} 4 (0^ MECHANICAL fXDUSTIlIES EXPLAINED MECHAOTCAL INDUSTMES EXPLAINED SHOWmG HOW MAMl USEFUL ARTS ARE PRACTISED WITH ILLUSTRATIONS BY ALEX AN DEI! WATT AUTHOR or "sciKNTiFic inhttstries," " klectro-metallurgy," etc. etc. CARVING IRISH BOG-OAK. ETCHING. GALVANIZED IRON. CUTLERY. GOLD-BEATING. BOOKBINDING. LITHOGRAPHY. JC:WELLERY. CRAYONS. BALLOONS. nep:dles. lapidary. ironfounding. pottery and porcelain. typefounding. j BREAD-MAKING, i BRONZE-CASTING. 1 FILE-MAKING. OR MOULU. I PAPIER-MACH^:. ETC. etc;, etc. W. cl' A K. JOHNSTON EDINBURGH AND LONDON 1881 P E E F A C E. Apart from our ordinary studies or pursuits, it is undoubtedly an advantage to have some "hobby," or means of recreation, other than those which are too frequently adopted for the mere purpose of " killing time." While there are some whose mental inclination leads them in the direction of philosophic science or literature for their recreative pursuits, there are many whose taste leans towards those of a more mechanical nature. In all grades of society, from the highest to the more humble members of the community, the vast field of mechanical art has been explored for the purposes of intellectual enjoyment. Moreover, the pleasure to be derived from making or constructing mechanical objects is not only a most agree- able pastime, but the work, if creditably executed, remains as a testimonial to individual labour and skill, and the simple title Hand-made carries with it a history of patience, perseverance, and industry which should entitle it to a high rank in human estimation. Those who may have no desire for a more intimate acquaintance with mechanical operations than may be gleaned by reading, will, it is hoped, find in these pages sufficient information concerning some of our important mechanical arts to interest them, while, at the same time, it has been the author's aim to render the work acceptable to the rising youth of both sexes as a source of useful information and instruction. CONTENTS. PAGE Annealiug Glass ....... 22 Balloons 44 Blacklead Pencils ....... 137 Bookbindini; ....... 63 Brass, Manufacture of ...... 89 Bread-making ....... 46 Brick-making ....... 95 Bronze ........ 108 Bronze-casting ....... 18 Burnisliing ........ 163 Button-making ....... 148 Camel-Lair l*encils . . . . . . .115 Carving Irish Bog-Oak ...... 1 Case-hardening ....... 17 Cask-making ....... 102 Cotton Wadding ....... 88 Crayons ........ 40 Cutlery ........ 34 Eniery-wlieels ....... 98 Etching 124 Etching on Glass ...... 27 File-making . . . . . . .105 French Polishing . . . . , , .122 Fullers' Earth ....... 103 Galvanized Iron ....... 51 Gilding with Gold-leaf ...... 55 Glass-cutting . . . . . , .176 Gold-heating ....... 52 Gold Bronze . . . . , . . 1()2 Ironfounding . , . , . . .112 viii CONTENTS. PAGE Jewellery ........ 182 Lead Shot, Manufacture of . . . . . .29 Leather-currying . . . . , . .178 Lightning-conductors . , , , , .62 Lithography . . . . . . .130 Making Small Tools ...... 158 Marble Cutting and Polishing . . . . .136 Matches ........ 171 Mercurial Gilding ....... 58 Metal Polishing ....... 150 Metal-spinning ....... 32 Moiree Metallique ....... 43 Mortars and Cements ...... 24 Needles, Manufacture of . . ' . . . .144 Or Moulu ........ 57 Papier-rnache . . . • . ' . .50 Playing Cards . . . . . .11] Potter}^ and Porcelain, Manufacture of . . . .64 Prince Kupert's Drops ...... 27 Pruning Trees and Shrubs ...... 82 Rotten-stone (Tripoli) . . . . . .129 Rustic Flower-vases ...... 77 Soldering ........ 92 The Art of Lapidary . . . . . .118 Tin-Plate, Manufacture of . . . . . .42 Type-founding . . . . . . .142 Wall-papers . . . . . . . . 168 Waterproof Cloth . . ^ 81 Whitewashing . . . . . . .117 Wire-drawing ....... 140 Index • . . . . . . . 193 CARVING IRISH BOG-OAK. Although the interest which attaches to the substance known as Irish bog-oak, or bog-wood," is naturally more keen in the Sister Isle than in our own portion of the United Kingdom, it is probable that a better acquaintance with this remarkable product of nature would kindle at least a fair amount of interest here if its useful applications were better known. The bogs of Ireland, besides yielding turf or peat of most excellent quality for fuel, are remark- able for the large quantity of semi-petrified timber which lies beneath their surface, apparently undergoing by slow degrees the process of conversion into coal. Large quan- tities of oak, as black as ebony, and in a high state of preservation, had been dug out of the Bog of Allen and other bogs ; but no specific use was made of it, we believe, until some forty or fifty years ago, when it occurred to an ingenious old soldier named M'Guirck to utilize it in making certain ornamental articles, such as brooches, paper- knives, shamrock studs, etc. etc. It was many years after the introduction of bog-oak carving, however, before the art became fully developed ; and for a long time it was confined chiefly to the hands of M'Guirck's successor, a man of much ingenuity and skill, by whom many fine specimens of exquisite carving were produced, and which were readily, and even greedily, secured by the more gifted and appreciative of the Irish A 2 MECHANICAL INDUSTKIES EXPLAINED. nobility and gentlefolk of the time, whilst many illustrious visitors to the city of Dublin availed themselves of the opportunity to possess at least one specimen of the carver's work. As time progressed, however, so did the " whittlers " in bog-oak increase and multiply ; and by the time the Eebellion of 1848 had culminated in the expatriation of Smith O'Brien and the other leaders of the Young Ireland party, at least half-a-dozen fresh bog-oak carvers appeared in the field; and from that period the number steadily increased, until, as is generally the case, the art became somewhat overdone. Bad workmanship, accompanied by the frequent substitution of ebony for bog-oak, caused the pretty art to lose its individuality and its integrity at the same time. We have a pleasing remembrance of the great interest which many of the leading aristocracy of Ireland took in the manufacture of bog-oak ornaments, after the political disturbances referred to had subsided. The late Master of the EoUs for Ireland, Mr. T. B. C. Smith (or " Alphabet Smith," as he was humorously called), a man of exquisite taste and judgment, suggested many interesting designs from the antique, which were afterwards faithfully duplicated in bog-oak, to the great delight of all who beheld them. Nor was bog-oak carving, at the time we mention, confined to professional hands alone, for many amateurs, including the fair sex, sought recreation in the pleasing art, amongst whom may be mentioned the accom- plished daughters of the late Earl of Howth. Bog-oak is an exceedingly agreeable substance for carving purposes, being both hard and tough. The finest specimens are intensely black. In structure it possesses all the characteristics of ordinary oak, and may readily be distin- guished from ebony (or " African bog-oak/' as it is termed). CARVING IKISH BOG-OAK. 3 v/hen substituted for the real article, by its open grain and cellular structure. An important feature in bog-oak carving, when applied to objects of moderate dimensions, such as brooches, snuff- boxes, paper-knives, etc., is the small number of tools required. This is a great advantage to those who might desire to learn the art, but who may possess no previous knowled^je of carvino- in wood. There are few mechanical arts in which such pleasing results may be obtained with so few appliances ; but as several of the tools required for special purposes are of a peculiar form, and may not be obtainable at the ordinary tool-shops, instructions will be given to enable the student either to make such tools him- self or to have them made to his order. As a preliminary effort let us first select a piece of bog- oak free from flaws, and as close in the grain as possible. Suppose we commence with a " view brooch," as it is termed — that is, an oval brooch with a landscape or rustic scene carved on one side, with a plain or ornamental border, representing, as it were, a picture in a frame. The first thing to do is to cut a slice of the wood end-way — that is, transversely — with a tenon or circular saw, about I of an inch in thickness. With a lead pencil sketch an oval out- line, say 2h inches long by I J wide, at the best or soundest part of the wood. Having done this, a second oval is to be drawn inside the former, leaving a space of about J of an inch between the two. The view or scene is to be sketched in outline within the inner oval. Euins of old castles and other similar structures look exceedingly well for this pur- pose, and are by no means difficult, especially to those who have some knowledoe of drawing. o o Having so far designed the work, it will now be neces- 4 MECHANICAL INDUSTRIES EXPLAINED. sary to consider what tools will be required to carry the operation through all its stages: as we have said, the tools are not very numerous, but those we are about to mention are indispensable. One or two small gravers ; a lozenge-shaped graver; several small sculpters; several keen-cutting half-round files; two chisels, one ^ of an inch, and one J of an inch ; an American drill-stock and drills ; a pair of pliers ; glass-paper ; one ^-inch gouge ; small tenon saw; and oilstone for sharpening tools. An instrument termed the "dog-legged tool'' is very necessary for some purposes, and since it may not be easily procur- able we will attempt to describe an easy way of making it. Take a piece of flat, or even round, steel about 5 inches long and ^ of an inch in diameter, and having made it red-hot at one end, bend it at a right angle with the pliers, or in a vice, about | of an inch from the point. Make it red-hot again, and bend once more at a right angle about | of an inch upward from the former bend. If the steel employed be flat, a sharp face similar to that of a chisel is to be filed on the upper surface of the first bend, and the haft is to be slightly pointed and driven firmly into an ordinary graver-handle. If round steel is employed, the point must be hammered flat like an ordi- nary brad-awl, and faced as before. The next thing to do is to harden and temper the point, which is readily done thus: Make the point as hot as CARVING IRISH BOG-OAK. 5 fire will make it, and instantly plunge it into cold water ; it is thus hardened. The face of the tool should then be made bright by rubbing on a piece of emery-cloth moistened with oil, to remove oxide from the surface, and the face then rubbed on the oilstone ; now place it over the flame of a lamp, applying the heat at a spot about 1 inch from the point ; the moment the/ace of the tool assumes a straw- coloured tint, it is to be quickly plunged into cold water, when the tool will be tejnjjcrcd, and after being properly sharpened on the oilstone is ready for use. This is a very important and useful tool for producing jagged or rough surfaces in certain parts of the work to be described here- after. The cutting tools employed in bog-oak carving are to be used after the fashion adopted by engravers — that is to say, tlie handle is to be placed in the palm of the hand, and the blade, resting on the thumb, is to be propelled by the motion of the hand. A very little practice will enable the beginner to acquire the knack of handling and guiding the tools properly, upon which much of his success as a carver will depend. It is a good plan to practise the manipulation of the gravers by making straight and curved lines upon pieces of hardwood (boxwood, for instance) until the hand becomes accustomed to the movement required to force the tool forward from the palm of the hand. The gravers, chisels, and sculpters must be well sharpened on the oilstone before use, and care must be taken to preserve the form of face given to them by hold- ing the tool at a proper angle w^hen applying it to the oil- stone. Having prepared the outlined design, the next thing to do is to cut through every pencil-mark w^ith the graver, 6 MECHANICAL INDUSTRIES EXPLAINED. not too deeply, beginning with the outer oval, and so on until the sketch is completely traced with the graver. It is not necessary to do more than sketch an outline at first, as the detail must be filled in according to the char- acter of the picture to be represented, in doing which much of the wood must be cut away to produce the desired effects of perspective, light and shade, etc. This is done by drilling a series of holes throiigh the wood at the parts which have to be cleared away as not being part of the design. The object of these perforations is to render it easy to cut away with the small chisel all the wood between the border and the outer line of the sketch. Those who have not the advantage of a lathe may use the American drill-stock for the above purpose. It is well to drill as many holes as possible, by which means there will be less liability of splitting when cutting away the super- fluous wood with the chisel. This must be done very cautiously at first until an opening is made, otherwise the wood may split at its weakest part. Only ordinary care is necessary to avoid this. As soon as an opening is effected from front to back, the chisel may be applied more freely until the open spaces (representing the sky) are perfectly clear. Those parts which cannot be cleared by aid of the smaller chisel must have a narrow sculpter applied to them. Having thus far progressed, it will be advisable to cut away all the superfluous wood outside the oval margin. This may be readily done (keeping the object flat on a wooden block or bench) with the chisel, which must be held vertically, and only small fragments of the wood removed at a time, care being taken not to approach too close to the marginal boundary. A keen- cutting file will easily finish this part of the work, if great CARVING IRISH BOG-OAK. 7 care be exercised to preserve the perfectness of the out- line. To give additional effect to the border it is a good plan to bevel it from the picture, outward, which may be done either with a chisel, and subsequent smooth-filing, or with a small rasp, followed by a keen file. The border may be bevelled to the extent of about A of an inch below the outer edge. Before proceeding to carve the view, the border, outer edge, and back may be rendered smooth by means of glass-paper, finishing with the finest paper obtainable, or with paper wiiich has been frequently used. It will now be necessary to turn our attention to the view or scene to be represented, and the accompanying outline sketch of Waterloo Bridge, Connemara, wdll not be a dif- ficult subject to treat. First drill a series of holes in what w^e may call the " sky " part of the picture ; then with the smaller chisel carefully cut away all the wood between the 8 MECHANICAL INDUSTRIES EXPLAINED. outline of the picture and the inner margin of the border, taking care not to cut too close to the outline at first. When all this superfluous wood is cleared away, cut down the tower to the depth of about ^ of an inch up to the capital, which must project ; next cut the bridge h below this, so as to throw it farther back ; then cut the archway on the right of the tower at the angle depicted. The pointed rocks on the left of the picture may then be produced by sharp, irregular cuts with the flat and round sculpters, and lozenge graver, used alternately, to give the effect of per- pendicular needle-shaped rocks of irregular heights. The water may next be attempted by taking the dog-legged tool and working it backward and forward with a rocking motion, commencing at the lower line and working the tool gradually upward to the base of the bridge. The object being to produce a wavy or water-like eftect, the tool must be applied as directed all over the space repre- senting the water. It will be necessary, in order to give the effect of perspective, to increase the pressure upon the handle of the tool, so as to cut deeper and deeper when nearing the bridge. A few short horizontal cuts with the graver upon the surface of the water will give it a still more wavy appearance, if carefully done. The boulders, or large stones, on either side of the water may readily be formed by cutting facets with the chisel thus : First make a clean diagonal cut to the right, then a similar cut to the left, and a third cut above ; now follow this up by making a series of such blocks or stones of various sizes, diminish- ing in the distance — that is, towards the bridge. When this is done neatly, and with due regard to perspective and ruggedness, a very pleasing relief is given to the rest of the picture. The tree on the right of the tower may be formed CARVING IRISH BOG-OAK. 9 by first cutting the stem down about ^ of an inch, and then, with the dog-legged tool, render the upper part rough by working the tool from bottom to top, and then from side to side; now, with the same tool, dig out a portion of the wood here and there to give a tree-like form. The arch of the bridge may next be formed by clearing away sufficient wood to leave the arch open ; the bridge may, if necessary, be cut still deeper (taking care not to cut through to the back) to increase the distance, and the stonework of the bridge may be represented by short cuts with the graver. In order to add to the ruggedness of the old bridge, the surface may be scraped over with the point of a broken file applied in a horizontal position. The tower should also be roughened by scraping or scratcliing with a broken file, and when this is done, the cross, or window^, may be cut with the graver, and the castellated capital formed by aid of the small square sculpter. Having progressed thus far, the picture should be carefully examined, and all defects of drawing rectified. Bearing in mind that the tower is round, both the base and the capital must be neatly rounded to give the desired effect, and to aid tlie general effect of the picture. The border of the brooch, as we will now call it, is our next consideration, and this may be formed in many designs, one of the neatest being that shown in the sketch. After carefully filing the border to the proper shape, the face and edge may be rendered still smoother by means of very fine glass-paper. The scroll is readily formed by gently heating a small gouge, or the butt-end of an ordinary steel pen, fixed in a cork, and pressing this into the wood at the end of each curve, giving the tool a slight twist so as to form the turn of the scroll, as in the sketch. When this is 10 MECHANICAL INDUSTRIES EXPLAINED. done, a series of cross cuts made with the graver will com- plete the design, unless the carver's ingenuity suggests additional adornment. The border of the brooch may be ornamented in many other tasteful ways, and as an easy design for a beginner the following will commend itself. It will be necessary, however, to make a small tool for this purpose ; but as this is a very easy task, we will describe in a few words the way to make it. Take a piece of round steel wire about I" of an inch in diameter and 4 inches long ; file a flat surface at one. end, and slightly point the opposite end, so that it may be fixed in a handle. With a fine, small, half-round file cut three grooves from a little below the end up to its face, the grooves being equidistant. If the edges of the figure thus left on the face of the tool be neatly rounded, three leaves of a shamrock will be formed. By pressing this upon a piece of paper the form of the tool (if it has been properly made) will leave an impression perfect in its proportions. Now in employing this tool, it merely requires to be made moderately hot over a gas- flame or candle, when, if it is pressed on wood, it will leave a clear and well-defined figure of the shamrock. To orna- ment the border with this tool stamp the design at equal distances (about | inch apart) round the border, each alternate impression being to the right and the others to the left. When all the impressions are made they require to be linked together by a stalk traversing the entire border. This must be done with the graver, and it merely requires a little taste and careful handling of the tool to produce a graceful effect. From the main stalk, or stem, alternate stalklets (so to speak) may be traced, uniting the shamrocks with the main stem. The reader will soon find CARVING IRISH BOG-OAK. 11 that not only is this a very agreeable field for the exercise of artistic taste and judgment, but that in reality it requires but a very moderate amount of study and practice to produce very pleasing results. When the view brooch is finished, a simple operation will give it a brilliant and very pleasing appearance. Brush it well all over with good, strong, black ink made hot, to which a little sugar may be added. Set it aside for a short time, and again apply the ink. When nearly dry a large soft brush must be applied briskly until the whole surface of the wood, back and front, Jias been rendered perfectly bright. A very good solution for this purpose may be made with logwood-chips, nutgalls, sulphate of iron, and a little gum and sugar. Into this solution, after being boiled and allowed to cool a little, the bog-oak carv- ing may be immersed for a short time, and then treated as before. The view brooch, being now complete, may be mounted by any working jeweller, who will affix a joint catch and tongue at the back for a very moderate sum. As an additional ornament to the shamrock border previously described, an acorn pattern, placed alternately with the shamrock, looks exceedingly well. The acorn stamp for making the necessary impressions may be easily filed out of a piece of soft steel wire. Scrollwork borders are also highly suitable for the ornamentation of the framework of the view brooch, and the coil of the scroll may be readily formed by means of a small gouge made slightly hot. By pressing the gouge gently into the wood, and turning the hand slightly, a very neat and simple coil may be formed, which can be converted into a continuous scroll by means of the ordinary graver. It 12 MECHANICAL INDUSTRIES EXPLAINED. is better to trace a design in pencil upon the border before applying the necessary tools, by which means the accuracy of the design may be ensured. Leaf patterns also form very pretty borders for view brooches ; in fact, there are so many appropriate and graceful designs which may be applied to this part of the carving, that the taste of the carver will readily suggest such as will meet his require- ments. Shamrock studs are not only very characteristic, but form very pleasing ornaments for the shirt-front. These studs are by no means jdif&cult to make, and thoso who have the advantage of a lathe, and the knowledge of its use, can easily turn the studs ready for the subsequent operation of carving. Those who have not a lathe, however, may take their selected piece of bog-oak to an ordinary hardwood turner, who will have no difficulty in putting it into the required form. In turning bog-oak studs, the lower part, or button, should be of the same size as in the ordinary shirt-studs, with a pillar or stem of the usual height. The top, however, should be a little larger, say nearly twice the diameter of the button, bevelled downward at its edge, and flat at the top. Having obtained the studs from the turner, take one of them in hand, and with a blacklead pencil trace a bold, straight line across the flat face of the stud, exactly across its centre. A second line is to be traced in the opposite direction, so as to form a cross, reaching from edge to edge. The spaces between the cross are thus disposed of: One of them is to be selected, and a curved stalk is to be traced, say, tV of an inch in width. This stalk will be just below the upper segment of the circle, and this, with the two lateral divi- sions, will form the three leaves of the shamrock. Having CARVING IRISH BOG-OAK. 13 proceeded thus far, it will now be necessary to cut through the pencil outlines with a graver. The next operation is with the small :J-inch chisel to cut away the superflu- ous wood. The stalk may be attacked first by removing the wood from each side of the engraved line, taking care not to cut away more than is necessary. Now, with the same chisel cut between each segment at its outer edge, so as to slightly round each of these divisions or leaflets of the shamrock. A very little judgment will show how much of the wood need be removed to leave the form of a leaf in each division. Again take the graver tn hand, and cut a line from the outer centre of each division or leaflet down to the centre of the stud. When this is done, the form of the leaf will begin to show itself. The next thing is to cut down with the ^-inch chisel between each subdivision of the leaflets, from the outer edge to the engraved line, in each case. The cut is to be made cleanly, about xV of an inch deep at the engraved line, leaving the outer edge of the stud of its original height. When one side of the leaflet is thus cut down, the opposite side is to be cut in a similar manner, and so on until each leaflet appears sunken towards the centre. The stalk is now to be cut down to a little below the leaflet above it. With a keen but fine file now file the stalk and leaflets into proper shape, observing the most perfect accuracy in this detail (see engraving). 14 MECHANICAL INDUSTRIES EXPLAINED. In order to give the characteristic lines to each sub- division of the leaflet two tools are necessary, one for the left and the other for the right handed cut. These tools may be thus described : Take a piece of flat steel about ■^Q of an inch wide, of an inch in thickness, and about 3 inches long. As this tool requires to be fitted into a handle, it will be necessary to file away sufl&cient metal at one end to enable it to be fixed in an ordinary graver- handle. The cutting end of the tool must now be filed obliquely, so that one edge of the tool will be about ^ of an inch below the other. A series of deep lines are now to be cut with a graver, commencing at the upper edge or point of the tool, and passing downward towards the haft, to the extent of, say, | of an inch. These cuts should be rather deep, perfectly straight, and extend the whole width of the tool. Turning the tool over, it is to be faced, chisel- like, by filing down to the proper angle. Now remove the CARVING IRISH BOG-OAK. 15 tool from the handle and place it in the fire. When white-hot plunge it into cold water; after being well rubbed on emery cloth, with the assistance of a little oil, the tool may be tempered by holding the haft in a gas- flame until the point assumes an orange tint. After cooling, rub the face of the tool on the oilstone until quite sharp. It is necessary to have, as we have said, a left and right handed veining tool for cutting shamrock leaves. To accomplish this the angles of the tools must be filed in opposite directions (see engraving). In using the veining tools, hold the bog-oak stud firmly in the left hand, resting it upon the corner of a bench (or, still better, a projecting piece of wood such as jewellers employ), and having selected the proper tool, press it firmly into the wood, beginning with the half leaflet on the right of the stalk. The cuts are to be continued from the outer edge down to the engraved line in the centre of the leaflet. The tool must be used with firmness and a steady hand, so that the veins may appear perfectly sharp, distinct, and straight. The second tool is then to be applied in like manner to the other half of the leaflet, and so on until the veining is complete. The graver should now be again passed down the centre of each leaflet, so as to make a distinct partition between its two halves. As a final operation, the stalk should be bevelled from its upper surface downward by means of the chisel, and a curved line traced on the face of the stalk will relieve its flatness. The studs may be blackened and polished as before described. Fly-studs may be very easily made in bog-oak from studs turned as suggested ; and when well made, they not only form a pleasing ornament, but from their close resemblance to the notorious bluebottle, they often create a good deal 16 MECHANICAL INDUSTRIES EXPLAINED. of merriment, by being mistaken for the lively original. To make the fly-stud, trace the outline of a fly on the face of a turned bog-oak stud of the size employed for the shamrock pattern. Now cut away superfluous timber as before, and trim the edges with a file. Having cut the head into the proper form, proceed to cut out the body, a little below the wings, being careful to give it the proper shape. The wings should next be cut and rounded at their extremities, and several lines cut in them with a graver to give the veined appearance of the wing of the fly. A small tool is now required to form the eyes. This consists of a small piece of steel wire, with a hollow scooped out at one end, and which when heated and pressed upon wood, will leave a raised button-like projection. This being applied while hot to each side of the head of the fly-stud, will form the eyes very readily. In making this tool, it is a good plan to take a piece of steel wire about -J- of an inch thick, and having filed one end perfectly flat, the sculpter, or a pointed drill, will readily form the required hollow. When this is done take a fine file and file round the point, leaving a narrow margin round the hollow referred to. When the fly-stud, as far as carving is concerned, is complete, it will be necessary to drill three small holes on each side of the model for the insertion of the legs. Now take a piece of ordinarj'- iron binding wire, cut it into six lengths of about ^ inch each, and mak- ing one end of each piece of wire hot in the flame of a candle, apply a piece of shellac to the end of each. With another piece of wire, heated and dipped in shellac, apply this material to the interior of each hole in the model. By again heating the end of the six pieces of wire, and pressing them into the holes, they will become securely fixed when CASE-HAEDENINO. 17 cold. With a small pair of pliers bend each of the six pieces of wire into the proper form of a fly's leg, and the object is finished. OASE-HARDENING. When it is desired to impart a surface of steel to objects made of iron, either of the following methods may be adopted. Suppose the object to be treated is an iron key, for example. Let this be covered with grease, and after- wards well wrapped up in a piece of woollen cloth bound tightly on the key by means of thin iron wire. Now place the key thus prepared in the hottest part of a clear fire, and let it remain until all the woollen matter has burned away. The key is then to be withdrawn from the fire by means of a pair of tongs, and instantly plunged into cold water. The surface of the metal will thus have become converted into steel, and the article may be polished by means of fine emery-cloth and oil, and afterwards finished by polishing witli powdered crocus. In case-hardening iron tools and small objects required to be polished, the following method is practised on the large scale: The articles are placed in an iron box embedded in powdered charcoal; the box is then sub- mitted to a brisk heat in a furnace — the process being termed "cementation" — and the articles are afterwards immersed in cold water, and subsequently polished. Ferrocyanide of potassium is sometimes employed in the process of case-hardening. The iron article is first well polished, and is then made red-hot, and while in that state the part required to be hardened is sprinkled over with finely-powdered ferrocyanide of potassium.* * See Scientific Industries, p. 7 1>. B 18 MECHANICAL INDUSTRIES EXPLAINED. This salt becomes decomposed by the heat, and the surface of iron, after being quenched in cold water, becomes exceedingly hard, indeed so much so that a file produces no effect upon it. If small articles, or portions of them, are first made red- hot, and then dipped into powdered prussiate of potash (ferrocyanide of potassium) for an instant, and finallj dipped into cold water, the hardening effect is produced with perfect certainty and ease. Any small iron article may have a steel surface imparted to it by either of the pro- cesses mentioned with very little trouble to the operator. BRONZE-OASTING. The universal interest which attaches to those exquisite works of art known as bronzes will render a short descrip- tion of the system adopted in their production interest- ing to many readers. The following is from the pen of an intelligent American writer : — " Eeal bronze is an alloy of copper, zinc, and tin, the two latter metals forming a very small part of the combination, the object of which is the production of a metal harder than the pure copper would be, and consequently more capable of standing the action of time, and also less brittle and soft than zinc alone. " The original statuette is generally finished in plaster. The manufacturer's first operation is to have it cut in such pieces as will best suit the moulder, the mounter, and the chaser, for very few bronze statuettes are cast all in one piece. Arms and legs are generally put on after the body is finished. The next operation is to reproduce the dif- ferent parts of the figure in metal. For this the moulder BRONZE-CASTING. 19 takes it in hand to prepare the mould. He begins by- selecting a rectangular iron frame, technically termed a flask, large enough for the figure to lie in easily. To this frame, which is from 2 to 6 inches deep, another similar frame can be fastened by bolts and eyes arranged on the outside of it, so that several of these frames superposed form a sort of box. The workman places the plaster statuette, which is now his ' pattern,' on a bed of mould- ing sand inside the first iron frame. The sand used for mould-making is of a peculiar nature, its principal quality being due to the presence of magnesia. Only in one locality in the world is found the best sand, that is at Fontenay-aux-Eoses, a few miles from Paris. This sand, when slightly damp, sticks together very easily, and is well fitted to take the impression of the pattern. " Once the pattern embedded in the sand, the workman takes a small lump of sand, which he presses against the side of the figure, covering a certain portion of it. Next to this piece he presses another, using a small wooden mallet to ensure the perfect adhesion of the sand to the pattern. Each one of these pieces of sand is trimmed off, and a light layer of potato-flour dusted over both the pattern and the different parts of the mould, to prevent them from adhering together. In course of time the entire part of the pattern left above the first bed of sand on which it has been placed will be covered with these pieces of sand, which are beaten hard enough to keep together. Loose sand is now thrown over this elementary brickwork of sand, if it may be so called, and a second iron frame bolted to the first one to hold the sand together, which, when beaten down, will form a case holding the elementary sand pieces of the mould in place. The work- 20 MECHANICAL INDUSTRIES EXPLAINED. man now turns his mould over, and removes the loose sand w^hich formed the original bed of the pattern, and replaces it by beaten pieces, just as he has done on the upper side. " We can now easily conceive that if the mould is opened, the plaster pattern can be removed, and that if all the pieces of sand were replaced as they were, we shall have a hollow space inside the mould which will be exactly the space previously occupied by the pattern. If we pour melted metal into this space, it will fill it exactly, and consequently when solidified by cooling, reproduce exactly the plaster pattern. Tor small pieces this will answer very well, but large pieces must be hollow. If they were cast solid the metal in cooling would contract, and the surface would present cracks and holes difficult to fill. To make a casting hollow it is necessary to suspend inside the mould an inner mould, or ^core,' leaving between it and the inner surface of the first mould a regular space, which is that which will be filled by the metal when it is poured in. This core is made of sand, and suspended in the mould by cross wires or iron rods, according to the importance of the piece. A method often used in prepar- ing a mould, named by the French cire perdue, will .help to illustrate this. The artist first makes a rough clay image of the figure he wants to produce. This will be the core of the mould ; he covers it with a core of modelling wax of equal thickness, and on this wax he finishes the model- ling of his figure. The moulder now makes his sand- mould over the wax, and when it is completed, by baking the mould in a suitable furnace, the wax runs out, leaving exactly the space to be filled by the metal. The celebrated statue of Perseus, by Benvenuto Cellini, was cast in this BRONZE-CASTING. 21 'way, and it is very frequently employed by the Japanese and Chinese. Sometimes flowers, animals, or baskets are embedded in the mould, and after the baking, the ashes to which they have been reduced are either washed or blown out to make room for the metal. This can easily be done through the jets or passages left for the metal to enter the mould, and through the vent-holes provided for the escape of air and gases. " When the mould has cooled, it is broken to remove the casting it contains, and here is the reason why real bronze is so much more expensive than the spelter imitation. For each bronze a new sand-model must be made, w^iile the zinc or spelter can be poured in metal moulds which will last for ever. In this way the pieces are produced with little more labour than that required to manufacture lead bullets. These pieces, of course, do not require the same expensive finish as the real bronzes. When the casting is taken out of the mould it goes to the mounter, who trims off, files the base true, prepares the sockets which are to receive the arms or other pieces to be mounted, and hands tlie piece to the chaser. The work of this artist consists in removing from the surface of the metal such inequalities as the sand-mould may have left, and in finishing the surface of the metal as best suits the piece. The amount of work a skilful chaser can lay out on a piece is unlimited. In some cases the very texture of the skin is reproduced on the surface of the metal. This mode of chasing, called in French chaire, and in English "skin- finish," is of course only found on work of the best class. Sometimes pieces are finished with slight cross touches similar to the cross-hatching of engraving. This style of linisli, which is much esteemed by connoisseurs, is termed 22 MECHANICAL INDUSTRIES EXPLAINED. 'cross-riffled/ or riboute. After the chaser has finished his work, the piece returns to the mounter, who definitely secures the elements of the piece in their places. " The next process is that of bronzing. The colour known as ' bronze ' is that which a piece of that metal would take through the natural process of atmospherical oxidize- ment if it were exposed to a dry atmosphere at an even temperature. But the manufacturer, not being able to wait for the slow action of nature, calls chemistry to his aid, and by different processes produces on the surface of the piece a metallic oxide of copper, which, according to taste or fashion, varies from black to red, which are the two extreme colours of copper oxide. The discovery of old bronzes, buried for centuries in damp earth, and covered with verdigris, suggested the colour known as vert antique, which is easily produced on new metal by the action of acetic or sulphuric acid. In the fifteenth century the Florentine artisans produced a beautiful colour on their bronzes by smoking them over a fire of greasy rags and straw. This colour, which is very like that of mahogany, is still known as a Florentine or smoked bronze/' ANNEALING GLASS. Baron Albert and Mr. J. M. A. Weyer's process consists in burying the articles to be annealed in powdered stone, plaster, lime, fireclay, etc., or in grease, oil, the fused nitrates of potash and soda — in fact, any liquid or solid capable of receiving the required heat, and remaining in a condition suitable for the process. By this means glass articles are not only rendered more capable of sustaining sudden transitions of temperature, but they are also ANNEALING GLASS. 23 strengthened to a considerable degree. Thus champagne- bottles made by the processes at present in vogue are unable to sustain a higher pressure than thirty atmospheres, but when annealed by the new method, they will with- stand fifty atmospheres. Lamp chimneys may also, when highly heated, be plunged into cold w^ater without any danger of cracking. The method of embedding the articles in powder renders it possible to anneal at a very high temperature, which is impossible unless some means are provided for supporting the articles and maintaining their shape when reduced to the softened state necessary to secure perfect annealing. By the new process the articles are filled with the powdered stone or other substances, and are then placed in crucibles and completely surrounded with the pulverized substance employed, being covered to a depth of at least 2 inches. The crucibles are then sub- jected to a heat gradually increasing to 800° C, or even to 1000° C, in a suitable oven for from four to six hours, and are then slowly cooled, the operation lasting for twenty-four hours when the articles are thick. Where there is little danger of spoiling the shape of the articles the method of annealing by use of liquids gives similar results more rapidly and at a less cost. In carrying out this process two boilers are employed, so placed that the liquid can be run from the upper into the lower. If nitrate of soda is employed the temperature will be over 260'' C. before the salt is melted, and the articles are then immersed in the cold state, and the temperature raised in that case to 300"" C, the highest degree possible with nitrate of soda. They are then allowed to cool slowly, and when the temperature approaches 260° C, or solidification point, the nitrate is run off into the lower boiler, and a small fire is maintained 24 MECHANICAL INDUSTRIES EXPLAINED. beneath the upper boiler to prevent the too rapid cooling of the glass. By this process the articles are said to be perfectly annealed without injury to the surface or the shape. MORTARS AND CEMENTS. The well-known cement called " mortar," so largely used for building purposes, is composed of quicklime, sand, and water. Eiver or pit sand only should be used, and stone- lime in preference to chalk-lime for making the finest mortar. Since the stability of our dwellings depends greatly upon the quality of the mortar employed in brick- laying, it would be well if that ubiquitous individual, the much-dreaded District Surveyor, were in all cases to cast his terror-provoking eye upon the messes too frequently employed as binding material for bricks under the style and title of " mortar." It is true that while thus engaged, his valuable time would be less at the disposal of those who, without giving the formal notice and the formal fee, dare to erect summer-houses within so many feet of an ordinary dwelling-house. Hydraulic mortar, or Roraan cement, is employed in the construction of walls and piers which are exposed to water. For the purpose of making this cement certain qualities of limestone are employed, which contain in their composition silica, magnesia, alumina, etc. The native limestone is thoroughly calcined, and is after- wards reduced to a fine powder. When moistened with water a paste is formed which hardens under water, and resists the action of that element for an indefinite period. The substance chiefly used in England for making Eonian cement is that which is commonly called cement- MORTATtS AND CEMENTS. 25 stone. It is found in the argillaceous strata which occur ahernately with the limestone beds of the Oolitic formation on the coasts of Kent, Yorkshire, Isle of Wight, etc., and sometimes in London clay. Tlie clay strata above the chalk sometimes yield the nodular concretions called oolites, or cement-stones ; tliey are commonly of a yellow, grey, or brownish colour, and are sometimes composed of lime, magnesia, manganese, protoxide of iron, silica and alumina, or clay. Tlie stones are calcined in kilns, and atterwards ground to a fine powder, sifted, and finally packed in casks. When required for use, the cement is generally mixed with fine sharp sand, worked up into a thick paste with water, and used immediately, or before it has time to become hardened. The cenu^nt is much employed in the i'ormation of embankments, and for protecting walls from the effects of moisture. Portland cement, so called from the district in whicli tli(j mateiial is found, consists in calcining a mixture of limestone and argillaceous — that is, clayey — earth, and afterwards grinding and sifting the powder. It is necessary to exclude this cement from the air, other- wise it soon loses its power to set in a hard concrete mass ;ifter being mixed with watrr. I'crtland cement is much used in the preparation of concrete," a mixture of the cement with small pebbles, slightly moistened with water. This cement may fairly be considered one of tlie most important aids to the construction of permanent buildings, more especially when apjdied in the form of cuncnte to the foundations of dwelling-houses — a purpose, by-the-by, to wliicli It is unfortunately but too seldom applied. For coating walls exposed to damp, about 2 parts of cement 26 MECHANICAL INDUSTRIES EXPLAINED. to 3 parts of sand are commonly employed. Ordinary " compo'/' or Eoman cement, as it is sometimes called, is used for facing houses, cisterns, walls, etc. Steam-boiler cement is prepared by mixing litharge (powdered), 2 parts ; finest sand and quicklime, of each 1 part. The lime should be allowed to slaken spontan- eously. The cement must be kept in a closely-covered vessel. When required for use it is mixed up into a paste with boiled linseed oil, and is employed for stopping cracks in boilers and ovens, for securing steam -joints, etc Dihl waterproof cement is composed of porce- lain clay, or pipeclay, dried at a gentle heat, powdered, and mixed up into a paste with boiled linseed oil, with sometimes the addition of a little oil of turpentine. It may be coloured by adding small quantities of red or yellow ochre, etc. It is sometimes used to cover the roofs of verandahs, and for other useful purposes. Engineers' cement. — Equal parts of redlead and whitelead, worked up to a proper consistence with boiled linseed oil, forms a composition much used by engineers for securing pipe-joints, etc. It is commonly the practice to smear thin lengths of tow or hemp with the mixture, and to twine this round the thread of the pipe, the second pipe to be united is then screwed tightly on to the first until the junction is complete. It is seldom that a joint thus made needs further attention for many years. It is said that cisterns made of square stones and united with this cement seldom if ever leak or get out of repair. Fireproof cement. — Mix into a thin paste fine river-sand, 20 parts; litharge (oxide of lead), 2 parts; quick- lime, 1 part, with suflBicient linseed oil. If applied to walls PRINCE RUPERT'S DROPS — ETCHING ON GLASS. 27 it soon becomes exceedingly hard, and forms a very durable coating. PRINCE RUPERT^S DROPS. These interesting trifles are formed by allowing melted glass to drop into cold water. The drops, or glass tears, as they are sometimes called, are of a pear shape, broad at one end and tapering to a very thin tail at the other. If a part of the tail be snapped off, the whole flies into fragments with a loud explosion. The tail, however, may be cut away by a giasscutter's wheel, or the thicker end of the drop may be struck with a hammer without sustaining injury. When heated to redness, and afterwards allowed to cool gradually, the remarkable properties referred to do not manifest them- selves ; indeed the drops do not then differ from ordinary glass. "Prince Eupert's drops" may generally be seen in the shop windows of the scientific glassblowers in the neighbourhood of Hatton Garden. ETCHING ON GLASS. Indestructible drawings on glass are made by a cold clieniical process, by etching with diluted hydro-fluoric acid, first covering the places not to be eaten away with an acid- resisting material. The fluoric acid dissolves the glass without affecting the appearance of the parts protected. In consequence, the drawing or design appears slightly opaque. The desired effect is then obtained by mechanical means. The elevated parts are ground rough, so that the alternate rough and smooth portions form the picture. The drawings must be etched deep, in order to avoid the deep lines in the mechanical work. It is necessary that all parts which are 28 MECHANICAL INDUSTRIES EXPLAINED. to become opaque must be covered with the coating, in order to avoid their destruction by the fluoric acid. A new process described by Herr Gruene avoids all the difficulties surrounding the present process of etching, and enables the workman to stamp, mark, and ornament glass as if it were paper. The principle applied is as follows : The quality of the fluoric acid used is the same as in the old process, but the drawing is no longer made with a substance absolutely proof against the acid, but with another protecting the glass only to a certain point of time, thus showing in the drawing the elevated marked opaque appear- ance. For such a covering almost all the lacs, old varnishes, greasy printing dyes, etc., except the solutions of asphaltum, gutta-percha, and caoutchouc, can be used. If applied thin, they yield to the concentrated fluoric acid, even after a few seconds, no matter how firmly dried they may have become. If the substances for covering are used simply for the above- named purposes, they yield only a very feebly-marked design, partly marked and partly blank ; but if dusted after application with a finely-pulverized powder of metal, copal, or any other substance capable of rendering longer resistance to the fluoric acid, the opaque drawing is obtained directly. This is the essential point of the invention. For practical use the following advantages become apparent: 1. As the etching is rapid and not deep, no special protection of the surface by coating with acid- resisting material is necessary. 2. As only slightly- resisting covering substances are necessary, the workman can use not only brushes, gravers, pens, and patterns for drawing purposes, but can also easily make transfers from all typographical, lithographical, copper, zinc, glass, and other prints. In like manner elastic stamps and forms can MANUFACTURE OF LEAD SHOT. 29 readily be used. As one can use, ad libitum, thicker or thinner coats, as well as apply coarser or finer powder for dusting, the opaque parts can be produced in any grain desired. In one and the same etching graded designs with proportional shades can also be produced. The practical execution of this style of etching is carried out as follows : The article to be decorated receives the drawing by hand, stamp, or, as the case may be, by transfer. For the material choose an oily lac mixed with a little paint, so as to show on the glass. This done, dust in the powder. When dry, dip the part with the drawing into the fluoric acid, or put the latter on with a brush, and allow to remain a few seconds, or until the powder begins to come off; then rinse with water. The greasy substance need not be removed, as the fluoric acid absorbs it. MANUFACTURE OP LEAD SHOT. After many failures in the manufacture of lead shot, it was discovered that the chief cause of the irregularities in form which the shot exhibited were due to the too sudden cooling of the metal. This was subsequently overcome by constructing shot-towers of considerable height, as, for example, the old square shot-tower near Waterloo Bridge, London, and the more recent structure, the round shot- tower in the same vicinity. In preparing the metal for shot-making, about 3 lbs. of arsenic are added to each 1000 lbs. of soft lead. When inferior lead is used, about 8 lbs. of arsenic per 1000 lbs. of lead is employed. The arsenic is added gradually to the molten metal, with which it is allowed to 30 MECHANICAL INDUSTRIES EXPLAINED. become thoroughly alloyed. The importance of adding arsenic to the lead will be seen when it is stated that if the shots appear lens-shaped, it is owing to the arsenic being in excess ; if, on the other hand, they are flattened upon one side, if they are hollowed in the middle, or have a tail, the proportion of arsenic has been insufficient. Among the many patented processes for shot-making may be selected the following : " Melt a ton of soft lead, and sprinkle round its sides, in an iron pot, about two shovelfuls of wood ashes, taking care to leave the centre clear; then put into the middle about 40 lbs. of arsenic to form a rich alloy with the lead. Cover the pot with an iron lid, and lute the joints quickly with loam or mortar to confine the arsenical vapours, keeping up a moderate fire to maintain the mixture fluid for three or four hours ; after which skim carefully, and run the alloy into moulds to form ingots or pigs. The composition thus made is to be put in the proportion of one pig or ingot into 1000 lbs. of melted ordinary lead. When the whole is well combined, take a perforated skimmer and let a few drops of it fall from some height into a tub of water. If they do not appear globular, some more arsenical alloy must be added." Several tons of the metal are generally melted at a time in large establishments. After a time the surface of the lead becomes coated with a layer of oxide, of a spongy nature, and this is used to cover over the bottom of the cullender, to prevent the lead from running too rapidly through the holes, and thus forming oblong spheroids. The cullenders employed in " granulating the lead are hollow vessels made of sheet iron about 10 inches in diameter, perforated with holes of uniform size for each MANUFACTURE OF LEAD SHOT. 31 cullender. Cullenders perforated with various-sized holes are employed for the different kinds of shot. These holes vary from -5^ to of an inch. The process is conducted with three cullenders at a time, which are kept apart from each other by burning charcoal to keep the metal at the proper temperature. For the smaller shot a fall of 100 feet is required before the shot reaches the water-tub below. The larger shot requires a fall of at least 150 feet. The workman having put the filter-stuff into the cul- lender, fills an iron ladle with the molten metal, and pours it slowly into the cullender. Sometimes the three cul- lenders employed may have holes of different sizes, in which case the shot which falls into the tub will vary in size. These are afterwards separated by means of square sieves perforated with holes corresponding with those in the cullenders. These sieves are placed above one another, by which the larger shots remain in the sieve above, while the other sizes are retained by the sieves below. The shot has next to be sorted as to form, by which the spheroids which are not truly round, or may be other- wise defective, are separated. For this purpose the shot is placed, a handful at a time, on a board with upright ledges on each side, which is slightly inclined, and gently shaken, by which means the round shot rolls away into a vessel beneath, while those of irregular shape remain on the sides of the tray; these latter are put aside to be remelted. The shot is finally polished by being placed in a small octagonal cask, turning upon a horizontal axis, which is set in motion by steam-power. Plumbago, or blacklead, is put into the cask with the shot to aid in the process of polishing and rendering the shot smooth. 32 MECHANICAL INDUSTRIES EXPLAINED. METAL-SPINNING. Spinning is a term employed in sheet-metal work to indicate a process of drawing and shaping, which in many of its features resembles the operation of turning in wood etc. A lathe is employed, by which a metal blank and a " chuck " are rapidly revolved, and the shape is imparted to the metal by the pressure of a blunt tool. The metals used in spun- work are sheet zinc, copper, brass, and some of the soft and ductile alloys. In the manufacture of sheet-metal cornices and other decorative work for buildings, spun-work forms an import- ant feature, being used both in the principal parts and for purposes of ornament. The metal used for this purpose is ordinarily sheet zinc, although occasionally copper and brass are employed. The chucks are turned from gum, apple, cherry, or other tough or close-grained woods, for ordinary qualities, but where a very large number of a pattern is required metal chucks are employed. For large shapes, wood is employed exclusively. In using wood chucks green timber is generally preferred, on account of its greater solidity, absence from seasoning cracks, and from its being more easily turned to shape. When a wood chuck is taken off the spindle for any purpose, with the expectation of using it again, it is preserved during the interval either by immersion in water or by burying in wet shavings or moist earth. The greatest care is necessary in the use of wood chucks, except when very few pieces of a kind are required, to preserve them both from seasoning or shrinking, and from being reduced in size by the careless use of the trim- ming tool employed upon the metal. For metal chucks METAL-SPINNING. 33 cast iron or cast zinc are employed. The latter possesses advantages over the former in the convenience of casting with the common appliances of the workshop. While cast iron can be obtained only by ordinary foundry pro- cesses, necessitating delay, it possesses the compensating advantages of wearing longer, producing smoother and more accurate work, and costing less. In lamp and other similar work the art of metal-spin- ning has been developed to a very high degree. By means of compound chucks, or those which are constructed in sections and locked together with a key which provides a means of withdrawing this from finished work, forms are produced from one piece of metal, having alternate ridges and depressions, neck-shaped like bottles, which on casual inspection appear marvellous. In small articles of this nature, brass is very generally employed. Eepeated anneal- ing is required during the process, and great skill in the operator is essential. In large articles equally unexpected results by this manipulation are produced, altliough differing very much from those just described. In large forms, like those used for the borders of centre-pieces for the ceilings of rooms, and for similar purposes, which are ordinarily produced only by the aid of several seams, the expert spinner, by the use of several chucks with the same blank, first applying one side toward the chuck and then the other, as the forms to be made are either projections or depressions, will produce all the elements of an intricate moulding in one piece. The lid or cover, as of a bucket or water-cooler, together with the rim which fits into the neck and its projecting edge, are made in one piece also. Both of these examples are produced in ordinary sheet zinc. c 34 MECHANICAL INDUSTKIES EXPLAINED. In the process of zinc-spinning, frequent annealing is necessary. The appliances for this are an open charcoal fire, a gas jet, a flame from gasoline, or an annealing oven constructed upon the same general principle as employed in zinc-stamping. This may be described as a flame- encircled box, which, in its situation and arrangement, in some respects resembles the oven in an ordinary cooking- stove, into which are laid the blanks in piles. The heating process is slow, but a pile of blanks once brought up to the proper temperature retains its heat for a com- paratively long time, even when removed from the oven. Spun-metal work, besides being employed in cornice- work, lamps and lanterns, as above mentioned, enters into the trimmings and decorations of gas-fixtures, lightning- rods, weather-vanes, spire ornaments, and finials. It is used extensively in the manufacture of plated ware, water- coolers, spice-canisters, bird-cages, and many other articles. The use determines the metal employed, the process of manipulation remaining substantially the same in all. CUTLERY. The manufacture of cutlery is not only one of the most important, but probably one of the most successful, of our mechanical industries. There are three kinds of steel employed in the manufacture, namely, cast steel, shear steel, and what is called common steel. Edge-tools, which require to possess tenacity without excessive hardness, are made from shear steel, which is exceedingly tough and pliable. Table-knives, shears, scissors, scythes, etc., are made from this kind of steel, while razors are usually made from cast steel. CUTLERY. 35 In making table-knives, the first operation is termed forging ; this is generally conducted by two workmen. The blade is first roughly formed and then cut to a certain length, after which it is welded to a rod of iron about | inch square in such a way that very little of the iron is visible upon the blade. A certain portion of the iron rod, now welded to the blade, is next taken off to form the shoulder and tang, and in order to make the former of the proper size it is placed in a die, and a " swage " passed over it ; the "striker" then gives a few smart blows, by which the shoulder becomes neatly fashioned. The blade is now again heated and finished on the anvil; it is afterwards made red-hot, then plunged into cold water, by which it becomes hardened, and is finally teinjjered by gentle heat until it assumes a blue colour. It is then ready for the operation of grinding, which is effected by means of emery-wheels kept in motion by steam-power. Ordinary table-knives are made by cutting the blades out of sheet steel, and the backs, shoulders, and tangs, made of wrought iron, are welded together at a forge. The after operations are the same as those above described. In the United States, table-knives of excellent quality are made almost entirely by machinery, and at prices far below those of Sheffield manufacture. Indeed this town, so long and creditably known for the excellence of its cutlery, has suffered greatly by the influx of American cutlery, much in the same way that many of our arts have suffered — by unreciprocated free-trade. Fork-making is a separate branch of the cutlery trade, and knife-manufacturers purchase them, ready for fitting into the handles, from the forkmakers. The process of making steel forks may be thus briefly described : Steel 36 MECHANICAL INDUSTRIES EXPLAINED. rod, about ^ of an inch square, is employed, the shank and tang of the fork being first forged into shape, after which the fork is cut off, leaving about 1 inch of the square steel at one end ; this part is next drawn out flat to the required length of the prongs. The shank and tang are now heated and fashioned to the proper shape by- means of a die and swage. The prongs are next formed at a blow by means of a heavy stamp, after which the insides of the prongs are filed ; they are then bent to their proper shape, and hardened as before described, being finally tempered by applying gentle heat. Penknives are commonly forged by one person only. A rod of steel is taken, and the blade of the knife forged out to the proper length, after which this is cut off from the rod, sufficient steel being retained to form the joint. The blade is now held in a pair of tongs and subjected to heat, after which the joint is finished. After another heating, and hammering on the anvil, the blade is finished ; but while still hot the "nail-hole," by which the knife is opened, is formed by means of a chisel flat on one side and round on the other. To harden the blades, they are first made red-hot, and then plunged into cold water as far as the shoulder, after which they are placed, on their hacks, upon an iron plate, and heated until the surface of the steel assumes an orange-brown colour. Eazors are forged from cast-steel rods about J inch wide and of a thickness equal to the back of the razor, and the anvil used is somewhat rounded at its sides, by which the edge may be rendered thinner than the other parts of the blade. The tempering of razors, after hardening, is not pushed so far as for penknives, a pale-straw colour being the most suitable tint at which the operation CUTLERY. 37 should be checked by cooling (see Hardening and Temper- ing), Dr. Ure thus describes the interesting art of scissor- making, and the subsequent processes of grinding and polishing articles of cutlery : — " The forging of scissors is wholly performed by the hammer, and all the sizes are made by a single hand. The anvil of the scissor-maker weighs about cwt. ; it measures, on the face, about 4 by 11 inches. It is provided with two gates or grooves for the reception of various little indented tools termed by the workmen bosses. One of these bosses is employed to give proper figure to the shank of the scissors; another for form- ing that part which has to make the joint; and a third is made use of for giving a proper figure to the upper side of the blade. There is also another anvil placed on the same block, containing two or three tools called beak-irons, each consisting of an upright stem about 6 inches high, at the top of which a horizontal beak pro- jects. One of these beaks is conical, and is used for extending the bow of the scissors ; the other is a segment of a cylinder with the round side upwards, containing a recess for giving a proper shape and smoothness to the inside of the bow. " The shank of the scissors is first formed by means of one of the bosses above described, leaving as much steel at the end as will form the blade. A hole is then punched about \ of an inch in width, a little above the shank. The blade is drawn out and finished, and the scissors sep- arated from the rod a little above the hole. It is heated a third time, and the small hole above mentioned is extended upon the beak-irons so as to form the bow. 38 MECHANICAL INDUSTRIES EXPLAINED. This finishes the forging of scissors. They are promis- cuously made in pairs. They are next annealed for the purpose of filing such parts of them as cannot be ground, and afterwards paired. " Very large scissors are made partly of iron, the blades being of steel. "After the forging, the bow and joints, and such shanks as cannot be ground, are filed. The rivet-hole is then bored, through which they are to be screwed or riveted together. This common kind of scissors is only hardened up to the joint. They are tempered down to a purple or blue colour. In this state they are taken to the grinder. " Grinding and polishing of cutlery. — The various pro- cesses which come under this denomination are performed by machinery, moving in general by the power of the steam- engine or water-wheel. " Grinding-wheels or grinding-mills are divided into a number of separate rooms ; every room contains six places called troughs ; each trough consists of a convenience for running a grindstone and a polisher at the same time, which is generally occupied by a man and a boy. " The business of the grinder is generally divided into three stages — viz. grinding, glazing, and polishing. The grinding is performed upon stones of various qualities and sizes, depending on the articles to be ground. Those expos- ing much flat surface, such as saws, fenders, etc., require stones of great diameter ; while razors, whose surface is concave, require to be ground upon stones of very small dimensions. Those articles which require a certain temper, which is the case with most cutting instruments, are mostly ground on a wet stone ; for which purpose the stone hangs within the iron trough, filled with water to such CUTLERY. 39 a height that its surface may just touch the face of the stone. " Glazing is a process following that of grinding. It con- sists in giving that degree of lustre and smoothness to an article which can be effected by means of emery of the various degrees of fineness. The tool on which the glazing is performed is termed a glazer. It consists of a circular piece of wood, formed of a number of pieces in such a man- ner that its edge or face may always present the endway of the w^ood. Were it made otherwise, the contraction of the parts would destroy its circular figure. It is fixed upon an iron axis similar to that of the stone. Some glazers are covered on the face with leather, others with metal consist- ing of an alloy of lead and tin ; the latter are termed caps. In others, the wooden surface above is made use of. Some of the leather-faced glazers, such as are used for forks, table- knives, edge-tools, and all the coarser polished articles, are first coated with a solution of glue, and then covered with emery. The surfaces of the others are prepared for use by first turning the face very true, then filling it with small notches by means of a sharp-ended hammer, and lastly fill- ing up the interstices with a compound of tallow and emery. " The pulley of the glazer is so much less than that of the stone that its velocity is more than double, having in general a surface speed of 1500 feet in a second. "The process of polishing consists in giving the most perfect polish to the difierent articles. Nothing is sub- jected to this operation but what is made of cast steel, and has been previously hardened and tempered. "The polisher consists of a circular piece of wood covered with buff leather, the surface of which is covered from time to time, while in use, with crocus. The 40 MECHANICAL INDUSTRIES EXPLAINED. polisher requires to run at a speed much short of that of the stone or the glazer. Whatever may be its diameter, the surface must not move at a rate exceeding 70 or 80 feet in a second." CRAYONS. These " coloured chalks/' as they are sometimes called, are prepared from pipeclay, or China clay, with the addi- tion of certain mineral or metallic pigments. In Paris crayons are prepared from the following mixture : Shellac, 6 parts; spirit of wine, 4 parts; turpentine, 2 parts; colouring powder, as vermilion, Prussian blue, orpiment, etc., 12 parts ; blue clay, 12 parts. The clay is well mixed up with water, and after allowing it to stand for a few seconds, the liquor holding the finest particles in suspension is poured off, and this is allowed to settle. The clear water is after- wards poured off, and the pasty mass carefully dried. The shellac, after being dissolved in the spirit of wine, is to be incorporated with the dried clay, colouring powder, and the turpentine, until the whole assumes the consistence of putty. The careful mixing of the ingredients is of great importance, in order to ensure uniformity. When the mixture is complete, the mass is pressed into suitable moulds to give the crayons the proper form, after which they are carefully and gradually dried in a stove or oven. Bright red crayons may be made by reducing red hematite (native peroxide of iron) to a fine powder, and separating the finer particles by washing, as above. The resulting red mass is then to be made into a thick paste with gum- arabic and a little curd or Castile soap, and is afterwards moulded by forcing it through a syringe, and then dried CRAYONS. 41 into crayons. Care must be taken not to employ an excess of gum, otherwise the crayons will be too hard to produce the required tracings on paper. Crayons of very good quality may be made by the amateur by simply working up into a paste, with a little pale ale, ordinary pipeclay, with the addition of any metallic or earthy colouring matter, as yellow ochre, red ochre, orpiment, lemon chrome, orange chrome, vermilion, sap green, powdered Prussian blue, blue verditer, etc. In order to make crayons of the various shades and tints of colour required for chalk-drawing, it is necessary to mix the colouring matters in due proportions with the pipeclay; thus the varied shades of green must be prepared by mixing blue and yellow, the addition of vandyke or other browns being employed to produce the darker tints of green. When it is borne in mind that crayon colours cannot be mixed, like water or oil colours, at the time of using them, it is necessary to have at least three or four shades of each colour always at hand, so that the artist may produce any desired effect. Black crayons may be prepared from lampblack, ivory black, or blacklead. Good charcoal, cut into the suitable form, is frequently used as a crayon in this class of drawing. If any of these ingredients, in fine powder, are mixed with melted wax, they form excellent black crayons. Brown crayons may be made from burned or raw sienna, burned or raw amber, etc.; carmine and black may be added to give certain peculiar tints occasionally required. For various tints of red, carmine and carminated lake may be mixed with pipeclay, or prepared chalk, with or without the addition of a little eum. o King's yellow, Naples yellow, yellow ochre, etc., are also used in making yeUow crayons. 42 MECHANICAL INDUSTRIES EXPLAINED. MANUFACTURE OP TIN-PLATE. Sheet iron, previously prepared, is dipped into a bath of melted tin, by which it becomes coated with that metal, forming the so-called "sheet tin," or tin-plate, of com- merce. The process of manufacture is conducted some- what as follows: The sheet iron is first cut into certain sizes ; it is then cleansed from the " scale," or oxide, which occurs on its surface in the process of manufacture, after which the plates, as they are called, are dipped for a few minutes in a bath composed of dilute hydrochloric acid (muriatic acid) ; they are next drained from the acid and afterwards made red-hot, by which process the scale chips off, leaving the iron tolerably clean. The plates are after- wards passed through chilled rollers, and next plunged into a dilute acid-bath made by fermenting bran-water. They are next put into a leaden trough containing dilute oil of vitriol. This " pickle," as it is termed, removes any oxide that may be upon the surface. After about an hour the plates are removed, rinsed in clean water, and well scoured with sand and water, and are then placed in clean water until required for the subsequent operation of tinning, etc. The tinning process is conducted as follows : A series of cast-iron pots are arranged over a fire flue. The first pot contains the melted tin; the second is the wash-pot; the third the grease-pot ; the fourth is the pan, with a grated bottom ; and the fifth is the list-pot. The plates are first dried in bran, and are then, one by one, dipped in melted tallow, in which they are allowed to remain for a short time; they are next removed and dipped into the tin-bath com- posed of a mixture of block and grain tin covered with a MOIREE METALLIQUE. 43 layer of tallow to prevent oxidation of the metal. The plates are allowed to remain in the molten tin for an hour or more, after which they are removed, and placed on the grating to allow the superfluous tin to run off. The next operation, called " washing,." consists in dipping the plates in a pot containing melted grain tin, which assists in re- moving the superfluous coarse tin imparted by the first process. The plates are taken out of the grain-tin pot, one by one, by means of a pair of tongs, held in the left hand, and the workman scrubs each plate with a hempen brush, held in the right hand. The plate is next dipped for a moment once more in the wash-pot, and afterwards in the grease-pot. Great care is necessary to keep the grease at the proper temperature, by which the brightness of the plates, as they come from the metal-pot, is maintained. The plates are finally cleansed from the tallow by being rubbed with bran ; they are afterwards packed in boxes, each box containing 225 plates. MOIREE METALLIQUE. A beautiful crystalline appearance is imparted to tin plates (see p. 42) by the action of dilute acids. Under the title of moiree metallique the art of ornamenting tin at one time attained great popularity, and indeed at the present day it is mucli practised both in this country and on the Continent. If we remember rightly, the late Sir Isambard Brunei, the gifted designer of the Thames Tunnel, patented a process for ornamenting tin by means of acid solutions many years ago. To impart to sheet tin the crystalline effects referred to, the metal is first slightly heated, after which its surface 44 MECHANICAL INDUSTRIES EXPLAINED. is gently rubbed over with a sponge dipped in an acid solution made by mixing nitric acid, 4 parts; distilled water, 2 parts ; sal-ammoniac, or common salt, 1 part. Dissolve the salt in the water before adding the acid. In a very few moments after the sponge has been applied the crys- talline appearance will be developed, when the plates should be at once plunged into clean water, and the surface of the metal may be gently brushed over with a piece of cotton wool while still under the water. The crystalline effect may be modified by sprinkling water over the surface of the plate before immersing it in water. A very pleasing effect is produced upon a piece of sheet tin by gently heating its centre by holding it over the flame of a candle for an instant — that is, until it has become moderately warm — and then passing the sponge dipped in the acid solution over the part heated. In order to add greater beauty to articles made from sheet tin, ornamented as above described, various coloured varnishes are employed; and the spangled effects of the crystalline surface, as seen through the varnish, is both pleasing and remarkable. BALLOONS. It is now nearly one hundred years — namely, in the year 1784 — since Signer Lunardi made his first balloon ascent from the Artillery Grounds in Moorfields. In the year following Messrs. Blanchardand Jeffries crossed the Channel from Dover to Calais in a balloon. From this period balloon ascents, as a source of attraction to public gardens, became more and more frequent. The elder Green, whose very BALLOONS. 45 numerous ascents from the old Vauxhall Gardens and else- where may still be remembered by many, was followed by his son, Henry Green, who was scarcely less famous in his day for the number of times he floated above the surface of the earth to "please a gaping crowd" as some ill-natured people will say. Next came Lieutenant Gale, Adams, Mrs. Graham, and the renowned Henry Coxwell, whose name has been far more scientifically associated with aeronautics, we believe, than that of any man living. Indeed, his vast experience and practical knowledge of the subject has enabled him to render great services to the British and other Governments in con- nection with the construction of balloons for war purposes. It will be within the recollection of most persons that this eminent aeronaut some years ago, in company with Mr. Glaisher of the Eoyal Observatory, ascended to an alti- tude of 61 miles ; when, owing to the highly rarefied condition of the atmosphere, Mr. Glaisher became in- sensible, while Mr. Coxwell himself became so far power- less that he was compelled to seize the valve-rope between his teeth to enable the gas to escape so that the voyagers might descend. With a desire to render the ordinary balloon safer, the author, in 1874, took out a patent for a balloon constructed in conipartmentSy so that in the event of one or more com- partments becoming injured, from gun-shot or otherwise, the remaining chambers, even to the last of them, would retain sufficient gas to keep the balloon afloat. Being anxious to obtain a practical opinion as to the utility of the new balloon, the author submitted a model of it to Mr. Glaisher, who expressed himself highly pleased with the design, and said that he considered it " a hundred times safer than the ordinary balloon." After fruitless attempts 46 MECHANICAL INDUSTRIES EXPLAINED. to induce the " constituted authorities " of the Horse Guards and others to look into the matter, the invention, like many others, was dropped. Ordinary air-balloons are made of very strong thin silk, specially manufactured for the purpose, and coated with an elastic varnish of drying linseed oil or a solution of india- rubber. The balloon is protected by a netting of strong silk or flaxen cord. The car is made of wicker-work, which, owing to its extreme lightness, is admirably suited to the purpose. Fire-balloons, as they are called, are made of tissue paper cut into gores, and pasted or gummed together. A ring of thin wire, crossed by two other wires, is attached to an opening at the bottom, and a piece of sponge is fastened to the centre of this, which, being saturated with spirit of wine or wood spirit, and ignited, soon fills the balloon (which should be held erect during inflation) with heated air. Hot air being lighter than the atmosphere, the balloon soon begins to rise — even before it is fully inflated, and so long as the air retains this degree of rarefaction the balloon will continue to float. Montgolfier constructed his first balloon on this principle, and it is not many years since a large balloon, inflated by burned shavings and straw, ascended from Cremorne Gardens. BREAD-MAKING, When we came to the letter B in the early days of our caligraphy, with what reverence we must have written Bread is the staff of life " in the hungry hours of school- time ! The best bread is made from pure wheaten flour, made BREAD-MAKING. 47 into a paste, or dough, with water, to which is added a little common salt and yeast. In the preparation of his dough the baker takes a portion of the water required for a " batch," and adds boiling water to it until it is tepid. To this he adds the salt and yeast, and a portion of the flour, the whole forming a thin dough. This is set aside for a short time in the kneading-trough, when it gradually begins to ferment and swell. After a while the mass assumes a spongy form, swelling up considerably ; it then bursts and subsides alternately, and when the baker con- siders that the i^rocess of fermentation has proceeded far enough, and before the dough becomes sour^ he adds the remaining quantity of flour, salt and water, to complete the batch, and then proceeds to knead the whole until it is sufficiently tough to bear the pressure of the hand without sticking to it. The dough is then set aside for several hours, and fermentation continues. After a while the dough is again kneaded, then cut into pieces, which are weighed, and these are next formed into loaves. These loaves, after a time, swell to nearly double their size, when they are at once placed in the oven and baked. Soon after being put in the oven the loaves attain a still greater size, from the expansion of the carbonic acid gas which is generated during the fermentation ; but eventually the outer surface becomes hardened, and the bread then retains its form and size. White bread is made from the best wheaten flour; ordi- nary wheaten bread from flour containing a little of the finest bran ; seconds bread contains a larger proportion of bran, while ordinary household bread is made from flour from which the bran has not been separated. This latter is unquestionably the most wholesome, as also the most 48 MECHANICAL INDUSTKIES EXPLAINED. nutritious kind of bread which the noble grain is capable of yielding, and it is much to be deplored that it is so little used. Indeed it has been for many years the opinion of men of science that dyspepsia has been greatly pro- moted by the continual use of bread made from flour deprived of its bran — the most nutritious part of the grain. When fashion changes, and sallow complexions cease to be admired, probably whole-meal bread — the o^eal "staff of life " — may take the place of the stuff of custom which at present usurps the place of bread. Considering the vast importance which attaches to the principal food of the community, it seems strange that those in authority should so persistently " wink at " the whole- sale adulteration and sophistication to which our daily bread is subject, at the hands of unscrupulous and selfish tradesmen and millers. When it is stated that amongst the favourite adulterants employed in the " manufacture " of bread are bone-dust, chalk, and plaster of Paris, besides potatoes, beans, and rice, it will be understood that the baker, and not the consumer? is most likely to fatten on the product. The employment of alum, as a means of producing artificial whiteness in damaged or inferior flour, has often been the subject of controversy ; but unfortunately those whose duty it is to guard the public from the pernicious trickeries of trade appear loth to interfere with the " freedom even of the most dishonest. Mr. Cooley, who had considerable experience in the analysis of bread, says: " In the manufacture of white bread from damaged or inferior flour, a large quantity of alum is employed by the fraudulent baker ; but with the best flour no alum is required. The utmost beauty, sponginess, and BREAD-MAKING. 49 sweetness may be given to bread without the addition of one particle of alum, provided the best materials alone enter into its composition. As such materials are seldom employed by the bakers, the usual practice is to introduce 4 or 5 ounces of alum to every sack of flour, or about 1 ounce to each bushel ; and very frequently fully double this qiiantity of alum is employed. But even this enormous quantity is often not the wliole of the alum present in common bread ; for the miller, in order to cheat the laker, puts in the ' doctor ' in the shape of 4 to 6 ounces of alum to the sack, whilst the baker, unconscious of this victimization, subse- quently uses a double dose of alum in order to cheat his customers^ There can be no doubt whatever that if any addition is necessary to improve the condition of inferior flour, the bicarbonate of soda would prove the most harmless, if not the most effective, ingredient. Magnesia has been recom- mended for this purpose, but we are of opinion that the continued consumption of bread laden with magnesia would soon prove highly injurious — more especially to young children, whose daily consumption of bread is often con- siderable. French bread is made from fine flour, and it is com- monly the practice, in making the better qualities of fancy bread, as rolls and small loaves, for instance, to make the dough with milk and water, with sometimes the addition of a little butter. The following directions have been given for baking this class of bread : " When the rolls, or small fancy loaves, have lain in a quick oven about a quarter of an hour, turn them on the other side for about a quarter of an hour longer. Then take them out and chip them with a knife, which will make them look spongy, and of a fine D 50 MECHANICAL INDUSTRIES EXPLAINED. yellow; whereas rasping takes off this fine colour, and renders their look less inviting." A very wholesome household bread was suggested by tlie Eev. Mr. Haggett. It is made as follows: Eemove the flake-bran from flour 14 lbs. ; boil the bran in 1 gallon of water until reduced to 7 pints ; strain, cool, and knead in the flour, adding salt and yeast as for other bread. Some years ago there was a strong desire to introduce " unfermented bread as a substitute for the ordinary bread made with yeasty or with leaven — that is, thin dough which has been allowed to undergo fermentation, or semi-putrefac- tion. One of the best formulae for the preparation of unfer- mented bread is that made from Jones' patent flour,* as follows: 'Take kiln-dried flour, 1 cwt. ; tartaric acid, 10| ounces; mix thoroughly. After two or three days add bicarbonate of soda, 12 ounces ; lump sugar, J lb. ; common salt, 1| lb.; mix, and pass the compound through the ' dressing-machine.' It is necessary that all the ingredients should be perfectly dry, and thoroughly well mixed. By simply mixing this flour with cold water and at once baking it, it produces a light, porous bread." PAPIER-MAOH^. Paper reduced to pulp by boiling in water, and the pulp afterwards strained and moulded into any desirexl form, constitutes what is termed papier-mache. Any old paper may be used for this purpose, and the articles made from the pulp may be japanned, or painted, and possess great durability and toughness with exceeding lightness. Sulphate of iron and quicklime, as also albumen, or white of egg, are sometimes added to the pulp to render the article? * Called Self-raising flour." GALVANIZED IRON. 51 made from it waterproof ; and phosphate of soda, borax, and other substances are sometimes added to render the articles non-combustible. Papier-mache tea-trays, which have long- been in vogue, are made by uniting layers of brown paper by means of paste or thin glue, and afterwards submitting them to powerful pressure. When dry, such articles become ex- ceedingly hard. A final coating of Japan varnish, with a cer- tain amount of ornamentation, completes the manufacture. Eecently, washing-basins, jugs, and other utensils have been made from paper pulp, and in the United States they are now manufacturing innumerable articles from this material. GALVANIZED IRON. The so-called "galvanized'' iron is in reality sheet iron coated with zinc. The process is conducted on a very large scale by Messrs. Morewood & Co. of Birmingham, and other large firms. The sheet iron is first placed in a " pickle " of hydrochloric acid diluted with water, or in a solution of sulphuric acid (oil of vitriol). After being in the pickle-batli about half an hour, the black scalCj as it is termed, with which sheet iron is covered, becomes loosened, and can readily be removed by scouring with sand and water, applied with hard brushes. After the plates, or iron utensils, are well pickled and scoured, they are held by the workmen by suitable tongs, and plunged into a bath of molten zinc, which, to prevent oxidation of the surface, is covered with sal-ammoniac in fine powder. When the sheets, etc., have been immersed in the melted zinc suf- ficiently long, they are carefully withdrawn, knocked against the side of the bath to shake off superfluous metal, and are then set aside to cool. Since the zinc, in this 52 MECHANICAL INDUSTRIES EXPLAINED. operation, alloys itself with the iron to a considerable extent, the sheets, if not carefnlly treated, are apt to be- come brittle, and consequently difiicult to handle without breaking. During the process of cleaning, or preparing the articles for the zinc-bath, great care is observed to examine every part of the surface, since the smallest particle of scale or other impurity on the surface of the iron would not " take " or become coated with the zinc ; and should these necessary precautions be neglected, each defective spot — especially in galvanized sheet iron which has to be exposed to the vicissitudes of weather — would ultimately lead to the destruction of that part of the object in which the flaw or imperfection existed. Indeed when a surface of iron is coated with zinc, and subjected to alternations of rain and drought, electro-chemical action becomes so vigorous at each defective part that in a very short time the more oxidizable metal (iron) becomes eaten away, and a hole is the result. It has been the practice of late years to manufacture utensils, such as cisterns, buckets, etc., of good wrought iron ; and when coated with zinc, they form exceedingly useful and cheap vessels for holding or conveying v/ater, and are largely used both at home and abroad. Galvanized-iron chains, bolts, tubes, corrugated sheet iron, gutter-pipes, and many other articles are prepared by the zincing process. GOLD-BEATING. The art of reducing gold to an excessive thinness by hammering, appears to have been known to the Eomans, GOLD-BEATING. 53 for, according to Pliny, the ceilings and walls of their dwellings were ornamented with leaf-gold. The extreme malleability of pure gold enables it to be reduced, by hammering, to a degree of thinness equal to 651,590 times greater in surface than its original size when cast. There are four distinct operations in the art of gold-beating — namely, casting the ingots, hammering, rolling, and beating. The gold is first melted in a crucible, with a little borax as a flux. When thoroughly melted it is poured into an iron mould previously made warm and greased inside. When the ingot has become solid, it is removed from the mould, and placed on a clear fire until moderately red-hot, by which any grease on the surface becomes burned off, and the metal becomes annealed, as it is termed. The gold ingot weighs about 2 ounces, and is about f of an inch in width. AVhen the ingot is cold it is passed between a pair of bright steel rollers, by which it becomes extended in length very considerably. The ribbon of gold thus pro- duced is afterwards annealed several times, and rolled out after each annealing until of such a thinness that a square inch of it weighs 6i grains. Before heatimj the gold the workman cuts the ribbon with shears into squares of about 1 inch each, taking care to have them as nearly uniform in size and weight as possible. These squares of gold are then piled up, one above another, with a layer of fine calfskin vellum placed between each strip, and about twenty extra pieces of vellum are placed above and below the pile. The pieces of vellum are about 4 inches square, and in the centre of these the pile of gold is placed. To prevent the pieces of gold from shifting their position, a band of strong parchment is 54 MECHANICAL INDUSTEIES EXPLAINED. fastened round the packet, open at each end. A short- handled hammer weighing about 15 or 16 lbs., and having a round but slightly convex face, is employed, and with this the workman strikes the packet with consider- able force, by which the gold becomes extended in width at all points. Gold-beating is conducted on a strong bench, on which is a solid block of marble about 9 inches square, enclosed in a framework, except in the front, at which a leather apron is fixed for receiving any fragments of gold which may fall from the packet during the operation of beating. The work- man is very careful to ply his hammer with great preci- sion, so as to strike the packet uniformly in the centre, and he frequently turns the packet over, so as to strike both sides equally ; and this movement is done so dexter- ously that the packet becomes reversed between every two strokes of the hammer. Occasionally the goldbeater loosens the band which confines the packet, and examines the gold so as to shift those pieces which may have been less affected by the hammer. When the leaves, after being thus beaten, have extended to near the margin of the vellum, they are removed from the packet, and each is cut into four equal squares with a knife. By this they become reduced to about the original size, though ^of course much thinner. The plates of gold are again made into a packet as before, and this time they are separated by a layer of prepared ox-gut instead of vellum. The second beating is performed with a smaller hammer than that employed in the first operation; its weight is about 10 lbs. The beating is now continued until the gold-leaf extends to the size of the skins ; but during the operation the packet has to be frequently opened to loosen GILDING WITH GOLD-LEAF. 55 the gold from the skins. The leaves are now spread on a "cushion/' and once more subdivided into four square pieces each, by means of two pieces of cane, each cut to a very sharp edge, and fastened together in the form of a cross, which is pressed down upon each leaf, whereby it becomes divided into four equal parts. These are again made up into a packet and finally beaten out to the size of ordinary gold-leaf — that is, about 3 to 3i- inches square. The leaves of gold are next made up into small books, each leaf of paper being rubbed over with red chalk to prevent the delicate gold-leaf from becoming attached to it; but before being placed in the books, the gold-leaves are first cut to a uniform size by means of a frame made of cane, with a keen-cutting edge. When this frame is pressed on the leaf it cuts it readily to the required size. A book usually contains twenty-five gold-leaves. GILDING WITH GOLD-LEAP. This is an important industry, and the purposes to which it is applied are so numerous that many distinct arts are involved in its application. Picture-frames, and other ornamental work of a like character, are generally gilt by the process which is termed oil gilding — that is, the surface to be covered with gold-leaf is first brushed over with a preparation of drying linseed oil, whitelead, and a little oil of turpentine. A second coating is then given, with a mixture of calcined redlead, unboiled linseed oil, and a little essence of turpentine. Three or four coats of this are applied to the ornamental and other parts which have to be well gilt. Gold colour, as it is called, is next applied. This is the dregs of the 56 MECHANICAL INDUSTRIES EXPLAINED. colours ground in oil which remains in the vessel in which painters clean their brushes ; it is of a sticky consistence, and after being well worked up in a pestle and mortar, or on a slab with a muller, and passed through muslin, it forms a good ground for gold-leaf. Before the leaf is applied, the gilder ascertains, by touch- ing the prepared surface with the back of his hand, whether it is dry enough to take the leaf-gold readily. The leaf is first spread on the cushion, then cut into pieces, adroitly, with the palette-knife, and pressed into its place with a tuft of cotton, or into the deeper places with a camel-hair brush. The gold is smoothed with a wide brush of camel's hair, after which it is left to dry. The gilding is next coated with a layer of spirit varnish. Burnished gilding is practised as follows : The sur- face to be gilt is first coated with several layers of whiten- ing and size, after which a coating of gold size is applied ; the gold-leaf is then laid on, and it is afterwards burnished down with an agate burnisher or a dog's tooth. Leaf-gilding on paper is done by first coating it with gum-water or fine size, and when this is nearly, but not quite dry, the leaf is laid on, and is afterwards bur- nished. The gilt lettering on bound books is simply done by laying the gold-leaf on the surface, and pressing it down with hot brass stamps or letters. The edges of the leaves of books are gilt by brushing the surface over, while in the press, with a solution of gelatine in spirit of wine, and laying on the leaf when the gelatine becomes " tacky." OR MOULU. 57 OR MOULU. The beautiful surface noticeable on French clocks and other ornamental work is produced by the process called or moiilu. The article is first gilt, and afterwards scratch- brushed with a thin paste composed of saltpetre and alum, to which is added a little hematite, or red oxide of iron. These ingredients are reduced to a fine powder, and worked up into a paste with a solution of saffron or annatto, or other colouring matter according to the tint required, whether red or yellow. When the gilding is strong, the article is heated until the coating of the above mixture curls over by being touched with a wet finger. But when the gilding is only a slight film of gold, the mixture is merely allowed to remain upon the article for a few minutes. In both cases the article is quickly washed with warm water containing in suspension a certain quantity of the materials referred to. The article is next dried without washing. Such parts as may have acquired too deep a colour are afterwards struck with a brush made with long bristles. By a series of vertical strokes with the brush the uniformity of surface is produced. If the first operation has not been successful, the colouring is removed by dipping the article in dilute sulphuric acid, and after well rinsing, the operation is repeated until the desired effect is obtained. Red or moulu is produced by employing a mixture composed of alum and nitre, of each 30 parts ; sulphate of zinc, 8 parts ; common salt, 3 parts ; red ochre, 28 parts ; and sulphate of iron, 1 part. To this may be added a small quantity of annatto, madder, or other colouring matter, ground in water. 58 MECHANICAL INDUSTRIES EXPLAINED. Yellow or moulu is produced by the following: Eed ochre, 17; potash alum, 50 ; sulphate of zinc, 10 ; common salt, 3 ; and saltpetre, 20 parts, made up into a paste as before. The dead or moulu for clocks is composed of saltpetre, 37; alum, 42; common salt, 12; powdered glass and sulphate of lime, 4 ; and water, 5 parts. The whole of these sub- stances are to be well ground and mixed with the water. Gilders' wax, for producing a rich colour upon gilt- work, is made of oil and yellow wax, of each 25 parts ; acetate of copper, 13 parts ; and red ochre, 37 parts. The oil and wax are to be united by melting, and the other substances, after being well pulverized, added gradually. MERCURIAL GILDING. Unlike electro-gilding, which is essentially a chemical operation, the process of mercury -gilding, or " wash-gilding," as it was formerly called, is chiefly mechanical in its mani- pulations. An amalgam of quicksilver and gold is first formed, and when this is applied to a surface of " gilding metal" (an alloy of copper), it becomes readily attached, and the mercury is afterwards expelled by heat, leaving a layer of gold only on the surface. The remarkable power which quicksilver possesses of dissolving gold and some other metals is thus taken advantage of in the interesting process we are about to describe. In forming the amalgam, a certain weight of standard gold is taken, and this is placed in a crucible ; when the gold has become red-hot the proper proportion of mercury is poured in. The usual proportions are about 8 parts of mercury to 1 part of gold. This mixture is carefully MERCURIAL GILDING. 59 stirred with an iron rod until all the gold is dissolved, when it is poured into a shallow vessel containing water ; after well washing the amalgam, the workman squeezes out any loose mercury that may be present, and the amal- gam is then squeezed in a chamois-leather bag, through the pores of which the unalloyed mercury oozes. The result- ing amalgam contains about 57 grains of gold and 33 grains of mercury in each 100 grains. The mercury which is squeezed through the leather bag contains a good deal of gold, and this is preserved for future use. To apply the amalgam, a solution is first made by dis- solving mercury in nitric acid, which is afterwards diluted with water. The article to be gilt is first " pickled " in a very weak solution of sulphuric acid, and then rinsed in clean water, after which it is brushed with a hard brush. It is then well dried in boxwood sawdust. A gilder's scratch-brush is then dipped in the mercurial solution and passed over a lump of amalgam, after which it is applied to the article to be gilt. This jDrocess is repeated as often as necessary. The article is then well washed with water and dried, after which it is placed in a charcoal stove and heated until all the mercury (which is volatile) is expelled. If necessary, an extra coating, or even several, is applied. Eoseleur thus describes the process of mercury-gilding as carried on in France : — " The amalgam is crystalline, and a certain crackling sound is heard when we crush the crystals between the fingers. A certain stock of amalgam is generally prepared in advance, and it is divided into small balls of nearly equal size, the value of which is ascertained from their number, and from the total Aveight of gold 60 MECHANICAL INDUSTRIES EXPLAINED. employed. Thus, if ten small balls contain altogether 5 grammes of gold, each ball will hold 0*5 gramme of precious metal. These balls are kept in water, but they should not remain too long without being used, because the phenomenon of liquation takes place, and the different parts do not present the same composition. " When using the amalgam, it is spread with the finger upon a flat, hard stone, called the gilding-stone, and having dipped a scratch-brush of stout brass wire into a solution of nitrate of binoxide of mercury until it becomes com- pletely white, it is then passed upon the amalgam, a portion of which is carried away. The object, previously well cleansed, is scratch-brushed in every direction, and the tool is often dipped into the mercurial solution in order to facilitate the regular and even spreading of the amalgam. "This operation requires great care for giving a uni- form coat upon the hollow and raised parts. " When the back part of a piece does not require gilding, the flat outline, and also the back edge, should be gilt, in order that the naked copper shall cause no injury in the subsequent operations. "When the article is uniformly covered with the amalgam, it is heated upon a charcoal fire without draught, and which rests upon a cast-iron plate. The entire attention of the operator is now required for watching the process. With his left hand covered with a thick glove of buckskin, he turns the piece in every direction upon the fire, and, as the mercury disappears, with his right hand he strikes the article in every direction with a brush, the handle and the bristles of which are long, in order to equalize the gilding, and to push the remaining amalgam upon those parts which appear less charged with it. MERCURIAL GILDING. 61 " When the whole of the mercury has become volatilized, the gilding has a dull greenish-yellow colour, resembling that of boxwood, and the operator then examines whether the coat of gold is continuous. Should a few bare places appear, a fresh quantity of amalgam is added, and the whole heated again. " The next operation is scratch-brushing, which furnishes a pale-green colour, and also requires another heating for arriving at the desired shade. The reheating should be sufficient for expelling any remaining mercury, and pro- ducing a fine orange-yellow colour. " We may now proceed to one or two distinct operations, according as we desire a bright or a dead lustre. In the first case, we submit the object, with the aid of heat, to the or-inoulu process" (p. 57). " In the second, the object is firmly fixed to an iron rod, with wire of the same metal, and smeared with a hot paste for dead gilding, composed of saltpetre, common salt, and alum. The whole is heated upon a brisk charcoal fire, without draught, and moved about until the mixture becomes dry and begins to fuse, when the article is immediately plunged into a barrel or cask half filled with water. The covering of salts is immediately dissolved, and the dead lustre appears in all its beauty. This operation, without being very difficult, requires a certain amount of practice, and a skilful work- man is sought for. The gilding must be strong to stand the dead lustre process, especially (as is often the case) when the first trial is not successful. " An object may possess the right kind of dead lustre and still be covered with red lines left by the iron wire. Tiiese disappear by plunging the object into a not too 62 MECHANICAL INDUSTEIES EXPLAINED. diluted solution of nitric acid. Pure hydrochloric acid is preferable. " The gilders with mercury do not employ pure gold ; that which they use is previously alloyed with a certain proportion of copper and silver [standard gold]. With the latter metal the gilding is green." Eed gilding is either obtained with a dark or moulu or with the formula on p. 57. LIGHTNING-CONDUCTORS. The purpose of the paratonnerre, or lightning-conductor, is to protect very high buildings from the effects of light- ning, by conducting the electric fluid to the moist earth beneath, where it will do no harm. A paratonnerre is a pointed metallic rod, the length of which varies with the height of the building to which it is applied. It is erected vertically over the object it is intended to protect, as a steeple, chimney-stack, etc. From its base an unbroken series of metallic bars, or rods soldered or welded together end to end, are continued to the ground, where they are buried in moist soil. The main parts of a well-constructed lightning- conductor are the long conducting rod referred to, which is surmounted by the conductor proper, which is sometimes formed of a conical, tapering rod of copper, the apex of which is made of platinum united by means of silver solder. For the greater security of very high chimneys it is not unusual to employ three or even four lightning-conductors, each of which terminates at its apex in a fork made of copper rod. Sometimes the extreme point of the conductor is strongly gilt by electro-deposition, in order to protect the top of the copper rod from oxidation. ' This is a very BOOKBINDING. 63 prudent precaution, inasmuch as corroded copper is a very indifferent conductor of electricity. To make a lightning-conductor on a small scale, a length of stout copper wire will answer the purpose very well. This should be fastened to the building it is intended to protect by means of ordinary iron holdfasts; the wire should be allowed to project at least 2 feet above the building, and the lower end should be sunk at least 4 feet in the soil. BOOKBINDING. The process of binding books may be thus simply described: The bookbinder receives the sheets which compose a book directly from the printer, and after having folded them in the order of the signatures, or letters at the bottom of the page, he first rolls, or beats them with a hammer, on a stone, to make them lie close and smooth. Tliey are next put into a press and sewed with hands or strips of leather fastened at certain distances, which, being all glued together very firmly, form the hack of the book, to which the pasteboards are attached by means of the bands, so as to form the sides. In this process of fixing on the sides much nicety is required in rounding the back, and kee];)ing the whole firmly fixed in the press. The book is next put into the cutting-press between two boards, one lying even with the press for the knife to run upon, the other above for the knife to run against, and thus the leaves and boards are cut to form an even edge. The next operation is the sprinkling, marbling, or gild- ing of the edges; after which the covers of leather, or cloth, having been first moistened, are cut to the size of the 64 MECHANICAL INDUSTRIES EXPLAINED. book, smeared with paste, and then stretched successively over the back and the two sides, after having taken off the four angles, and indented and platted the cover at the head band. When thus far finished, the book is covered and bound between two bands, and set aside to dry. It is afterwards washed with paste-and-water, and then sprinkled with a brush, unless it is to be marbled, which is done by making spots with vitriol. The book is then glazed with the white of egg, and lastly polished with a hot iron. The letters and ornaments are made with gilding tools, or brass cylinders, rolled along by a handle : to apply the gold, the leather is glazed with a liquor made of the white of eggs diluted with water, and when nearly dry the gold is laid on. Such is the process when a book is full hound; but books are sometimes only sewed, and have a paper cover. Sometimes the boards are covered with paper or cloth only, when they are said to be in hoards; some books have a leather covering on the back, extending a small way over each side, when they are said to be half hound. Of late years great taste has been exhibited in cloth hindings, by weaving cotton cloth in a special way for this purpose, and subsequently stamping it by means of rollers, so as to resemble the texture of leather, or any fancy pattern. Indiaruhher hinding has also been introduced, to increase the flexibility of the backs of books. MANUFACTURE OP POTTERY AND PORCELAIN. According to some authorities it was in the seventeenth century that the first small works were established in MANUFACTURE OF POTTERY AND PORCELAIN. 65 Burslem, Staffordshire, for making earthenware of a coarse description, covered with a common lead glaze ; and from that period the manufacture of pottery-ware became grad- ually extended in this county, now so famous for the magnitude of its operations. "It is to the late Josiah Wedgewood," says Ure, " that this country and the world at large are mainly indebted for the great modern advance- ment of the ceramic art. It appears that the French first gave the title ceramique to the art of pottery, the word being derived from two Greek words signifying lurned clayT The clay from which the best Staffordshire pottery-ware is made is obtained from Dorsetshire and Devonshire ; it is of a very infusible nature, and becomes exceedingly white when burned. The operation of cleansing the clay from objectionable matter, such as stones, after its removal from the pits, is conducted with much care. When required for use the clay is first cut into pieces, and afterwards kneaded into a pasty mass by steam-power. It is next placed in an iron cylinder, in which is a revolving shaft furnished with a series of blades, the effect of which is to cut the clay into very small pieces. In this state the clay is conveyed to vats, where it is worked up with water into a thin pap of a creamy consistence. The coarser particles, stones, etc., are allowed to subside, and the finer substance is then passed through a series of fine sieves made respectively of wire, lawn, and silk, and the resulting mass is then diluted with water to a certain standard density. In order to give the clay thus prepared the proper quali- ties to resist contraction and crackinGf bv the heat of the kiln in which it is baked, ground flints, reduced to a fine powder, are employed. This flint-powder is made by first 66 MECHANICAL INDUSTRIES EXPLAINED. washing the flints obtained from^chalk pits, and then cal- cining or roasting them, after which they are thrown, while still hot, into cold water. The effect of the roasting deprives the flints of their transparent character, and renders them brittle and more readily pulverizable. The finest particles of the ground flint, when carefully washed to free them from the coarser particles, form a pappy mass on subsiding in water, which is afterwards diluted with water to a given standard, and the standard clay and flint liquors are after- wards mixed together in certain proportions, according to the condition of the clay employed. The mixture is after- wards heated to expel a certain amount of its water, when the mass assumes the form of dough. This is afterwards cut into square blocks, which are piled in heaps and stored in a damp cellar for several months. During this period the "dough" undergoes considerable change, almost re- sembling fermentation in its character, and the "ware" made from it is of a finer quality than that produced from recently-made dough. When required for use the dough is taken by the work- man in both hands, and is then torn asunder, and after- wards the two pieces are slapped together with some force, the separate fragments being united in a different direction from that in which they were at first combined. This operation is repeated several times, and the lump is then dashed on a board and worked up for a considerable time until a perfectly homogeneous mass is formed. In making articles from the clay prepared as above the first operation is called throwing. This is performed on a machine called the potter's lathe, a simple form of which is given below. The flywheel is worked by a handle which sets in motion the upright spindle furnished MANUFACTUKE OF POTTERY AND PORCELAIN. 67 with a grooved pulley. The spindle being connected to the round table causes it to revolve horizontally. The speed at which the table moves is regulated by placing the driving cord on the larger or smaller grooves of the pulley. When the table is set in motion by an assistant turning the wheel, the potter takes a lump of the clay and throws it on to the centre of the table. Being provided with a vessel of water close at hand, he frequently dips his fingers ill this, and then proceeds to form the clay into a rude form suitable to the required shape of the article, and with certain wooden tools of varied forms (which are used wet) he then fashions the clay to the proper form. This opera- tion in many cases occupies but a few^ moments of time. The potter now takes a piece of thin wire, with a handle at each end, which he passes below the model and discon- nects it from the table. The vessel thus rudely fashioned is set aside to dry gradually to a certain extent ; it is then taken to a turning -lather where it is made to adhere, by being moistened, to a wooden chuck moving vertically, as in wood-turning. The vessel is now turned neatly to its 68 MECHANICAL INDUSTRIES EXPLAINED. proper shape by means of a very sharp tool, which also renders it smooth. A finishing touch is given with a steel burnisher. The condition of dryness which enables the vessel to be turned in the lathe is also suitable for attaching the handles or appendages to the vessels. The handles, etc., being previously prepared, are united to the vessel by means of a thin paste of clay called " slip," and the seams are rendered smooth with a piece of wet sponge. The vessels are next placed in a stove-room heated to about 80° or 90° Fahr. When perfectly dried, they are brushed over with a small bundle of hemp, if the articles are fine, and they are afterwards removed to the kiln, which converts the soft clay into what is termed the hiscuit. Vessels which from their peculiar form cannot be turned at a lathe, are either cast oi pressed. Press-work is effected in moulds made of plaster of Paris : one -half of the pattern is formed in one side of the mould, and the other half in the other side. Teapot handles, oval and square vessels, are made in plaster moulds. The clay is squeezed through different-shaped orifices at the bottom of a pump-barrel, by means of a piston-rod worked by a screw. The dough thus assumes a worm-shape, and is cut to the proper - length and bent to the required form. Casting is also done in plaster moulds, but the clay is worked up into a thin pap or "slip," which is poured into the moulds, after the two halves have been nicely • fitted together. The mould is thoroughly dried before the slip is poured in, and this enables it to absorb a consider- able amount of the water contained in the thin clay pap. After the thin slip has remained in the mould for a short time, during which period the clay nearest the mould has MANUFACTURE OF POTTERY AND PORCELAIN. 69 become stiff and doughy, the remainder of the thin pap is poured out, which leaves the moulded vessel hollow. The time for doing this is regulated according to the thickness required for the article being formed. It is obvious that if the clay pap only remain in the mould a very short time before the pouring out of the superfluous matter, the resulting shell, so to speak, of clay will be exceedingly thin. The cast articles thus formed are carefully dried in the " green state," as it is termed, and are afterwards united by means of slip to the vessels prepared to receive them. Imitation flowers, leaves, etc., as in Dresden china, may be produced in this way, but the operation requires, as will be readily understood, exceeding delicacy of treat- ment. Glazing consists in applying enamel^ in a semi-liquid form, to the surfaces of the stone or earthen ware, and this must, to be good, possess the same power of contraction and expansion as the material upon which it is applied. In Staffordshire three different glazes are employed ; one for common pipeclay, another for the finer quality of pipe- clay ware, to receive impressions called printing hody, and a third for ware which has to be ornamented by painting. The first glaze is composed of whitelead 53 parts, Cornish stone 16 parts, ground flints 36 parts, and flint glass 4 parts. These ingredients, excepting the whitelead, are ground to a fine powder and made into a thin paste with water. The glaze to be printed upon in metallic colours consists of white felspar 26 parts, fused or " fritted " with soda 6 parts, nitre 2 parts, and borax 1 part. To each 20 lbs. of this " frit " are added 26 parts of felspar, 20 parts of white- lead, 6 of ground flints, 4 of chalk, 1 part of oxide of tin, 70 1\IECHANICAL INDUSTRIES EXPLAINED. and a small quantity of oxide of cobalt to remove the brown tint and give a faint azure hue to the enamel. Stoneware which has to be painted is covered with a glaze composed of the above printing colour frit 13 parts, to which are added redlead 50 parts, whitelead 40 parts, flint 12 parts, the whole being well ground together. When the vessels are removed from the kiln in which they are baked, they are transferred to an apartment in which the enamel-tub is kept. They are then first dusted with a brush to remove particles of dust or grit, and are then dipped in the glaze-cream ; they are then removed by the enameller, who shakes off the superfluous enamel, and then places them in the glaze-kiln, where they are sub- jected to a heat sufficient to fuse the enamel. Ure thus describes a Staffordshire glaze-kiln, and the precautions adopted to determine the proper heat for baking the enamel : — Glaze-kiln. — This is usually smaller than the biscuit- kiln, and contains no more than forty or forty-five bungs or columns, each composed of sixteen or seventeen saggers. Those of the first bung rest upon round tiles, and are well luted together with a finely ground fireclay of only moderate cohesion; those of the second bung are supported by an addi- tional tile. The lower saggers contain the cream-coloured articles, in which the glaze is softer than that which covers the blue printed ware; this being always placed in the intervals between the furnaces, and in the uppermost saggers of the columns. The bottom of the kiln, where the glazed ware is not baked, is occupied by printed biscuit- ware. " Pyrometric balls of red clay, coated with a very fusible lead enamel, are employed in the English potteries to ascertain the temperature of the glaze-kilns. This enamel MANUFACTURE OF POTTERY AND PORCELAIN. 71 is SO rich, and the clay upon which it is spread is so fine- grained and compact, that even when exposed for three hours to the briskest flame, it does not lose its lustre. The colour of the clay alone changes, whereby the work- man is enabled to judge of the degree of heat within the kiln. At first the balls have a pale-red appearance ; but they become browner with the increase of temperature. The balls, when of a slightly dark-red colour, indicate the degree of baking for the hard glaze of pipeclay- ware ; but if they become dark brown, the glaze will be much too hard, being that suited for ironstone-waie ; lastly, when they acquire an almost black hue, they show a degree of heat suited to the formation of a .glaze upon porce- lain. " The glazer provides himself at each round with a stock of these ball watches, reserved from the preceding baking to serve as objects of comparison ; and he never slackens the firing till he has obtained the same depth of shade, or even somewhat more; for it may be remarked that the more rounds a glaze-kiln has made, the browner the balls are apt to become. A new kiln bakes a round of enamel- ware sooner than an old one, as also with less fuel and at a lower temperature. The watch-balls of these first rounds have generally not so deep a colour as if they were tried in a furnace three or four months old. After this period cracks begin to appear in the furnaces; the horizontal flues get partially obstructed, the joinings of the brick- work become loose; in consequence of which there is a loss of heat and waste of fuel; the baking of the glaze takes a longer time, and the pyrometric balls assume a different shade from what they had on being taken out of the new kiln, so that the first watches are of no comparable 72 MECHANICAL INDUSTRIES EXPLAINED. use after two months. The baking of enamel is commenced at a low temperature, and the heat is progressively in- creased ; when it reaches the melting point of a glaze, it must be maintained steadily, and the furnace mouths be carefully looked after, lest the heat should be suffered to fall. The firing is continued fourteen hours, and then gradually lowered by slight additions of fuel ; after which the kiln is allowed from five to six hours to cool." Printing under the stoneware glaze is accom- plished as follows : Cobalt blue is generally employed as the colouring matter, and the oxide of this metal is first mixed with a certain quantity of sulphate of baryta and ground flints, which are first calcined and then ground, after which the mixture is combined with a flux consisting of equal parts by weight of ground flints and flint glass reduced to fine powder. The above mixture is ground on a porphyry slab with thick boiled linseed oil, resin, tar, and oil of amber. This forms a very tenacious compound, which can only be used with the application of heat, which is done by spreading it upon a hot cast-iron plate. The printing plates, which are made of copper, are engraved with moderately deep lines. The printer spreads his colour upon the hot engraved plate, and removes any excess of colour with a palette-knife. He then takes the paper to be printed upon and soaks it in soap-and-water, and while still moist, he lays it on the engraved plate. The plate is next passed through a press, the proof-leaf is lifted off and handed to women, who cut the impression into detached pieces, which they place on the surface of the ware. The figures on the impressed paper readily become attached to the biscuit-ware, owing to the tenacious character of the varnish, and the pressure MANUFACTURE OF POTTERY AND PORCELAIN. 73 which is given, by means of a roll of flannel, by the women employed in the task. After the design has thus been fixed on the ware, it is set aside for a while to enable the colour to become thoroughly attached. The article is afterwards plunged into water, and the paper is removed with a piece of sponge, leaving the colour on the surface. After the paper is removed, the ware is dipped into caustic ley, which dissolves the oil ; it is finally dipped in the glaze-liquor, with which the figures adhere readily. The various metallic lustres which are applied to stone- ware vary according to the metal used to produce the desired effect. Platinum lustre. — Platinum is dissolved in 2 parts of hydrochloric acid and 1 part nitric acid. When the solution is cool, spirit of tar, made by boiling equal parts of tar and sulphur in linseed oil, is added, drop by drop, with continual stirring. The strength of this mixture is regulated according to the effect to be produced. When the solution is rich in platinum, the ware, coated with it, and afterwards heated in a " muffle " furnace, assumes the lustre of steel. The oxide of platinum is employed to produce a silver bistre, by brushing it evenly over the surface of the ware, after which the ware is put into the muffle-kiln; a second coating of the metallic lustre is sometimes ^iwen to heighten the effect. Gold lustre is produced by adding to a solution of chloride of gold (made by dissolving gold in aqua regia) a few grains of grain tin. A mixture is next prepared con- sisting of "balsam" of sulphur, prepared as before described, to which a little essence of turpentine is added. After being well worked up together, this mixture is to be added to the solution of gold and tin, drop by drop, with continual 74 MECHANICAL INDUSTRIES EXPLAINED. stirring. This lustre must only be applied to enamel or glaze which has already passed through the fire. Unglazed pottery.— This kind of ware, so long iden- tified with the famous name of Wedgewood, consists in mixing baryta with the clays, which acts as a flux, forming a semi- vitrified surface of great hardness. . Wedgewood ware is thus prepared : The composition of the vitrifying pastes suitable for receiving all kinds of metallic colours is sulphate of baryta, 47; felspar, 15; Devonshire clay, 26; sulphate of lime, 6 ; flints, 15 ; and sulphate of strontia, 10 parts. Gold precipitated by tin, as before, produces a rose colour; manganese, a dark-purple colour; antimony, an orange colour ; copper, browns and dark greens ; cobalt, various shades of blue ; and nickel with potash, greenish tints. The fine Wedgewood ware blue is produced by oxide of cobalt. Black Wedgewood ware is produced by the black oxides of manganese and iron. English china is sometimes composed of Cornish stone, 60 parts ; kaolin (China clay), 40 parts ; and flint glass, 2 parts : or felspar and China clay, of each 40 parts ; ground flints, 10 parts ; and flint glass, 8 parts. The glaze for the first of these compositions is felspar, 20 parts; flint, 15 parts ; redlead, 6 parts ; and soda, 5 parts. These are first " fritted" — that is, calcined without fusion — and to 44 parts of the frit are added flint glass 22, and whitelead 15 parts, the whole being well ground together. The glaze for the second composition is composed of flint glass, 8 ; felspar, 36 ; whitelead, 40 ; and ground flints, 20 parts. Porcelain. — This beautiful kind of pottery-ware is prepared from the finest kaolin, or China clay, with a siliceous flux for the hard porcelain, while the tender MANUFACTURE OF POTTERY AND PORCELAIN. 75 ware is composed of a vitreous frit made opaque by the addition of calcareous or marly clay. Artificial glass, composed of silicate of soda, or potash, and lead is used as a glaze. The celebrated Sevres porcelain is generally composed of China clay and of a decomposed felspar rock, resembling the clay of Cornwall and the Cornish stone. The proportions of materials employed at the manufactories of Sevres for ware which is to be glazed are thus given: Silica, 59; alumina, 35*2 ; potash, 2*2 ; lime, 3*3 parts. The glaze is made of solid felspar calcined, ground, and washed. The kaolin is washed at the pit from which it is obtained, and is sent in this condition to the factories of Sevres, where it is again carefully washed to free it from coarser particles, and finally passed through very fine sieves. To this pre- pared clay the ground felspar rock is added in certain pro- portions, and the mixture is then deprived of a chief part of its water, after which it is set aside for many months in damp cellars. When required for use it is first dried and pulverized, and then slightly moistened ; it is then placed on a floor and is trodden upon by a barefooted workman for a con- siderable time. This operation is found to increase the plasticity of the material. After this treatment it is moistened and formed into lumps, when it is ready for the potter's lathe. Being not so plastic as stoneware dough, it requires considerable care in handling, which is supposed to be one cause of the high price of porcelain as compared with stoneware pottery. The round plates and dishes are shaped on plaster moulds, but sometimes the paste is laid on as a crust, and at others it is turned into shape on the lathe. When a crust is 76 MECHANICAL INDUSTKIES EXPLAINED. to be made, a moistened sheepskin is spread on a marble table, and over this the dough is extended with a rolling- pin, supported on two guide-rules. The crust is then transferred over the plaster mould by lifting it upon the skin ; for it wants tenacity to bear raising by itself. When the piece is to be fashioned on the lathe, a lump of the dough is thrown on the centre of the horizontal wooden disc, and turned into form as directed in treating stone- ware, only it must be left much thicker than in its finished state. After it dries to a certain degree on the plaster mould, the workman replaces it on the lathe, by moisten- ing it on its base with a wet sponge, and finishes its form with an iron tool. A good workman at Sevres makes no more than from fifteen to twenty porcelain plates in a day, whereas an English potter with two boys makes from one thousand to one thousand two hundred plates of stoneware in the same time. The pieces which are not round are shaped in plaster moulds, and finished by hand. When the articles are very large, as washhand-basins, salads, etc., a flat cake is spread above a skin on the marble slab, which is then applied to the mould with the sponge, as for plates ; and they are finished by hand. " The projecting pieces, such as handles, beaks, spouts, and ornaments, are moulded and adjusted separately ; and are cemented to the bodies of chinaware with slip, or porcelain dough thinned with water. In fact, the mechani- cal processes with porcelain and the finer stoneware are substantially the same, only they require more time and greater nicety. The least defect in the fabrication, the smallest bit added, an unequal pressure, the cracks of the moulds, although well repaired, and seemingly effaced in the clay shape, reappear after it is baked. The articles RUSTIC FLOWER- VASES. 77 should be allowed to dry very slowly; if hurried but a little, they are liable to be spoiled. When quite dry they are taken to the kiln " (Ure). Tender porcelain, or soft chinaware of Sevres, is com- posed of a frit made of nitre, sea-salt, soda, alum, gypsum, and sand or ground flints. These are partially fused or fritted in a furnace, with constant stirring, so as to form a spongy mass. This is afterwards reduced to powder, and to each 3 parts of this frit 1 of the white marl of Argenteuil is added, and the whole well ground together and worked up into a paste with gum-water, which gives it sufficient plasticity to be handled. This tender paste can only be moulded in the first instance, as it will not bear turning in the lathe. The articles are first formed in moulds of plaster, much thicker than required to be when finished, and after being dried they are finished at the lathe with metal tools, after which they are baked ; but owing to the extreme softness which this porcelain acquires during the process of baking, saucers, plates, and similar articles require to be supported on earthen moulds. During the baking process their position is reversed, so as to prevent them from assuming an irregular form. In a work of this character it is impossible to enter more fully into the details of the manufacture, but it is hoped that the information given may prove sufficient to enable the reader to understand the principle upon which this important art is conducted. RUSTIC FLOWER-VASES. The following happy suggestion of the late Sir Joseph Paxton, whose name will ever be agreeably associated 78 MECHANICAL INDUSTRIES EXPLAINED. with the Great Exhibition of 1851, has been more or less adopted throughout the country, but not to an extent j which would have satisfied the eye of the gifted land- scape-gardener : "The introduction of vases even of a ! rustic character into cottage gardens will by many be | considered a startling proposition; but we can conceive nothing which would so alter the appearance of a cottage front, or that would tend to give so elevated a character and so attractive an appearance, as a rustic vase, ... if judi- || ciously filled with pelargoniums, fuchsias, or roses, in the j centre, and surrounded by plants of a drooping habit, | allowed to hang over the sides/' Now this idea suggests j to the mind a myriad ways in which rustic vases may i be fashioned at little cost by any one who has acquired the happy knack of handling ordinary carpenters' tools; and indeed we have frequently constructed such garden ornaments in the course of an hour or two, which were afterwards filled with good potting mould, over a layer of broken potsherds, and the vases furnished with plants appropriately grouped, presenting a very pleasing relief to other objects in the flower-garden. The following rough sketches will give an idea of the simplicity and ease with which rustic vases may be made by the amateur gardener. Fig. 1 represents a small butter-tub, perforated at its bottom by several holes, and secured to a forked branch of a tree, inserted so as to form a strong yet graceful support. The part of the branch upon which the tub rests is cut evenly, so that the vessel may stand perfectly upright, and this may be secured to the support by means of three 2-inch screws. In the first instance, it is well to fix the prongs of the branch, which should be of sufficient length for the RUSTIC FLOWER- VASES. 79 purpose, in the soil at the spot selected for its position. It should be sunk in the earth at least 18 inches, and with the aid of old bricks, or large stones, mixed with earth, it should be rammed down tight, so as to be firmly set. After this is done and the tub properly screwed to its place, pieces of " virgin cork " of nearly uniform length and width are placed round the tub, and fastened by ordinary cut nails. These pieces of cork must be allowed to project both above and beneath the vessel about 2 inches. In selecting the cork for this purpose but little Fig. 1. difficulty will be experienced in securing suitable pieces, and these may readily be cut, or, still better, broken off to the required size. Eigid uniformity should be avoided, for the vase will look better as a whole if the outer lining of cork presents a rugged and irregular appearance. In preparing these rustic vases for plants, a layer of broken fragments of flower-pots should first be spread over the bottom of the tub, then a layer of leaf-mould, and above this a compost made with good light soil, well-rotted 80 MECHANICAL INDUSTRIES EXPLAINED. vegetable matter, and silver sand, with the addition of a small quantity of loam. Plants that will not thrive in this compost ought to be ashamed of themselves. Fig. 2 is a shallow wooden box, perforated at the bottom for drainage, and attached to a tree stump, as before ; the sides of the box may be ornamented by short lengths of crooked wood cut from branches of an old tree. The required number of lengths may first be cut off, and these should afterwards be cut in half longitudinally, so that when the two halves are placed crosswise, they may nearly match in form. Fig. 3 represents what we may call a floral whatnot, and may be thus formed: A stout branch of a tree cut off transversely at its base is first driven into the ground as before. A moderate-sized tub is then selected, and a hole cut in the centre of the bottom sufficiently large to admit WATERPROOF CLOTH. 81 the branch, over which it is now slipped, and allowed to rest on the ground. A second and smaller tub is next to be screwed on to the flat face of the branch. A smaller branch is next selected and cut to a suitable length. Upon the lower end of this a piece of stout board is screwed or nailed, to act as a support, when this is placed upright in the second or middle tub. The upper end of this branch should be cut level, and another stout piece of board, cut into an octagon form, firmly nailed to it. If suitable lengths of virgin cork are now nailed round this, and secured by thin copper wire at the upper joints, a receptacle for an ordinary flower-pot will be at once formed. The drawing will give an idea as to the ornamen- tation of the tubs by means of cork. WATERPROOF OLOTH. There are many Avays of rendering cloth impervious to water while still allowing the air to pass through its pores. A solution of isinglass, alum, and soap has been success- fully used for this purpose. The solution is applied with a brush on the wrong side of the cloth while stretched on a board. When dry it is again brushed over on the w^rong side and against the grain of the cloth. The brush is afterwards dipped in clean water and passed lightly over tlie cloth, and the glossy appearance which the cloth thus assumes can be removed by brushing the cloth when dry. Solutions of indiarubber in turpentine, followed by coatings of a solution composed of sugar of lead, litharge, sulphate of zinc, with gum mastic and turpentine, have also been used for the purpose of rendering cloth imper- F 82 MECHANICAL INDUSTRIES EXPLAINED. vious to moisture. The surface thus prepared is after- wards covered with wool, or other material of which the fabric is made, cut into proper lengths and attached to the fabric by means of pressure, by which a pile or nap is formed. Cooley gives the following recipe for waterproofing, which appears to have the advantage of having been tried — with success : — " A simple method of rendering cloth waterproof, with- out being airproof, is to spread it on any smooth surface and to rub the wrong side with a lump of bees'-wax (per- fectly pure and free from grease) until it presents a slight, but even, white or greyish appearance ; a hot iron is then to be passed over it, and the cloth being brushed whilst warm the process is complete. When this operation has been skilfully performed a candle may be blown out through the cloth, if coarse, and yet a piece of the same placed across an inverted hat may have several glassfuls of water poured into the hollow formed by it, without any of the liquid passing through. Pressure or friction will alone make it do so. We have shown this to numerous cloth manufacturers, waterproofers, tailors, and others, several of whom have adopted the method very extensively, and with perfect success." PRUNING TREES AND SHRUBS. As a mechanical operation, the art of pruning requires both judgment and skill; and when we consider that the fruit-bearing power of trees and shrubs depends greatly upon the judicious application of the knife in due season and in a systematic manner, it will be conceded that the PRUNING TREES AND SHRUBS. 83 subject is worthy of special attention. Loudon thus gives directions for pruning from a scientific point of view which will be readily understood even by those who have not devoted much attention to the subject : " In the operation of pruning, the shoots are cut off close to the buds, or at a distance not greater than the diameter of the branch to be cut off; because without the near proximity of a bud, the wounds will not heal over. In shoots which produce their buds alternately, the cut is made at the back of the bud, sloping from it so that it may be readily covered by the bark in the same or in the following year ; but in the case of branches where the buds are produced opposite each other, either one bud must be sacrificed or the branch must be cut at right angles to its line of direction, which is most conveniently done with the pruning- - hears." The following practical instructions for pruning were given by the late Sir Joseph Paxton, and will be read with interest by all lovers of the orchard and its produce : — " The pruning of fruit-trees and bushes is sadly neglected in most cottage-gardens, the trees often presenting a com- plete wilderness of crowded branches, producing in some seasons great numbers of small, worthless fruit, and in others failing entirely; besides, by their impenetrable shade, permitting nothing to grow beneath them. One great cause of these evils is want of pruning; therefore, those who do not understand the principle of pruning will do well to thin out yearly, at this season (autumn), the weak spray wood, and removing all branches that cross each other, leaving the trees and bushes regular and uniform, and keeping them open in the centre ; for although they do not cut so judiciously as a practised gardener would, 84 MECHANICAL INDUSTRIES EXPLAINED. they will find, nevertheless, that they have done a great deal of good, which will be apparent in the increased health and fruitfulness of their trees. After standards have become old, this thinning and regulating is all that is required; but pruning should be commenced in the early stage of a tree's growth, for if it becomes necessary to remove large branches the tree suffers by it, and it tells of previous bad management; therefore do not suffer any branches to remain in your young trees which you know it will be necessary to remove hereafter. In pruning dwarf standard apple-trees, cut back until sufficient shoots are produced to form main branches, which may be trained out to the proper form by placing two hoops of the desired width in the centre of the tree, training the young main branches over on their outside ; in the early career of the tree, these young vigorous shoots should not be much pruned back, but only their unripened points removed, always looking at the direction of the eye before the cut is made, as the form of the tree will depend upon this. If this is neglected, perhaps the shoot may grow sideways, or, what is worse, inwardly ; therefore always prune to a bud that points outwardly ; this should be attended to in every species of pruning. " When your trees have arrived at the desired height, nothing more will be required than to prune the top shoots close off every year, and the side ones to one or two eyes; by which means an abundance of fruit-spurs will soon be formed; and from trees kept thin in this manner the finest fruit is obtained, besides the great advantage of their occupying little room. Dwarf pears, of some of the best kinds, should also be procured to be trained like pyramids — that is, one straight stem PPtUNING TREES AND SHRUBS. 85 made to throw out numerous side branches up its whole length by yearly heading it back ; which side branches are tied down to each other, making them assume a pendent or weeping form ; by this means some of the choicer pears may be grown to great perfection without occupying much space. Pears do not become fruitful if severely pruned, which should, therefore, be confined to thinning out the young branches in July, leaving little to be done now, shortening only in cases wdiere a supply of young shoots is required; but the things on which fruitfulness most depends are their first planting, and after root-pruning when necessary. First, then, in planting, the roots must by no means be buried deeply, and in wet situations, or retentive clayey soils, they should be rather raised into a little mound above the surrounding surface ; the holes .should be dug wide, say 4 feet, and deep enough to admit being partly filled up with stones, brickbats, or some material that will prevent the roots penetrating deep into the subsoil and serve as drainage at the same time ; 2 feet will be sufficient depth of soil. This precaution will contribute to the health of the trees, bring them to a bearing state at a much earlier age, and materially improve the quality of the fruit. The strong tap-roots, if any, should be pruned off at the time of planting, and the others laid out carefully; if, after this, there may seem any disposition in the trees to grow too strong, the roots must be cut off with a sharp spade all round at about a yard from the stem ; and any established unfruitful trees may be treated in the same manner, which will cause them immediately to form fruit-buds : by this system a mass of healthy fibrous roots is produced near the stem, enabling you to dig and crop near the trees without injuring them ; 86 MECHANICAL INDUSTEIES EXPLAINED. and any mulching with dung, or watering when necessary, is sure to have the desired effect, from the certainty of the range of the roots. "It cannot be too strongly borne in mind in lifting trees, that it is the small roots which chiefly supply nourishment to the plant; too much care cannot, there- fore, be taken to preserve them from injury in the removal; and the little additional labour this may cost over removing them carefully, will probably be repaid by a crop of fruit a season earlier, or, at all events, by success in the operation. Unless the tree is too thick with wood, there is no necessity for removing branches on account of transplanting, or, at least, only as many as may seem equivalent to the loss of roots, which, with care, will be little or nothing. When the trees have begun to grow again, they may be regulated, by taking out, or shortening only, the weakest shoots. What is termed spur-pruning is the best system for outdoor grapes — that is, leaving only one or two eyes of the last year's wood on the main branches, and a few short rods, four or five eyes each, in situations where it may seem expedient to replace an old shoot, or cut one down at some future time, which should always be considered, as by this means your vine may be kept furnished with young, healthy, fruit- bearing branches, even where the space intended to be covered is considerable. The young wood at the end of the main stems should not be left too long, as some are apt to leave them, thinking to gain time ; or the consequence will be that the lower part, of the vine will become weakened, and its regularity destroyed by the upper eyes breaking strongly, and the lower ones feebly : endeavour rather to have a regular distribution of young wood by PRUNING TREES AND SHRUBS. 87 short rods throughout the tree without crowding, which is a great fault. "The neatest and best plan for training is to carry the main stem horizontally near the ground, into which it may be allowed to dip and root, if the distance it has to go is considerable, taking up from it, at regular intervals, perpendicular main branches. Some of the strongest, straightest, and best-ripened cuttings of goose- berries and currants may be planted, previously picking out all the eyes quite clean except three or four of the terminal ones ; they may be reduced to about a foot long ; by removing a portion of their unripened points, and by picking out the eyes, the bushes are prevented from throw- ing up suckers. Bushes with about 1 foot of stem look much better, besides, in some measure, assisting to prevent the fruit becoming dirted by heavy rains. Neither prune nor transplant during frosty weather ; dull, mild weather being the best." In pruning currant and gooseberry bushes, all branches which have good buds should be retained, as also all well- ripened shoots. Meagre and half-ripened shoots should be cut away to within an inch of the branch. All erect shoots must be removed except when required to fill up any space which may be bare of wood. Every awkward and thick shoot should be cut away close to the stem. The shoots should not be suffered to grow too close together, but each have ample room. When it is desired to provide a future stock of young bushes, the best and strongest shoots removed by the pruning-knife or shears should have all their lower buds stripped off, with the exception of four top buds, and the shoots may be at once stuck in the soil in a shady border. By the following 88 MECHANICAL INDUSTRIES EXPLAINED. autumn, if all goes well, the shoots will have well rooted, and have at least two good shoots at the top. These should be cut down so as to leave about four eyes or buds on each. jj It is commonly the practice, in pruning roses, to per- j] form the operation at two different intervals — the first i cutting being made at any favourable opportunity between December and February, and a final cutting after the I spring growth has vigorously set in. Bearing in mind | that the flowering buds make their appearance only on | the vigorous young wood, the pruning should be so man- ji aged as to leave only one or two good buds at the base of | each healthy shoot. All old and sickly wood should be cleared away. COTTON WADDING. This well-known and useful material is made by attach- ing carded cotton to tissue paper previously coated with size, which is prepared by boiling the cuttings of hare-skins and adding a small quantity of alum to the solution. The sheets of wadding sold at the shops consist of two sheets, prepared as above, placed face to face, by which a very soft wadding is formed of good thickness, but of exceeding lightness. When these sheets are separated, by being carefully pulled asunder, they form very useful coverings for plated or silver articles to prevent them from tarnishing when not in use. The other useful purposes to which wadding is applied are too well known to need recapitula- tion. MANUFACTURE OF BRASS. 89 MANUFACTURE OP BRASS. This important alloy of copper and zinc is largely manufactured in Birmingham and Berlin. A vast number of useful and ornamental articles are made from it, and in- deed from the great extent of its application, it may fairly be considered the most important alloy known to the arts. The brass of the ancients was an alloy of copper and tin, resembling the alloy now generally known as bronze. The alloying of copper with zinc appears to have been practised to some extent about fifty years before the Christian era, but it was not until some centuries after that its manu- facture became fully developed. Brass was formerly made by placing in a crucible granu- lated copper, called lean-shot, or copper clippings, with calcined native carbonate of zinc and charcoal, and exposing them to strong heat. This plan was afterwards superseded by plunging strips of copper into melted zinc. The copper readily unites with the molten metal, and fresh quantities are added until an alloy, not easily fused, is formed. This is afterwards broken up into fragments, and remelted under a layer of charcoal, with the addition of either metal to bring the alloy up to the colour and standard required. The alloy is then cast in granite moulds, which are preferred to those made from any other material. It is afterwards annealed, and when cold is passed through rollers, and thus converted into thin sheets of any desired gauge. Sometimes brass is made by pouring the two metals, zinc and copper, together when in a melted state, very quickly, and with vigorous stirring at the time. For making the best quality of brass, 2 parts of copper to 1 of zinc are employed; but the bright yellow brass 90 MECHANICAL INDUSTRIES EXPLAINED. formerly known as Prince's or Prince Eupert's metal consists of about 2 parts of zinc to 1 of copper. Fine malleable brass for sheets, tubes, etc., is made from various formula. I. Copper, 7 parts ; zinc, 3 parts. II. Fine copper, 4 parts; zinc, 1 part. III. Copper, 33 parts ; zinc, 25 parts. IV. Copper, 3 parts ; zinc, 2 parts. These are malleable whilst hot. Red brass contains only a small percentage of zinc, sometimes as little as 8 or 10 per cent. Brass for castings. — The alloy for fine brass is some- times used for superior castings, or either of the following : I. Copper, 62 parts ; zinc, 35 parts ; lead, 2 parts ; tin, 1 part. II. Copper, 60 ; zinc, 36 ; tin, 4 parts. These alloys are rather brittle, and of a palish colour. III. Copper, 90 parts ; zinc, 7 parts ; tin, 2 parts ; lead, 1 part. Crilding metal. — I. Copper, 64 parts ; zinc, 32 parts ; lead, 3 parts; tin, 1 part. II. Copper, 82; zinc, 18 ; lead, 1 ; and tin, 3 parts. Brass for turning. — I. Copper, 65 parts; zinc, 33 parts ; lead, 2 parts. 11. Fine brass, 98 ; lead, 2 parts, melted together. III. Copper, 61 ; zinc, 36 ; lead, 3 parts. Brass solder. — I. Brass, 3 parts ; zinc, 1 part. This is used for soldering tubes and joints, and for all purposes where great strength is required. II. Fine brass, 12 ; zinc, 6 ; tin, 1 part, united together by fusion. Brass for wire is made from copper, 72 parts, and zinc, 28 parts; or copper, 64, and zinc, 34 parts. In making wire from either of these alloys the metal is first annealed; and it is subjected to the same process fre- quently during the operation of drawing into wire. Button brass, or platin of the Birmingham manufac- turers, is composed of 8 parts of brass and 5 parts of zinc, MANUFACTURE OF BRASS. 91 while their cheaper button-metal is composed of copper, tin, zinc, and lead. Dutch metal, from which Dutch gold-leaf is made, is an alloy of copper, 11 parts ; zinc, 2 parts. Pinchbeck, similor, and Mannheim gold are names given to an alloy similar to Prince's metal (which see). When the alloy for malleable brass has been cast into plates, it is usual to cut these into ribbons of various breadths (commonly about 6^ inches). This is done by powerful machinery, and the ribbons are first passed through the cylinders of the rolling-press while cold ; but as the pressure of the rollers hardens the metal consider- ably it requires to be annealed in a furnace, after which, when cold, it is again passed through the rollers. The rough edges of the plates are then trimmed in a suitable machine, and now two plates are rolled at a time, the annealing process being occasionally repeated. When very thin sheets are required, sometimes as many as eight plates are passed through the rollers at one time. The annealing of the sheets in the furnace requires great care, and must be done with perfect uniformity, otherwise they will not roll out equally. The plates are placed one above another, with clippings of brass between each, so as to allow tlie heated air to pass between them. The anneal- ing-furnaces are commonly about 32 feet long by 6i feet wide. The sheets, which are sometimes 24 feet long, are placed in the furnace and removed together. For this purpose an iron carriage nearly as long as the furnace is employed. Upon this the sheets are laid, and the carriage is brought to the height of the furnace door by means of a crane. Two such carriages are used in order to avoid loss 92 MECHANICAL INDUSTRIES EXPLAINED. of furnace-heat ; one of these is employed to convey the sheets to the furnace, and the other from it. Dutch leaf, which is so extensively used as a substi- tute for leaf-gold for " gilding cheap picture-frames and other purposes, is made from very thin brass beaten out by a hammer worked by steam-power. The hammer gives from three hundred to four hundred strokes per minute. From forty to eighty leaves are laid over each other, by which means the metal acquires the required lustre. SOLDERING. The art of uniting two different metals, or parts of the same metal, so as to form a perfect union, requires both knowledge and skill for its perfect accomplishment. The solder " employed depends upon the nature of the metal or metals to be joined, and the subsequent usage to which the soldered article may be subject. Hard soldering, for brass tubings, and for uniting other brass surfaces, consists in first scraping or cleaning the parts to be united, and then applying, with a camel- hair brush, a thick paste made with powdered borax and water, or by rubbing a lump of this substance upon a piece of slate, moistened with water: the creamy condition which the borax assumes when thus rubbed up renders it very easy to apply to small surfaces. The solder (see p. 93) is obtained in the form of small grains, and these are spread thinly upon the part to be joined, after which the object is submitted to a full red-heat, when the solder "runs" into the intermediate space, forming a perfect junction. The moment the solder has fairly run the article is removed from the fire. In Irazing, as this SOLDERING. 93 process is called, sometimes it is necessary to employ solder which melts at a lower temperature than the ordinary " hard solder;'' in this case a larger amount of zinc is added, with also a little tin. Hard soldering is also applied to gold and silver, but in these cases silver solder and gold solder are used respec- tively. The former is composed of silver, 2 parts, and brass, 1 part, melted together and rolled or hammered out into thin plates, which are afterwards scraped clean and cut into small fragments for use. Borax paste is applied to the surface to be united, and small pieces of the solder laid upon the spot. A gentle heat is first given with the blow-pipe, to expel the water from the borax, after which the heat is raised to a cherry redness until the solder runs, when the blow-pipe flame is promptly withdrawn. Gold solder varies according to the standard or quality of the gold of which the article is made; the solder is composed of gold, silver, and copper in varied proportions:* that used for soldering 22-carat gold consists of gold, 18 dwt. 8 grains ; silver, IG grains; and copper, 1 dwt. The silver and copper are first melted together, with the aid of a little borax as a flux, after which the gold is added. Coppersmiths' solder is composed of 8 parts of brass and 1 part of zinc, the latter being added to the former wlien in a melted state. The alloy is afterwards granulated by being poured into water, upon the surface of which short twigs or pieces of straw are allowed to float to assist the separation of the metal into granules. Tin-plate, or vessels made from sheet tin, are soldered with an alloy consisting of tin, 2 parts; lead, 1 part. * The alloys of gold, and the formuhii for the proper solder to be used for each, are given in "Scientific Industries," p. 37, etc. 94 MECHANICAL INDUSTRIES EXPLAINED. Pewter is soldered with a still more fusible alloy, formed by adding bismuth to the above in various proportions to suit the nature of the article to which it is applied. Soft soldering, as it is termed, consists in applying the alloy of tin and lead given above to articles made of tin, lead, zinc, and sometimes iron. In applying this solder to the two first-named metals, rosin and sal-ammoniac are employed to the parts to be soldered, to protect them from oxidation, and to assist the running of the solder. In solder- ing zinc, however, it is necessary to apply muriatic acid to the part, which may be done with a feather, and which, forming chloride of zinc, enables the solder at once to become alloyed with the metal, to which copper or other metal may be joined. When applying soft solder, or " pewter solder," as it is sometimes called, to iron the chloride of zinc is used ; and this is previously prepared by putting small strips of zinc in a vessel and pouring upon them a little muriatic acid. In the course of a few minutes the solution is ready for use, and may be applied to the parts to be soldered by' means of the feather end of a quill. Sheets of lead may be united, without the aid of solder, by what is called the autogenous process. It consists in fusing two surfaces of the metal together, after being scraped clean, by means of a jet of hydrogen gas, or this gas mixed with common air. This process is sometimes called " burn- ing " the joints, by mechanics who practise it. In lining wooden tanks with lead it is sometimes of great importance that no other metal should be in contact with the lead ; the above process is in this case admirably suited to make perfectly sound joints without the aid of solder in any form. BRICK-MAKING. 95 BRIOK-MAKING. Like all other arts practised by what is called " rule o' thumb," the art of brick-making varies considerably, not only in the process of manufacture — if such it may be called — but in the article produced. Indeed, while there are thousands of fairly good bricks annually made, there are hundreds of thousands produced which are all but worthless. There are two kinds of clay used in ordinary brick- making, one a stiff clay, which produces a hard, red brick, and the other a yellow, loamy earth, which makes a grey- coloured brick. In preparing the clay for brick-making it is usually dug up in the autumn, and is allowed to lie exposed to the action of the air during winter. It is frequently turned or worked about during this period with a spade. In the following spring the clay lumps are broken up and thrown into a pit, soaked with water, and left for several days. The clay is afterwards worked up, or tempered, by knead- ing in a horse-mill. The kneading of the clay, although a tedious process, is of considerable importance, and much of the success of brick-making depends upon the care with which this has been accomplished. London brickmakers add sifted cinder ashes, in the proportion of about one- third, to the clay. When the material is sufficiently kneaded it is taken to the bench by the moulder, who takes up a lump in both hands, which he throws into the mould, removing the superfluous material with a flat tool made for the purpose. The moulds for brick -making are made of wood, and are ordinarily 10 inches long, 5 inches wide, and 3 inches 96 MECHANICAL INDUSTRIES EXPLAINED. deep ; and tlie bricks, when dry, are about 9 inches long, 4| inches wide, and 2J inches deep. It is considered that a clever moulder can mould from 4000 to 5000 bricks in a day. The moulded bricks are taken, as fast as made, by a boy, who puts them on a receiving-board placed on a wheel- barrow, and they are then taken to a workman, who stacks them carefully in rows, from which they are trans- ferred, when suflEiciently dry, to the cla7np, or kiln, in which they are burned. The clamps are made of the new bricks themselves ; a foundation is first made with these, and the dried bricks are built up, layer after layer, till the required height is reached. A layer of coal-breeze about 2 or 3 inches thick is strewed between each layer of bricks. A perpendicular fireplace, about 3 feet high, is arranged at the western end of the clamp. The flues pass through the clamp, and are filled with wood, coals, and breeze. When the bricks are required to be burned quickly — that is, in about twenty or thirty days — the flues are placed about 6 feet apart, otherwise 9 feet is about the regular distance. The ordinary varieties of bricks are yellow marl hricks; red and gi^ey stocks; place-hricks ; clinkers and fire-hricks. The place-bricks and stocks are used in ordinary wall- making ; the yellow marls, being a very superior hard and well-burned brick, are chiefly used for the outside of dwelling-houses or other buildings. "Floating bricks," says Dr. Ure, "are a very ancient invention: they are so light as to swim in water; and Pliny tells us that they were made at Marseilles; at Colento, in Spain ; and at Pittane, in Asia. This invention, however, was completely lost until M. Fabbroni published a discovery of a method to imitate the floating bricks of the BKICK-MAKING. 97 ancients. According to Posidonius, these bricks are made of a kind of argillaceous earth, which was employed to clean silver plate. But as it could not be our tripoli, which is too heavy to float in water, M. Fabbroni tried several experiments with mineral agaric, guhr, lac-lunse, and fossil-meal, which last was found to be the very sub- stance of which he was in search. This earth is abundant in Tuscany, and is found near Casteldelpiano, in the territories of Sienna. According to the analysis of M. Fabbroni, it consists of 55 parts of siliceous earth, 15 of magnesia, 14 of water, 12 of alumina, 3 of lime, and 1 of iron. It exhales an argillaceous odour, and when sprinkled with water throws out a light whitish smoke. It is infus- ible in the fire ; and though it loses about an eighth part of its weight, its bulk is scarcely diminished. Bricks composed of this substance, either baked or unbaked, float in water ; and a twentieth part of clay may be added to their composition without taking away their property of swimming. These bricks resist water, unite perfectly with lime, are subject to no alteration from heat or cold, and the baked diff*er from tlie unbaked only in the sonor- ous quality which they have acquired from the fire. Their strength is little inferior to that of common bricks, but much greater in proportion to their weight ; for M. Fabbroni found that a floating brick measuring 7 inches in length, 4|- in breadth, and 1 inch 8 lines in thickness, weighed only 14| ounces ; whereas a common brick weighed 5 lbs. 6f ounces. The use of these 'bricks may be very important in the construction of powder magazines and reverberatory furnaces, as they are such bad conductors of heat that one end may be red-hot while the other is held in the hand. They may also be employed for buildings that require to be G 98 MECHANICAL INDUSTRIES EXPLAINED. light ; such as cooking-places in ships, and floating batteries, the parapets of which would be proof against red-hot bullets." Besides the ordinary bricks referred to, perfoi^ated Iricks, glazed hoicks, waterproof hrichSy and other ingenious modi- fications have from time to time been introduced, all more or less possessing some features of apparent advantage. Fire-bricks, which are much employed for lining furnaces, retort-stoves, and all fireplaces subjected to great heat, are made from a refractory clay found in the neighbourhood of Stourbridge in Staffordshire. Crucibles for melting metals are also made from the same material. EMERY-WHEELS. There is no tool of more general use in a Avorkshop or manufactory than a solid emery-wheel, and perhaps there is no tool so little understood. If we may judge by the manner in which these wheels are sometimes mounted and used in workshops, the popular idea would seem to be, not only among ordinary, but good mechanics, that anything would do for an emery-wheel, so long as it was made to revolve at a high rate of speed, and the wheel able to stand any amount of abuse ; to this fact is probably due many of the accidents from bursting of the wheels and other sources of annoyance and danger. While it may be true that an emery-wheel carelessly mounted and improperly used may be useful and lucrative to a certain extent, it is also true that if it were mounted in a proper manner, and used with the care and attention given to any other tool, it would be far more useful and profitable. The first requisite to the proper running of an emery- EMERY-WHEELS. wheel is the machine upon which it is mounted This should be proportioned in weight and stability to the size of the emery-wheel, and also to the weight of the articles to be "round, always remembering that if the machine is too sli-ht perfect work will be impossible, whereas there will be^no disadvantage in having the machine stronger or heavier than is necessary. The spindle should be large and well fitted to the bearings, which should be long and have no end play, otherwise the corners of the wheel may be knocked off; care must be taken that the faces of the flanc.es are at a right angle to the spindle. A little deviation wilUend to break the emery-wheel when the flanges are brought together. , i ^ Wheels have often been known to crack or break from this cause, and sometimes to fly in pieces as soon as started, the operator being at a loss to account for the breakage in any other manner than that the emery-wheel was bad A packin- of rubber cloth or thick paper should be inserted between the faces of the flanges and the wheel; this will tend to overcome any slight imperfection in the accuracy of the flanges, insure a better fit, and secure the wheel more firmly and with less pressure from the nut. When the emery-wheel is secured between the flanges, it should xMuperfectly true, and should also be well balanced. If an emery-wheel, after being mounted perfectly true, is found to be out of balance, it should be immediately con- demned or not used until it has been properly balanced; before condemning the wheel, however, it is well to see that the trouble does not lie in the spindle itself The emery-wheel should never fit too tightly on the spindle, because the latter may become heated and expand, causing the emery-wheel to burst. It is better to have the hole 100 MECHANICAL INDUSTRIES EXPLAINED. in the emery-wheel much larger than the spindle, and a packing inserted to reduce it to the proper size. This packing may be of soft metal melted and poured in, or a wooden socket secured by cement may be used. The practice of securing the emery-wheel to the spindle by means of a key is considered objectionable. While considering the subject of emery-wheels, our attention was lately called to a new emery-wheel introduced by the Standard Emery- Wheel Company, of Greek Street, London, and by the courtesy of the manager we were enabled to see the wheels in full operation, and also the process of manufacture, w^hich we may say is conducted with much ingenuity and care. The object of the company is to produce an emery-wheel which shall possess all the advantages of tenacity, quickness of cutting, and safety — that is, non-liability to crack or break ; and in fairness to the patentee, we may state that these important conditions have been amply fulfilled. The principle upon which a good emery- w^heel should be constructed may be gleaned from the following state- ment : " It is necessary for perfect efficiency that the wheel shall cut freely, and neither glaze on the surface nor unduly heat the work. The particles of emery themselves, being extremely hard, sharp, and angular^ are exactly suited for the duty required of them, as they cut cleanly without tearing or scraping (just as a sharply pointed steel tool will do more work with less loss of power by friction, and consequent heating, than will a tool with a blunt point); and further than this, the emery grains never become blunted, for as they wear away in use by minute angular fragments being broken off, a succession of sharp edges and points is constantly presented. It is, however. EMERY-WHEELS. 101 extremely difficult to obtain a cementing material wliich, while possessing sufficient cohesive strength and adhesion to the emery, shall neither offer such resistance as to cause undue heating, nor distribute itself in a skin or glaze over the emery particles, and thus impair their cutting power. To take an example : glue or gelatine has been used as a matrix, and in some respects it fulfils the required condi- tions. It is sufficiently strong, adheres well to the emery, and is not too hard ; but it has the fatal defect of clinging to and covering over the working faces of the emery grains instead of wearing away and keeping them clean. An emery-wheel made with glue or any kindred substance as a matrix would therefore be a glazing-wheel, and may be taken as an extreme type of several classes of wheels in which this has been the main defect. It is necessary, then, that the matrix when it wears away should leave the wheel in dust, and not continue to adhere to the surface after its duty has been performed. In avoiding this fault it is easy to fall into the opposite one of choosing a cementing material so hard and unyielding as to produce a large amount of heat in working, owing to tlie friction and use- less expenditiire of force occasioned by its too great resistance. Any matrix of a hard stony nature is subject to these objections, as well as that of brittleness, adverted to above in considering the question of safety; and sellers of emery- wheels of this kind have given indirect evidence of the fact by advocating Jower rates of speed than is advantageous to use Avith wheels free from such defects ; and also by advis- ing the free use of water in grinding as a palliative." It will thus be seen that an emery-wheel must be pre- pared with due regard to every detail necessary to render it not only effective as a grinding tool, but absolutely free 102 MECHANICAL INDUSTRIES EXPLAINED. from liability to Ireah The danger to workmen from this cause is considerable with an emery-wheel of a brittle nature ; and it must be gratifying to grinders to know that these important tools can now be obtained of such a char- acter as not to endanger their personal safety. In order to give additional security to their wheels, the Standard Emery- Wheel Company attach a pair of safety-plates, one on each side of the wheel, set perfectly parallel, and with central holes, of the proper diameter to fit the spindle, bored accurately at right angles to their faces, by which the wheel must be accurately centred, and truly square with the axis of rotation, while the body of the wheel itself can- not touch the spindle. In fact, the safety-plates, and not the emery-wheel, are attached to the spindle, by which means the possibility of the bursting of the wheel by heat- ing and expansion of the spindle is absolutely prevented. It must be understood that the safety-plates " referred to do not correspond to the side plates ordinarily applied to common emery-wheels. OASK-MAKING. There are many systems adopted for making casks, but the following will give the reader a general idea of the principle upon which these useful vessels are constructed by the aid of suitable machinery. A circular saw is fixed to a strong bench, with a slide-rest upon which each piece of wood intended to form a stave is fixed. The rest slides forward in a curved direction, aided by an adjustable guide^ which brings the timber against the edge of the circular saw, causing it to be cut in the curved form required for the edge of the stave. A machine with suitable cutters. fullers' earth. 103 attached to a standard, traverses round with their carrier upon a centre, by which the upper and lower edges of the cask are cut round and grooved for the purpose of forming a suitable bed for the head of the cask. An apparatus is then brought into use by which the staves are cut to uniform length, and bevelled at either end. Another machine is employed, in which the cask is made to revolve upon an axis, and a cutting tool passes over the exterior of the cask to give it a smooth surface. When the staves have been cut to proper length and form, they are then set round within a confining hoop at the bottom, and arranged in the form of a cask, after w^hich they are held together by means of hoops placed temporarily over them. The cask is then placed in a frame upon a platform and raised by a lever, so that one end of the cask may come in contact with a series of cutters in a lathe above, which, traversing the interior of the cask to the extent of about 3 inches, cuts a circular groove, called the chine, into which the head of the cask is afterwards fixed. The cask is now reversed, and the opposite end is grooved, or chined, in the same way. The heads of the cask are formed from pieces of wood, cut perfectly straight and laid side by side, after which they are cut to the required diameter by a revolving cutter. The cask is afterwards made up with hoops of various sizes, and the heads inserted, after w^hich the hoops are driven tight, and the cask is complete. PULLERS' EARTH. This peculiar clay, which occurs largely in some parts of Berkshire, Surrey, and other counties, is extensively 104 MECHANICAL INDUSTRIES EXPLAINED. used in the cleansing of woollen stuffs, in the manufacture of cloth, and for many other purposes. Its chief attribute IS Its power of absorbing greasy matter, which it does in a remarkable degree. There are two kinds of fullers' earth known m commerce, the blue and the yellow. The latter is employed in fulling the finer cloths, while the former IS used for the coarser fabrics. Fullers' earth is chiefly composed of silica and alumina, but it is to the latter substance that the earth owes its power to absorb greasy matters. ^ When the clay is removed from the pits, it is first baked, or dried in the sun, and then thrown into cold water, m which it falls into a fine powder. The finer particles are then separated from the coarser by washing (or elutriating, as it is termed in chemical operations). The clay is worked up into a thin paste with water in a large tub. Several such tubs are placed in a row, each of whi?h is connected with the next by means of a spout at the top. A continuous stream of water enters the first tub, and this, overflowing into the other tubs, carries over the' finer earth, which is allowed to subside, and is afterwards col- lected and dried. This is used for cleansing the finer qualities of cloth. The coarser earth, after being dried, is employed in fulling the coarser kinds of cloth. Fullers' earth is frequently employed as a healing medium for sores and excoriations, more especially fox infants suffering from the effects of careless and slovenly nursing. FILE-MAKING. 105 PILE-MAKING. There are two kinds of tool emj^loyed in the preliminary process of rendering metals, wood, horn, etc., smooth previous to polishing. These are the file and the rasp. The steel from wliich hies and rasps arc made must be of the finest quality of cast steel, but the best Lancasliire files are made from the best Swedish hoop iron. Files are either single or donhic cut, according to the purpose for wliich tliey are required. Tn the former, a series of sharp edges are cut diagonally across the surface of the steel by means of a sharp-edged cliisel. The double cut is given by cross-ciUting — that is, making a series of cuts at the same angle as the former equally across each cut. The single- cut iiles are chiellv u-cd for filing brass and copper, wliile the double-cut lilcs arc more suitable for steel, cast iron, and otlier liard metals. If a double- cut iile is used for a soft metal like copper, it is liabh^ to become clogged with this metal, and in a very slKiit time ceases to perform its proper function; and, on tiic other hand, a single-cut iile, if ai)plied to hard metals, as steel, for example, passes over the surface without (hung the w^ork required of it. Files are cut of various degrees of iineness, called re- spectively rough, bastard cut, second cut, fine cut, and smooth. The large heavy files used by smitlis are some- times even coarser than ordinary " rough " files, and these are called "rubbers." Files are also of various forms, as llat, half-round, three-square, four-sided, and round. Half- round and three-square files are generally tapering, except- ing when the latter are required for saw-sliarpening, when they arc of a prismatic form. 106 IMECHANICAL INDUSTRIES EXPLAINED. In forging the steel for file-making, it is first made red- hot upon a coke fire, after which it is hammered upon an anvil specially constructed for the purpose, on one end of which is a projection furnished with a hole to receive a tool for cutting the file lengths from the rod of steel. In the anvil there is a deep groove to hold the dies which give the required forms to the files. Flat files are made entirely by hammering. The hot steel bar is held by one workman, who strikes it with a small hammer, while another workman strikes it with a larger hammer. By the wonderful precision with which, by constant practice, this operation is conducted, the surface of the metal is rendered perfectly smooth and flat, a most important point in the art of forging the metal for files of this description. Half-round files acquire their form by being hammered into a boss or die, which is fastened into the groove in the anvil. The rod is laid on the boss and hammered until it fills the die. The three-sided files are also formed in a die, the recess being two sides of a triangle. The steel rod is first hammered square, and then one angle is placed in the die, and the hammer applied until the three sides are properly formed. In file-cutting, the chisels employed are somewhat broader than the file ; they are sharpened at an angle of about 20° ; and the length is such as to enable the file- cutter to hold them conveniently between his thumb and forefinger. The blow of the hammer is given with great pre- cision, and the chisel handled with considerable dexterity, so as to ensure regularity in the cuts with quickness of movement. The file is first laid upon the anvil, one end projecting over its front and the other over its back edge. It is next secured in its position by means of leather FILE-MAKING. 107 straps, which are furnished with stirrups, to enable the cutter to keep the file in its position by means of his feet. The file is first single cut on one side, and afterwards cross- cut as before mentioned. Before cutting the other side of the file a flat block of soft metal, composed of lead and tin, is placed on the anvil, upon which the file is laid with its cut face downward. The object of this is to prevent the cutting of the first operation from being obliterated by the hard surface of the anvil. When half- round or three-square files are being cut, they are placed in rounded or angular grooves in the soft metal. Rasps are cut with a triangular punch, which leaves projections all over the surface of the steel of a pyramidal form ; and the cuts are made with the utmost uniformity which an experienced workman can accomplish. Indeed the precision and neatness with which the art of file-cutting is practised is highly creditable to those who pursue it with such uniformly good results. Hardening the files is of the greatest importance, since it is upon this quality that the usefulness and dura- bility of the file mainly depend. If the file, after being cut, were to be made red-hot and thrown into water, in the same way that other steel tools are treated, the oxidation of the metal which accompanies this operation would aflfect the fine sharpness of the teeth and thereby impair the efficiency of the tool. To prevent the surface of the file from being acted upon by the oxygen of the air, after being made red-hot, it was formerly the custom to coat it first with ale-grounds, and then to cover it with powdered salt. When this coating was dry, the file was made red- hot, hardened, and then brushed over with coke-dust, which gave it a bright metallic lustre as if it had not 108 MECHANICAL INDUSTRIES EXPLAINED. been subjected to the fire. An improvement in this system was afterwards introduced, which consists in making a saturated solution of salt, to which ale-grounds are added, and this forms a creamy mixture which readily attaches to the steel. The files are first dipped in this compound, then made red-hot and hardened. In heating the file it is held by the tang in a pair of tongs, and placed in a forge fire, the fuel employed being small coke. The heating is done gradually, and as uniformly as possible; when of a cherry-red colour, it is quenched in very cold water. Some manufacturers employ sulphuric acid and water for hardening these tools, believing that this increases the hardness of the steel. In plunging the red-hot files into water it is usual to hold them perpendicularly, and to immerse them in the water as quickly as possible, so that the point shall not have time to cool before the stouter parts ; by this means warping is prevented. After the hardening is complete the files are brushed over with coke-dust and water, and finally well rinsed, dried, and rubbed over with a mixture of oil and turpentine. BRONZE. There is no alloy of metals, taken in its application to purely artistic purposes, which has held such an important position from remote ages up to our own time as that of copper and tin, known by the name of bronze. Although made from two such soft metals as those named, the alloy possesses great hardness, and was from this cause employed by the ancients for making swords, hatchets, and various tools, before the manufacture of iron was developed. About BRONZE. 109 seven hundred years before the Christian era, Tiieodorus and Esecus of Samos, according to Pliny, invented the art of modelling in bronze. It had long been known that an alloy of copper and tin was more fusible than copper alone, and that consequently the process of casting was easier, while at the same time an object produced from the alloy was considerably harder. During the reign of Alexander, the art of bronze-casting became greatly extended, and a celebrated artist, Lycippus, succeeded in multiplying groups of statues, by new processes, to such an extent that Pliny called them "the mob of Alexander/' After this colossal bronzes were produced, of which the isle of Ehodes possessed about a hundred, and the Eoman consul Mutanius discovered three thousand bronze statues at Athens, an equal number at PJiodes, Olympia, and Delphi, even after n large number had been removed from the latter city. The proportions in which copper and tin should be united to form a fusible alloy which will become hard on cooling, without being brittle, has often been the subject of great diversity of opinion. And indeed it is not only the proportion in which the respective metals are combined, but the method adopted in fusing them together that the art of making a good bronze consists. With the same weight of the two metals ]3laced in the hands of different metallurgists, it is more than probable that the resulting alloys would vary considerably. Indeed there are certain judges of " real bronze " who can distinguish at a glance the ancient from the modern bronze, be the latter never so cunningly disguised by artificial means. Modern bronze is generally made by alloying copper and tin with the addition of a moderate percentage of zinc, or zinc and lead. For bronze which has to be struck into 110 MECHANICAL INDUSTKIES EXPLAINED. medals, 92 parts of copper to 8 parts of tin, or 88 parts of copper to 12 parts of tin, are recommended as forming a tough alloy. A finer tint is given to this bronze by the addition of a small percentage of zinc. The bronze from which bells are cast, and which is known as bell-metal, is composed of 78 parts of copper and 22 parts of tin. This forms a very fusible alloy, and yields a rich sonorous tone on being struck by another piece of metal, hence its suit- ability in bell-founding. Chinese gongs are made from an alloy of copper and tin only, the gongs being hammered out until very thin. Cymbals are also made from the same alloy, but for these instruments a smaller percentage of tin is employed. The alloy from which cannons are made, and which is called gun-metal, consists of about 90 parts of copper to 10 of tin. The proportion of tin varies, however, according to the views of the respective founders. The antique bronze colour is given to modern bronze- work by applying certain substances which more or less affect the surface of the alloy, giving it the appearance of long exposure to the action of the air. The following recipes have been used for this purpose with good effect : 1. Sal-ammoniac, 1 drachm; salt of sorrel, | drachm; •dissolved in 14 ounces of white vinegar. Warm the bronze slightly, and apply with a camel-hair brush, repeating the operation until the desired tone is ob- tained. 2. Sal-ammoniac, 1 part ; cream of tartar, 3 parts ; common salt, 6 parts, dissolved in hot water, 12 parts; add to this solution of nitrate of copper 8 parts, and brush over the surface as before. After a while the bronze becomes covered with a green coat possessing great beauty. PLAYING CARDS. Ill PLAYING CARDS. As far back as the year 1832, 'Mv. De La Eue took out a patent for priutiiig playing cards in oil colours. In the old way of printing these cards, certain parts of the design upon the " picture " cards were produced by copper-plate printing, and the other colours were impressed in water colours by means of stencil plates. There is no doubt that ]\Ir. De La Lug's invention of printing in oil led to ]\Ir. Baxter s subsequent application of oil-printing, which in the present day has been extended to the production of oleographs and chromo-lithographs, many beautiful specimens of which now adorn the windows of the modern printseller. De La Lue's invention consisted first in printing the pips, and also the picture or court cards, in oil colours, by means of blocks or types; second, in effecting the same object in oil colours by means of litho- gi-aphy; and tliirdly, gilding or silvering borders or other parts of the characters by the printing process cither by types or blocks, or by lithography. The types or blocks are first used to print tlie ])ips repre- senting the various suits; or they are drawn upon stone in the usual way. The ink is applied to the blocks or stone in the same way that printers' ink is ordinarily applied, and the impression taken on thick drawing-paper by means of a press. The picture cards are produced from a series of blocks, each devoted to its own colour. When the required luimber of impressions of any given colour have been made, the second colour is printed on the surface, then the third, and so on. Each block is made to fit exactly in its proper place, so that the colours cannot interfere with each other during the process of printing. When lithography is 112 MECHANICAL INDUSTEIES EXPLAINED. employed in printing playing cards, it is necessary to have as many stones as there are colours used in the printing, and these must be applied with the same exactness as in type or block printing. The ornamentation on the backs of playing cards, which is sometimes exceedingly chaste and pretty, is produced 1 1 by a method similar to the above. IRONFOUNDING. The art of ironfounding includes many operations within its range, amongst which the most important are — remelting S the pig or other cast iron ; pattern-making ; making the ' moulds, and moulding, or casting. Melting the cast iron. — This is generally done in what is called a cupola furnace, capable of melting from ^ 3 to 5 tons of metal at a time. A blowing-machine is employed to assist the fusion of the metal. When the furnace is first lighted, a layer of wood is placed on the | bottom, and over this coke is piled, and the wood is then I liofhted ; in a short time after a blast of air is introduced, ; which hastens the kindling of the fuel. Before the blowing- machine is set going certain apertures in the sides of the i furnace are opened in succession, beginning at the lowest ; alternate charges of coke and pig-iron are now thrown into i the furnace, the iron having been previously broken up into small fragments of not more than about 14 lbs. ' weight each. The metal begins to melt in about twenty minutes after its introduction, and fresh charges are made about every ten minutes, each charge consisting of from 2 to 3 cwt. of iron. A cupola furnace will melt from 1 to 1| ton of iron per hour. It is reckoned that 200 lbs. IRONFOUNDING. 113 of coke will melt 1 ton of cast iron after the furnace has got up to its full heat. When the moulds for receiving the melted metal are formed upon the ground, these are generally placed a few yards from the furnace. When all is ready, a clay plug which stops up the lower opening of the furnace is pierced with an iron rod, and the molten metal then runs out into a gutter which conveys it to the mould ; and when this is full, the aperture of the furnace is again closed. When the moulds are very small, or at a considerable distance from the furnace, the melted metal is conveyed by iron pots or ladles lined with loam. These pots are carried by two or more men, according to their weight ; or sometimes they are conveyed from the furnace to the mould by means of a crane. When the iron has cooled in the mould it is taken asunder, and the superfluous metal is removed from the edges of the castings by means of a hammer, the edges being afterwards trimmed with a cold chisel. Moulds are made with loamy sand, or with a mixture of clay and sand worked up into a paste with water, and cow's hair added to keep the composition together. This mixture is made in a loam-mill worked by steam-power. Moulds are also made with what is called green sand — that is, sand as it comes from the pits — mixed with powdered coal, these being worked up together with a little water. Baked sand, or that which has been already used, is also employed for making moulds, and sometimes, for large pieces of work, all three of the moulding materials given are worked up together and give very good results. Moulding in green sand is carried on as follows : The pattern, which is generally made of wood or iron, is first H 114 MECHANICAL INDUSTRIES EXPLAINED. prepared. Two iron frames of exactly the same size are I used as a box or envelope for the moulds; the longest ! sides of these frames are united by parallel cross-bars about 6 or 8 inches apart. The two halves of the box have ears corresponding exactly with one another. One of these is pierced with holes, while the other has projec- tions which fit into them. This frame is of sufficient size to take the required pattern and the moulding material. When the mould has to be prepared, the two halves of the box are laid side by side on the foundry floor. Green sand is then shovelled into one of the halves until it is full; this is then gently beaten with a rammer. The pattern is now laid upon the level surface of sand, and sufficient pressure given to partially embed it in the sand. The second half of the box is then placed over the first, and this in its turn filled with the green sand, after which the box is reversed, by which the first half becomes uppermost. This is now removed with care and steadiness, and it takes with it the sand which had been pressed into it, but leaves the pattern embedded in the sand of the second half. The moulder now makes good any irregularities in the surface of the mould nearest the pattern, and sprinkles dry and finely-sifted sand over the exposed parts of the pattern. He next breaks up the bed of sand first formed in this frame, then covers the pattern with green sand, and replaces the frame in its former position, so as to re-form the box, and again fills the frame with sand, which he rams as before. The two halves of the box are now separated and the pattern carefully removed. But before the box is made up again it is necessary to form a series of channels in the sand for the passage of the melted metal, and CAMEL-HAIR PENCILS. 115 several smaller channels leading from the pattern for the escape of air. The box is now made up as before, and the ears secured together by bolts. The melted metal is poured into an orifice in the sand, called the gate. When the pattern is very large, several such apertures are made, and the metal is poured into each of these at the same time. Sometimes, before bringing the two halves of the mould together, it is the practice to dust over the two surfaces either with finely-powdered charcoal, contained in a muslin bag, or powdered plumbago. Moulding with baked sand, or that which has already been used, is conducted in the same way as above, and it is not usual to mix powdered coal with this sand. After the mould is finished, it is placed in a drying-stove, where it is allowed to remain until all the water employed in working up the sand is expelled, after which the mould is baked. Moulds thus prepared are more porous than those made from green sand, and consequently the air has better means of escape, which is very important when large cast- ings are required. Moulding in loam is performed by making the design in the moulding material from drawings previously prepared, instead of mouldiug from a pattern. CAMEL-HAIR PENCILS. The so-called camel-hair pencil, or brush, is more fre- quently made with the hair of any other animal than that of the hump-backed denizen of the desert, — the hair of the marten, civet, polecat, and even that of the domesti- cated mouser, being employed in the fabrication of these useful artists* tools. 116 MECHANICAL INDUSTRIES EXPLAINED. The hairs are generally taken from the tail of the animal, and this is first well cleaned by being scoured with a solution of alum, after which it is soaked in warm water for many hours. The tail is then passed through the hand from the base to the tip, so as to free it as far as pos- sible from the water and to lay the hairs down smoothly, after which it is dried with a cloth, and the hairs cut off in clumps close to the skin. These are afterwards set out according to their lengths, and the little bundles are next placed upright in tin pans, with the tips upward, and by a gentle tap upon the tin the hairs become arranged according to their respective lengths. The longer hairs are then separated from the shorter ones, by which means the equal length of the hairs is secured, and upon which the perfection of the pencil depends. Although when spread out flat upon a level surface the hairs of a good pencil, or brush, are of perfectly even lengths, when the tip is moistened and formed into a point by the lips or otherwise, the pencil assumes a tapering form by reason of the outer hairs of the brush becoming bent, or curved, at their points toward the centre hairs, which remain erect. After the bundles of hair have been levelled as described, a small pinch sufficient to make a brush is taken, and the lower end is tied by a thin thread, after which it is neatly bound by thin silk or thread up to a certain height. The next operation is to select quills of various sizes. These quills are obtained from geese, swans, pigeons, larks, and other small birds, according to the required size of the pencil. These are first cut to the proper length, and then soaked in water for many hours to prevent them from splitting. The brush of hair is then pointed and passed through the wider end of the quill, and is next WHITEWASHING. 117 gently pressed through the narro'v opening by means of a wire. When the softened quill becomes dry it naturally contracts, and thus firmly grips the bundle of hairs en- closed by it. Instead of employing quills in the manufacture of artists' pencils, it is now commonly the practice to insert the bundles of hair in metallic tubes appropriately tapered, and these are fixed into cedar or other wooden handles, thus forming an exceedingly agreeable tool to work with, and rendering the employment of quill-splitting handles unnecessary except in some instances. WHITEWASHINa. Custom has made us acquainted with the effect, if not with the method, of whitewashing. In preparing his whitewash " the workman puts a few lumps of whiting into a bucket, and works it up into a thin creamy mass with the addition of water, taking care to leave no lumps in th" mixture. Tu tliis is added a moderate amount of size, or thin glue, wliicli is well stirred in and thoroughly incorporated. It is api)lied to ceilings and walls by means of a broad, Hat brusli, wliich should be worked uniformly in one direction. Surfaces that liave been previously whitewashed should be first brushed over with a dry brush to remove dust, and aftpllorous, 175 Animalculce, 130 Annealed, 53 Annealing furnace, 91 glass, 22 Antique bronze, 110 Anvil, 106 Acpia regia, 73 A(piafortis, 187 A(iuatint, 128 Argcnteuil marl, 77 Argillaceous earth, 97 Arsenic, 29 Artificial glass, 75 ,, stones, 122 Artists' tools, 115 Asphaltum, 28, 124 Assaying, 182 Autogenous process, 94 Autographic ink, 135 Autography, 134 Balloons, 44 ,, air, 46 ,, lire, 46 safety, 45 Balsam of sulphur, 73 Bastard-cut tile, 105 Batch, 47 Beak-irons, 37 Bean-shot, 89 Bees'-wax, 82, 128 Bell-founding, 110 Binding, boards, 64 ,, cloth, 64 full, 64 half, 64 ,, Indiarubber, 64 ,, wire, 16 Binoxide of mercury, 60 Bird cages, 34 Biscuit, 68 kiln, 70 ,, ware, 70 Biting fluid, 126 „ in, 126 Black, Brunswick, 126 crayons, 41 ,, lustre, 152 ,, marble, 136 ,, on the grain, 180 ,, Wedgewood, 74 Blacklead pencils, 137 Block-printing, 168 ,, tin, 42 Bloodstone burnisher, 166 Blowing machine, 112 Blowpipe, 93 N 194 INDEX. Blue fullers' earth, 104 Boards, 64 Bobs, 151 Bo oj- wood, 1 Bolts, 52 Bookbinding, 63 Boss, 106 Bosses, 37 Bourgeois, 144 Boxes, snuff, 3 Boxwood, 5 Boxwood sawdust, 59 Bradawl, 4 Bran, 48 Brass, button, 90 ,, clippings, 91 cylinder, 64 finishing, 156 for castings, 90 ,, for turning, 90 ,j for wire, 90 ,, malleable, 90 manufacture of, 89 polisher (wall-papers), 169 ,, polishing and finishing, 153 ,, red, 90 ,, solder, 90 ,, stamps, 56 Brazing, 92 Bread, fancy, 49 ,, French, 49 ,, household, 47 ,, making, 46 seconds, 47 ,, unfermented, 50 ,, wheaten, 47 white, 47 ,, wholemeal, 48 Brevier, 144 Brick-making, 95 Bricks, fire, 96, 98 ,, floating, 96 glazed, 98 , , grey coloured, 95 kiln, 96 perforated, 98 ,, place, 96 „ red, 95 ,, stock, 96 ,, waterproof, 98 yellow marl, 96 Bright fine gold, 185 lustre, 61 Brilliants, 120 Brimstone match, 171 Bronze, 89, 108 ,, antique, 109 ,, casting, 18, 109 colossal, 109 Dutch gold, 162 gold, 162, 163 ,, modern, 109 ,, powders, 163 ,, real, 18 ,, silver, 163 ,, smoked, 22 Brooch, view, 3, 7 Brooches, 184 ,, bog-oak, 3, 7 Brown crayons, 41 Brummagem jeweller}^, 189 Brunswick black, 126 Brushes, camel-hair, 115 Buckets, 52 Buckskin gloves, 60 Buff, 153 ,, leather, 153 „ stick, 130, 153 Bull-neck leather, 151 Bung, 70 Burgundy pitch, 125 Burning (soldering), 94 Burnished gilding, 56 Burnisher, agate, 56 ,, dog's tooth, 56 steel, 166, 168 ,, bloodstone, 166 Burnishing, 163 ,, finishing, 165 ,, grounding, 165 Button brass, 90 ,, making, 148 Buttons, mother-o'-pearl, 149 ,, pewter, 149 Cabinet v^^obk, 122 Calcined redlead, 55 Calf-skin vellum, 53 Camel-hair brushes, 115 pencils, 115 Caoutchouc, 28 Capitals, 144 INDEX. 195 Car, 46 Carded cotton, 88 Cards, court, 111 ,, picture. 111 ,, playing. 111 Carrara diamonds, 136 ,, marble, 136 Carving Irish bog-oak, 1 Case-hardening, 17 Cask-making, ^102 Cast steel, 34 Casting, 68 Castings, brass, 90 Cedar wood, 138 Cements, 24 Dihl waterproof, 26 engineers', 26 ,, Hrejjroof, 26 ,, hydraulic, 24 „ Portland, 25 ,, Roman, 24 ,, steam-boiler, 26 stick, 119 stone, 24 Cementation, 17 Cements and mortars, 24 Centre pieces, 33 Ceramic art, 65 Chains, 52 Chairi, 21 Chalklime, 24 Chamois leather, 59, 1 53 Champagne l)ottles, 23 Charcoal, 17 ,, stove, 59 Chasing gold, 185 Chimney-stack, 62 China clay, 40, 74 ,, Dresden, 69 ,, English, 74 Chine, 103 Chinese gongs, 110 Chisel, 4 Chloride of gold, 73 ,, ,, zinc, 94 Chromolithographs, 111 Chuck, 32 Circular brushes, 151 saw, 102 Circ jKrdu, 20 Cisterns, 52 Clamp, 96 Clay, China, 74 Cleaning, leather, 179 Clinkers, 96 Cloth binding, 64 Collet, 120 Colossal bronzes, 109 Coloured chalks, 40 Colouring, 152 ,, jewellery, 185 Common steel, 34 Compo', 26 Compost, 79 Concrete, 25 Conducting rod, 62 ! Congreve light, 172 j Copal, 28 I Copper, granulated, 8:' ,, oxide of, 22 ,, rod, 62 Coppersmiths' solder, 1>3 Core, 20 Cornish stone, 69 Corrugated sheet-iron, 52 Cotton, carded, 88 Court cards, 111 Cowhide, 151 Crayon drawing, 131 Crayons, 40 ,, black, 41 ,, brown, 41 lithographic, 132 red, 41 ,, yellow, 41 Crocus, 17 ,, powder, 157 Cross-cutting files, 105 ,, hatching, 21 ,, riffled, 22 Crucibles, 23 Crystal glass, 177 Crystalline tin, 43 Culasse, 121 Cullenders, 30 Cupola furnace, 112 Currants, 87 Currying, leather, 178 Cushion, 55 Cutlery, 34 grinding and polishing, 38 196 INDEX. Cutting-press, 65 Cymbals, 110 Date-mark, 191 Dead lustre, 61 ,, or moulu, 58 Diamond type, 144 ,, powder, 119 ,, rose, 120 ,, rough, 119 table, 120 Dihl waterproof cement, 26 Distemper colour, 168 Dog-legged tool, 4 Dog's tooth burnisher, 56 Doily, 152 Double-cut files, 105 Dough, 47, 66 Dragon's blood, 123 Draw-bench, 141 ,, plate, 140 ,, tongs, 140 Dresden China, 69 Dressing, leather, 179 machine, 50 Drill, 160 ,, stock, 4 Driving cord, 67 Drum-head, 169 Dry colouring, 185 Dubbin, 180 Dutch gold bronze, 162 „ leaf, 92, 162 ,, metal, 91 Duty mark, 191 Dwarf pears, 84 Earring saw, 161 Earthenware, 65 Ebony, 2 Edge-tools, 34 Elastic varnish, 46 Electric fluid, 62 Electroplate, 130 Elgin marble, 136 Elutriating, 104 Emeralds, 182 Emery-cloth, 5 „ cloth, 158 grains, 100 „ wheels, 35, 98 Engineers' cement, 26 English china, 74 ,, matches, 174 Essence of turpentine, 55 Etching, 124 ,, Florentine, 125 ,, ground, 124 ,, needle, 126 „ on glass, 27, 129 Facets, 119 Fancy bread, 49 Fast pulley, 154 Felspar, 69 Fenders, 38 Fermentation, 47 Ferrocyanide of potassium, Figures, 144 Filagree jewellery, 184 ,, work, 185 File, 4 ,, bastard- cut, 105 ,, cross-cutting, 105 ,, doubie-cut, 105 ,, fine-cut, 105 „ flat, 105 ,, four-sided, 105 ,, half-round, 105 ,, making, 105 ,, rough-cut, 105 ,, round, 105 ,, second-cut, 105 ,, single- cut, 105 ,, smooth-cut, 105 ,, three-square, 105 Filter-stuff, 31 Fine (bright) gold, 187 ,, cut file, 105 „ gold, 185 ,, malleable brass, 90 Finials, 34 Finishing, 152 ,, brass, 153 Fire balloons, 46 „ bricks, 96, 98 „ clay, 22 Fireproof cement, 26 Flake-bran, 50 Flask, 19, 183 Flat file, 105 Flint glass, 176 ,, powder, 65 INDEX. 197 Flint steel and tinder box, 171 Floating bricks, 96 Flock-chest, 170 ,, dust, 171 ,, papers, 170 powder, 171 printing, 170 Floral whatnot, 80 Florentine etching, 125 Flower-vases, rustic, 77 Fluoric acid, 27 Fluor-spar, 129 Flux, 53 Fly-studs, 15 ,, wheel, 66 Forging, 35, 36 Forks, 35 Fossil-meal, 97 Fount of type, 144 Four-sided file, 105 French bread, 40 ,, clocks, 57 polish, 123 ,, polishing, 122 Fritted, G9 Fuchsias, 78 Full bound, 64 Fullers' earth, 103 ,, ,, blue, 104 yellow, 104 Furnace, 17 annealing, 91 ,, muffle, 73 Galvanizkd iiiox, 51 Gamboge, 123 Gas-fixtures, 34 Gasoline, 34 Gems, Oriental, 119 Gilders' wax, 58 Gilding, burnished, 56 ,, ' leaf, 56 ,, mercurial, 58 metal, 58, 90 oil, 55 ,, picture-frames, 55 red, 62 ,, stone, 60 ,, tools, 64 ,, wash, 58 with gold-leaf, 55 Gilt lettering, 56 Girdle, 120 Glass, artificial, 75 ,, crystal, 176 ,, cutting 176 flint, 176 ,, grinding, 177 ,, paper, 4 ,, tears, 27 Glasscutters' sand, 155 ,, wlieel, 177 Glasses, spectacle, 178 Glaze -cream, 70 ,, kiln, 70 ,, liquor, 73 Glazed bricks, 98 Glazing, 39, 69 wheel, 101 Cold, 130 ,, beating, 52 ,, bronze, 163 ,, chasing, 185 ,, colour, 55 ,, fine, 187 ,, ,, bright, 185 ,, jewellers', 186 ,, leaf, 55, 163 ,, lustre, 73 ,, ]dating, 188 ,, jmre, 182 ,, shells, 162 ,, size, 56 ,, solder, 93, 186 Gooseberries, pruning, 87 Gores (balloons), 46 Gossamer work, 185 Gouge, 4 Grain tin, 42 Granite moulds, 89 Granulated copper, 89 Grapes, pruning, 86 Graver, 4 ,, lozenge, 4 Gravers, 28 Grease-pot (tinning), 42 Green marble, 136 ,, sand, 113 Grey-coloured bricks, 95 Grinding and polishing cutlery, 38 ,, mills, 38 ,, wheels, 38 198 INDEX. Grindstone, 38 Groovini^, 146 Guhr, 97 Guide (emery wheels), 102 Gum, benzoin, 126 ,, elemi, 122 sandarac, 122 Gutta-percha, 28 Gutter-pipes, 52 Half-bound, 64 ,, round files, 106 Hall-mark, 191 Hand-finishing, 152 Hard soldering, 92 Hardening, 35 files, 107 Hare-skins, 88 Head flattener, 146 Hemp, 26 Hoop, 103 ,, iron, 105 Household bread, 47 Hydraulic mortar or Roman cement, 24 Hydrochloric acid, 51 Hydrofluoric acid, 129 Hydrogen gas, 94 Illuminating, 162 Indian ink, 134 Indiarubber binding, 64 ,, solution, 46, 81 Ingots, 30, 53 Ink, autographic, 135 Indian, 134 ,, lithographic, 133 Iodide of iron, 128 Iodine, 129 Iron galvanized, 51 ,, tools, 17 Ironfounding, 112 Ironstone ware, 71 Jewellers' gold, 186 rouge, 130, 152 Jewellery, 182 Kaolin, 74 Kiln, brick, 96 „ glaze, 70 Kneading-trough, 47 Knives, paper, 3 LAC-LUNiE, 97 Lamp chimneys, 23 Lamps, 34 Lanterns, 34 Lapidary, the art of, 118 Lathe, 6 ,, (metal spinning), 32 ,, polishing, 150 ,, potters', 67 Lead, 29 ,, glaze, 65, 69 ,, shot, manufacture of, 29 Leaden rubber, 137 Leaf -gilding, 56 ,, gold, 53 ,, mould, 79 Leather- currying, 178 ,, dressers' knives, 179 ,, dressing, 179 ,, patent, 181 Leaven, 50 Lenses, optical, 177 Letter-cutting, 142 Lightning conductors, 62 ,, rods, 34 Lime bob, 157 ,, finishing, 156 Limestone, 24, 130 Lime- wash, 118 ,, washing, 117 Linseed oil, 46 Liquation, 60 List-pot (tinning), 42 Litharge, 26 Lithographic crayons, 132 ink, 133 ,, paper, 135 Lithography, 111, 130 Loam, 80 „ mill, 113 Logwood, 11 Longprimer, 144 Loose pulley, 154 Lozenge graver, 4 Lucifer match, 171 Mace, 179 Magnesia, 24 INDEX. 199 i\Iahogany, 122 Making small tools, 158 Mallet, 179 Manganese, 25 Mannheim gold, 91 Manufacture of brass, 89 „ of lead shot, 29 of needles, 144 of pottery and porce- i lain, 64 ,, of tin-plate, 42 Marble, black, 136 „ Carrara, 136 ,, cutting, 136 Elgin, 136 ,, green, 136 Parian, 136 Pentelic, 136 ,, white, 136 Mar mo Greco, 136 ,, statuariOi 136 Matches, 171 ,, brimstone, 171 Congreve, 172 English, 174 . lucifer, 171 safety, 175 silent, 175 wax, 176 Matrix, 101, 113 ^lelting cast-iron, 112 ^lercurial gildinir, 58 Metal, Dutch, 91 „ gilding, 90 ,, i)ulishing, 150 ,, S2)inning, 3'J Metallic lustres, 73 „ rod, 62 tubes, 117 .Minion type, 144 ^lodern bronze, 109 Moiree metallique, 43 ]\Iop, 152 Mortars and cements, 24 jMother-o'-pearl buttons, 149 .Mould, 19, 53 Moulding, 113 sand, 19, 113 Moulds, 113 granite, 89 MulHe furnace, 73 Muffle kiln, 73 Muller, 56 Needle-polishing, 147 Netting, 46 Nitrate of soda, 22 Nitric -acid test, 187 Nitrous acid, 127 Nonpareil type, 144 Oak, Irish bog, 1 Oil of amber, 72 ,, gilding, 55 Oilstone, 4 Oleographs, 111 Oolites, 25 Opals, 182 Optical lenses, 177 Or inoulu, 57 dead, 58 ,, ,, red, 57 ,, ,, yellow, 58 Oriental gems, 119 Ox-gut, 54 Oxide of copper, 22 Packing, needle-making, 148 Palette-knife, 56 Paper-knives, 3 ,, lithographic, 135 ,, transfer, 135 Papier-mache, 50 Parallin, 125 Paratonnerre, 02 Parian marble, 136 Paste, 47, 122 Pasteboard, 63 Patent Hour, 50 ,, leather, 181 Pavilions, 121 Pelargoniums, 78 Pencils, black lead, 137 ,, camel-hair, 115 Penknives, 36 Pentelic marble, 136 Perforated bricks, 98 Pestle and mortar, 56 Pewter, 94 ,, buttons, 149 „ solder, 94, 191 Pica, 144 200 INDEX. Pickle, 51 „ bath, 51 ,, sulphuric acid, 141 Picture-cards, 111 ,, frames, 55 Piercer, 146 Pigs, 30 Pinchbeck, 91 Pipe-clay, 26, 40 ,, ware, 71 Pitch, Burgundy, 125 ,, mould, 178 Place-bricks, 96 Planishing, 188 Plaster of Paris, 48, 68 Plate-powders, 153 Plated ware, 34 work, jewellery, 188 Platin, 90 Platinum, 62 ,, lustre, 73 ,, wire, 141 Playing cards. 111 Pliers, 4 Plumbago, 31, 137 Points, 144 Polish, French, 123 Polishing and grinding cutlery, 38 ,, brass, 153 ,, French, 122 lathe, 150, 153 marble, 136 silver surfaces, 150 steel, 157 ,, zinc, 158 Pommel, 180 Porcelain, 74 clay, 26, 74 Sevres, 75 ,, tender, 77 Porphyry slab, 72, 139 Portland cement, 25 Posters, 144 Potash, prussiate of, 18 Potassium, ferrocyanide of, 17 Potters' lathe, 66 Pottery, stoneware, 75 ,, unglazed, 74 ,, ware, 65 Powder, diamond, 120 Press, 63 Prince Rupert's drops, 27 ,, ,, metal, 90 Printing body, 69 , , under the stoneware glaze, 72 Process, autogenous, 94 Proof-leaf, 72 Protoxide of iron, 25 Pruning, grape-vine, 86 ,, root, 85 ,, shears, 83 ,, spur, 86 ,, trees and shrubs, 82 Prussiate of potash, 18 Pulley, 67 ,, loose, 154 Pulp, 50 Punch, 143 ,, making, 160 Pure gold, 182 Pyramids, 84 Pyrometric balls, 70 Quicklime, 24, 117, 156 Quicksilver, 58 Quills, 116 Rasp, 7, 105 Rasping, 50 Rasps, 107 Razors, 34, 36 Real bronze, 18, 109 Red crayons, 40 ,, brass, 90 ,, bricks, 95 ,, gilding, 62 „ lead, 26 ,, or moulu, 57 Refractory clay, 98 Revolving cutter, 103 River sand, 26 Rock crystal, 136 Rolling-press, 91 Rolls, 49 Roman cement or hydraulic mor- tar, 24 Root pruning, 85 Rose diamonds, 120 Roses, pruning, 88 Rosewood, 122 Rotten-stone, 129 INDEX. Kou_,e-paste, 152 Rough diamond, 119 „ cut file, 105 sandinc:, 156 Round file, 105 Rubber, 123, 144 cloth, 99 Rubbers, 105 Rustic flower- vases, 77 Safety balloon, 45 matches, 175 Saggers, 70 Salvers, 163 Sand, moulding, 19 Sanding, 156 Saw, tenon, 3 Saws, 38 Scale, 51 Scissors, 34, 37 Scraper, 158 Scrollwork, 11 Sculpter, 4 Scythes, 34 Second-cut file, 105 Seconds bread, 47 Sevres porcelain, 75 Shamrock studs, 13 Shear steel, 34 Shearing machine, 170 Shears, 34 ,, pruning, 83 Sheet iron, 42, 51 „ met^il, 32 tin, 42, 93 ShelHeld lime, 156 Shellac, 16, 123 Sh.'lls, gold, 162 silver, 163 Shot tower, 29 Shrubs, pruning, 82 Signatures, 63 Silent matches, 175 Silica, 24, 104 Silver, 130 bronze, 163 lustre, 73 ,, sand, 80 shells, 163 ,, solder, 93, 186 Similor, 91 Single-cut file, 105 Size, 117 Skin-finish, 21 Slicker (tool), 180 Slide-rest, 102 Slip, 68 Small chisels, 159 „ drills, 160 „ pica, 144 ,, punches, 160 „ steel burnishers, 162 Smoked bronze, 22 Smooth-cut file, 105 Snake, 131 Snutf-boxes, 3 Soda, nitrate, of, 22 Soft soldering, 94 Solder, brass, 90 ,, coppersmiths', 93 ,, gold, 93, 186 ,, pewter, 94, 191 silver, 93, 190 Soldering, 92 ,, hard, 92 soft, 94 Solution of Indiarubber, 81 Sorting, needle-making, 148 Spectacle glasses, 178 Spice-canisters, 34 Spindle, 66 Spinning, metal, 32 ,, zinc, 34 Spire ornaments, 34 Spirit of tar, 73 ,, varnish, 56 Sprinkling, 63 Spun-metal, 34 Spur-pruning, 86 Stamping, 64 Stamp, acorn, 11 Standard gold, 62 mark, 191 Standards, 84 Statuette, 18 Staves, 102 Steam-boiler cement, 2G Steel burnisher, 165 ,, burnishing, 167 ,, cast, 34 common, 34 gouges, 160 202 INDEX. Steel polishing, 157 ,, shear, 34 Stencil plates, 111 Stencilling, 168 Stock bricks, 96 Stones, artificial, 122 Stoneware, 70 dough, 75 ,, pottery, 75 Stopping, etching, 128 Striker, 35 Struck work, jewellery, 190 Stud, fly, 15 ,, shamrock, 13 Stylus, 126 Suckers, 87 Sulphate of baryta, 72 Sulphuret of antimony, 172 Sulphuric acid, 51 Swage, 35 Swansdown, 152 Swimming-tub, 169 Table diamonds, 120 ,, knives, 34 Tap-root, 85 Tea-trays, 51 Tempering, 35, 146 Tender porcelain, 77 Tenon saw, 3 The art of lapidary, 118 Three-square file, 105 Throwing, 66 Thumb-piece, 145 Tin bath, 42 „ plate, 42, 93 Tinning, 42 Tissue paper, 46 Tool, veining, 15 Tow, 26 Transfer paper, 135 Transferring, 135 Transplanting, 86 Trees, pruning, 82 Trent sand, 155 Tripoli, 119, 129 Troughs, 38 Tubes, 52 Turmeric, 123 Turning, brass for, 90 „ lathe, 67 Turquoises, 182 Type-founding, 142 ,, metal, 142 Unfermented bread, 50 Unglazed pottery, 74 Valve rope, 45 Veining tools, 15 Venice turpentine, 133 Vert antique y 22 Vestas, 176 Vice, 140 View brooch, 3, 7 A^ine, pruning, 86 Virgin cork, 79 w^ax, 125 Vitriol, 64 Vulcanite, 148 Wadding, cotton, 88 Wall-papers, 168 Wash-gilding, 58 pot, tinning, 42 Watch-balls, 71 ,, cases, 184 ,, movements, 120 seals, 190 Watches, potter}^ 71 Water coolers, 34 ,, wheel, 38 Water-of-Ayr stone, 131, 1 Waterproof bricks, 98 „ cloth, 81 Wax, bees', 128 ^ ,, matches, 176 virgin, 124 Weather-vanes, 34 Wedding-rmgs, 182 Wedge wood ware, 74 Wet-colour jewellery, 185 Wheaten bread, 47 White bread, 47 „ lead, 26 marble, 136 Whitewash, 117 Whitewashing, 117 Whiting, 117 Wholemeal bread, 48 Wicker work, 46 Wire, binding, 16 INDEX. 203 AVire. brass, 90 drawinf% 140 Wood, box, 5 Yeast, 47 YpUow crayons, 41 ., fullers' earth, 104 Diarl bricks, 96 Yellow or moulu, 58 Zinc BATH, 51 ,, chloride of, 94 ,, polishing, 158 ,, spinning, 34 stamping, 34 Zincing- process, 52 4 yt. AND A. K. JOHNSTON, EDINBURGH AND LONDON. Nolo Ready, Crown 8vo, 204 pp. full bound, cloth, price 2s. Gd. post free. Scientific Industries Explained. Showing how most of the important Articles of Commerce are made- Vol. I. By ALEXANDER WATT, F.RS.S.A. PEEFACE. ^'Knowledge is Power. ''^ ' ' Accustomed as we are to behold the marvellous applications of Science to the useful purposes of everyday life, how few of us take the trouble to inquire how this or that effect is produced which adds so much to our comfort, our enjoyment, and our wealth ! We delight in clean linen, but know not how soa]) is made ; we admire the varied hues of our clothing and our finery, but are ignorant of the processes by which such charming tints are obtained ; we know that the prosperity of our country depends greatly upon our success in certain manufactures, but, alas ! how little we know of the thought, care, and skill which are involved in their production, or of the means by which the various results are obtained. To give an insight into the Scientific Industries of our country, in a simple and easily understood form, is the object of the present work ; and it has been the Author's aim to instruct without tiring his reader with elaborate details. A systematic arrangement of the subjects treated has been purposely avoided, in order that the work may be regarded as a means of intellectual recreation rather than a severe study." REVIEWS. " It is a useful book of general information, and sliows how largely science enters into the industries of ever>'day life.— T/ie Daily Chronicle. " The work is a useful popular educator, and merits a wide circulation."— T/ie Liverpool I Onrier. " Mr. Watt has produced a very useful little volume, which Avill prove acceptable, not Kuly to schooll)()ys as a means whereby they may acquire a slight knowledge of the objects of sciontific industry, but to older people as a manual of ready reference." — The Sheffield Daihi Tchijraph. " it is an instructive and interesting book, and there are few who will not find in its pages some k)iowledg«' that will prove useful to them." — The Aberdeen Jonrnal. "The expositions are concisely set forth, and, as technicalities are avoided as much'as lK)Ssible, are eminently suited for popular reading and enlightenment." — The Dundee Advertiser. " If it is desirable that we should know about the articles of everyday use, this book will be found a capital instructor." — The Fife Herald. In the Press. BY THE SAME AUTHOR. Scientific Industries Explained. Vol. 11. Containing, amongst other subjects — The Electric Light. Tanning'. Cheese-Making. j Artificial Manures. Preservation of Food. Gases. Scientific Agriculture. Vulcanized India-Rubber Manufacture of Glue, i Tartaric Acid. Stained Glass. | Borax. Etc. etc. etc. I Gelatine. I Galvanic Batteries, j Nickel-Plating. Citric Acid. Magnesia. Oils. w. & k:. J0 3Ei:)Nrsxo3sr, EDINBURGH, AND 6 PATERNOSTER BUILDINGS, LONDON, E.G. Noiv Ready. JOHNSTON'S ILLIJSTEATIOFS OE MAOTETISM km ELECTEICITT. By WILLIAM LEES, M.A, LECTURER ON NATURAL PHILOSOPHY, EDINBURGH. This Series of Illustrations will be found in every way adapted to the purposes of Instruction in the important • branches of Magnetism and Electricity. The Diagrams are large and distinctly coloured, and are therefore well suited for large Halls or Schoolrooms. Each Sheet is accompanied by a Handbook descriptive of the several Illustrations, and giving the leading principles of the Sciences in a clear and concise manner. The Publishers have great confidence in recommending the Series to Lecturers and Teachers. Sheet No. 1. Magnetism. Sheet No. 2. Frictional Electricity. Sheet No. 3. Voltaic Electricity. Sheet No. 4. The Electric Telegraph. Sheet No. 5. Electro-Deposition of Metals. By Alex. Watt, London. Size, 50 by 42 inches. Price on Cloth, EoUer, and Varnished, 12s. each; Unvarnished, 10s. each; on Cloth, folded up (Unvarnished), 12s. each. A Handbook is given (gratis) with each Sheet. REVIEWS. " They are wonderfully well got up, accurate, and calculated to save teachers a world of trouble." — The Schoolmaster. ''Like everything that emanates from the Messrs. Johnston, these Sheets are beautifully executed and scientifically arranged.'^ — The Educational News. " The drawing and colouring are so uniformly excellent that the Diagrams arrest the attention at once." — The Practical Teacher. W. & A. K. JOHNSTON, Edinburgh; and 6 Paternoster Buildings, London, B.C. / 7nf