight obstruction in the muzzle of with two beakers. Into the inner beaker, which the gun be sufficient to cause a rupture in the barrel, should hold about four ounces, put 50cc. pure the same would be sure to happen if there were a water, and heat over Bunsen flame till the con- space between the powder and the projectile. The tents of both beakers boil. In the mean while the cause of the above is generally accepted to be this: wort extracted in the previous operation should be the gases which are generated by the burning of the carefully neutralised with soda, and 5cc. accu-powder produce a tremendous pressure behind the obstruction, and before they have time to impart sufficient velocity to it, to clear it from the muzzle, inconsiderable, offers an infinite resistance to the they have made their escape by bursting open the breech of the gun. A finite mass, no matter how instantaneous generation of an infinite velocity. pressure required on valve to raise lever.-H. C. B. EDGAR MATTHEWS. [35417.]-Analysis of Malt.-In the practical analysis of malt for brewers' purposes, it is necessary-1st. To determine the percentage of extract obtainable at an ordinary mashing temperature, and the general composition of the extract so obtained. 2nd. To determine the percentage of soluble and insoluble albuminous bodies in the malt, and then the percentage of moisture, acidity, and mineral ash. If in conclusion we submit a sample of the malt to microscopical examination it will be of service in enabling us to confirm the results of our chemical analysis. Insoluble matter or draff-Weigh up carefully 50 grammes (1-7637 ounces) of the malt, crush or grind it in a small coffee-mill, reweigh the ground malt, so as to be sure of employing exactly 50 grammes, and introduce it without loss into a beaker containing 300cc. water at 160° F. (71° C.), stirring constantly, the beaker must stand in a water bath, over the Bunsen flame, and the temperature should be kept at 150° F. (66° C.), for one hour, a gentle stir being given occasionally. The mash should then be tested with iodine to prove the conversion of the starchy matter, and then the temperature of the mash should be raised to 160 F. (71°C.), and kept at that temperature for one hour. The mash is then thrown on a muslin filter and rapidly washed with hot water at 170° F. (77°C.), until a filtrate of exactly one litre is obtained. It will then be a 5 per cent. solution. The draff is then removed from filter, placed in the air-bath, heated to 110° C. (230° F.), for two and a half hours, cooled, and weighed. The weight multiplied by 2 will give percentage of draff. According to Mulder the average in normal malt is 26.5 per cent. Dextrin. Boil 100cc. of the original malt ex- Albuminoid bodies are estimated as follows: VIRGIL. account of " [35421.1-Disease in Bullfinch.-This is usually caused by a small insect, colour red, varying to brown. Cover cage with piece of white muslin killing all found; after a few days, wash cage well, during the nights, and examine well in morning, and when dry, rub perches with linseed oil. I have lost several birds before discovering the cause. Hemp seed will also cause the same; very small quantities should be given, if any. I should like to hear how you succeed. A few of these insects alive would be very acceptable for microscopic purposes to me.-W. H. CHEESMAN. [35422.]--Defect in Viola.-What you term a defect in a viola is really not so. The want of exact harmony in such cases arises from imperfections in the strings; and such imperfections may be caused by the diameter of the string not being uniform throughout its length; or even a difference of density in the substance of which it is made, would cause discords when played according to exact Total albuminous matters are determined by sub- principles. The quality of a string may be tested mitting two grammes of the malt to the combus-in the following delicate way:-Stretch the string tion process. To estimate the amount of soluble and set it vibrating by means of a twang with the across two bridges (not under too great a tension) albuminoids, we evaporate 100cc. of the original finger, or otherwise; now observe if the loop extract over mercury contained in a dish placed formed by the vibrating string is symmetrical at all over a low flame, until a dry crisp cake of the extract is left. This cake must then be powdered above-mentioned causes.-E. K. DIXON. points, if not, the string is bad, arising from the and mixed with soda-lime, and a nitrogen combustion made with it. The result deducted from the total nitrogenous matter found in the dry malt will give amount of insoluble albuminoids. excise ammonia. per 66 66 [35422.]-Defect in Viola.-"H. C. K." attributes "Viola's" difficulties to his incorrect fingering only; may I suggest that the fault does lie (pace "H. C. K.") at least as much in the strings themselves? What "H. C. K." says about the strings is perfectly true, provided they really are what they should be-namely, each one perfectly uniform in size and density throughout its length. Now most fiddlers will agree with me in saying that unfor tunately it is extremely difficult to get a set of strings which fulfil these conditions accurately, and instrument is well in tune, so that the fifths given are really true among each other. The test of a true" set of strings is simply this, that when the by each consecutive pair of open strings are perfect (a mere matter of turning the pegs), then equal lengths of contiguous strings stopped on any part of the fingerboard must also give perfect fifths. I think I may safely say that it will hardly happen once in twenty times that a set of grammes of the crushed malt and drying at 110 C., strings taken at random will answer this test then weigh. Good malt should not contain over quite truly. The D and G strings (as "Viola" 4 per cent. moisture, and malt straight off the kiln finds) are especially troublesome in this respect, should not have more than 3 per cent. moisture; and it is common enough to find a pair which give after storing it should not have more than 45 per a minor sixth instead of a fifth when they are cent., and any over that amount will cause putre- stopped at equal lengths near the middle of the factive fermentation. fingerboard. Violin strings are by no means Ash.-Weigh 2 grammes of malt in a tared pla-exempt from this fault, although they are perhar tinum crucible, and ignite until nothing but a fine easier to match than tenor strings. The comfort of Estimation of Acidity. This may be considered as consisting of lactic acid. Digest 50 grammes of ground malt in 100cc. of cold water for five minutes and stir. Strain through muslin in a funnel over a 100cc. measure, and when about one-third the bulk of liquid employed has filtered through into the measure, estimate the acidity with standard Extract and produce per quarter.-The specific Example-As cc. taken : 100 gravity of the filtrate obtained above must be very adding more to the above, and dividing by 5, :: ammonia used: per cent. acetic acid, then by accurately taken by means of balance and bottle. Then to calculate the solid extract per cent. deduct gives per cent. of lactic acid. From 0-2 to 0-3 1,000, and divide the remainder by 3.85. To find cent. lactic acid should only be allowed, and 0.4 pounds per barrel, deduct 1,000, and divide the per cent. is unusual, and denotes unsoundness. remainder by 2-77. And by multiplying the weight A good malt should not neutralise more than 0-1 over 1,000 by 2-77 we find the real weight of to 0-15 per cent. anhydrous sodium carbonate. extract in the filtrate from 1 litre wort, or 50 Moisture. This is determined by taking 2 grammes of malt, which multiplied by 2 gives the percentage of extract obtained under the same circumstances of heat and time as the malt would have been when brewed. The percentage of extract is converted into extract per quarter by a very simple sum, the data required being the weight of the malt employed. Then if we have an extract per cent. 74.87; malt weight, 40lb. per bushel, or 320lb. per quarter. |