THE RAVAGES OF BOOK-WORMS
At a meeting of the Massachusetts Historical Society, held February 9, 1893, Dr. Samuel A. Green, after showing two volumes that had been completely riddled by the ravages of insects, as well as some specimens of the animals in various stages, made the following remarks:—
For a long period of years I have been looking for living specimens of the so-called “book-worm,” of which traces are occasionally found in old volumes; and I was expecting to find an invertebrate animal of the class of annelids. In this library at the present time there are books perforated with clean-cut holes opening into sinuous cavities, which usually run up the back of the volumes, and sometimes perforate the leather covers and the body of the book; but I have never detected the live culprit that does the mischief. For the most part the injury is confined to such as are bound in leather, and the ravages of the insect appear to depend on its hunger. The external orifices look like so many shot-holes, but the channels are anything but straight. From a long examination of the subject I am inclined to think that all the damage was done before the library came to this site in the spring of 1833. At all events, there is no reason to suppose that any of the mischief has been caused during the last fifty years. Perhaps the furnace-heat dries up the moisture which is a requisite condition for the life and propagation of the little animal.
Nearly two years ago I received a parcel of books from Florida, of which some were infested with vermin, and more or less perforated in the manner I have described. It occurred to me that they would make a good breeding farm and experiment station for learning the habits of the insect; and I accordingly sent several of the volumes to my friend Mr. Samuel Garman, who is connected with the Museum of Comparative Zoology at Cambridge, for his care and observation. From him I learn that the principal offender is an animal known popularly as the Buffalo Bug, though he is helped in his work by kindred spirits, not allied to him according to the rules of natural history. Mr. Garman’s letter gives the result of his labours so fully as to leave nothing to be desired, and is as follows:—
“Museum of Comparative Zoology, Cambridge, Mass., February 7, 1893.
“Dr. Samuel A. Green, Boston, Mass.
“Sir,—The infested books sent for examination to this Museum, through the kindness of Mr. George E. Littlefield, were received July 15, 1891. They were inspected, and, containing individuals of a couple of species of living insects, were at once enclosed in glass for further developments. A year afterward live specimens of both kinds were still at work. Besides those that reached us alive, a third species had left traces of former presence in a number of empty egg-cases.
“Five of the volumes were bound in cloth. On these the principal damage appeared at the edges, which were eaten away and disfigured by large burrows extending inward. Two volumes were bound in leather. The edges of these were not so much disturbed; but numerous perforations, somewhat like shot-holes externally, passed through the leather, enlarging and ramifying in the interior. As if made by smaller insects, the sides of these holes were neater and cleaner cuttings than those in the burrows on the edges of the other volumes.
“The insects were all identified as well known enemies of libraries, cabinets, and wardrobes. One of them is a species of what are commonly designated ‘fish bugs,’ ‘silver fish,’ ‘bristle tails,’ &c. By entomologists they are called Lepisma; the species in hand is probably Lepisma saccharina. It is a small, elongate, silvery, very active creature, frequently discovered under objects, or between the leaves of books, whence it escapes by its extraordinary quickness of movement. Paste and the sizing or enamel of some kinds of paper are very attractive to it. In some cases it eats off the entire surface of the sheet, including the ink, without making perforations; in others the leaves are completely destroyed. The last specimen of this insect in these books was killed February 5, 1893, which proves the species to be sufficiently at home in this latitude.
“The second of the three is one of the ‘Buffalo Bugs.’ or ‘Carpet Bugs,’ so called; not really bugs, but beetles. The species before us is the Anthrenus varius of scientists, very common in Boston and Cambridge, as in other portions of the temperate regions and the tropics. Very likely the ‘shot-holes’ in the leather-bound volumes are of its making, though it may have been aided in the deeper and larger chambers by one or both of the others. The damage done by this insect in the house, museum, and library is too well known to call for further comment. Living individuals were taken from the books nearly a year after they were isolated.
“The third species had disappeared before the arrival of the books, leaving only its burrows, excrement, and empty egg-cases, which, however, leave no doubt of the identity of the animal with one of the cockroaches, possibly the species Blatta Australasiæ. The cases agree in size with those of Blatta Americana, but have thirteen impressions on each side, as if the number of eggs were twenty-six. The ravages of the cockroaches are greatest in the tropics, but some of the species range through the temperate zones and even northward. An extract from Westwood and Drury will serve to indicate the character of their work:—
“‘They devour all kinds of victuals, dressed and undressed, and damage all sorts of clothing, leather, books, paper, &c., which, if they do not destroy, at least they soil, as they frequently deposit a drop of their excrement where they settle. They swarm by myriads in old houses, making every part filthy beyond description. They have also the power of making a noise like a sharp knocking with the knuckle upon the wainscotting, Blatta gigantea being thence known to the West Indies by the name of drummer; and this they keep up, replying to each other, throughout the night. Moreover, they attack sleeping persons, and will even eat the extremities of the dead.’
“This quotation makes it appear that authors as well as books are endangered by this outlaw. With energies exclusively turned against properly selected examples of both, what a world of good it might do mankind! The discrimination lacking, the insect must be treated as a common enemy. As a bane for ‘silver fish’ and cockroaches, pyrethrum insect powder is said to be effectual. For a number of years I have used, on lepisma and roach, a mixture containing phosphorus, ‘The Infallible Water Bug and Roach Exterminator,’ made by Barnard & Co., 7 Temple Place, Boston, and, without other interest in advertising the compound, have found it entirely satisfactory in its effects. Bisulphide carbon, evaporated in closed boxes or cases containing the infested articles, is used to do away with the ‘Buffalo Bugs.’—Very respectfully yours,
“Samuel Garman.”
I can remember that many years ago there was to be seen in the bookshop of John Penington, Philadelphia, a book-worm preserved in spirits in a vial. The manner in which this species of teredo penetrates wood and leather as well as paper is not the least curious of its habits.
The great amount of injury inflicted by boring-insects in books, wood, and all weak substances is sufficient reason for giving so much space to this subject. From a ship to a manuscript, nothing is safe from them.
PAPIER-MÂCHÉ
REPAIRING TOYS—MAKING GROUNDS FOR PICTURES AND WALLS—CARTON-CUIR AND CARTON-PIERRE
Soft paper, when mixed with water, gum, or, better still, with flour-paste, forms a substance which can be moulded to any form, and which, when dry, will be as hard as cardboard. Its hardness and durability may be increased by mingling with it many substances.
Combined with soft leather in small fragments or with the dust of leather, it forms what the French call carton-cuir. In this, or even in its natural state—that is, paper and paste—papier-mâché, as it is termed, can under pressure be made as hard as any wood. I have seen all kinds of articles of furniture made from it. In America there are manufactories in which pails or buckets, tubs, firkins, and even durable boats, are thus manufactured. There is in Bergen, Norway, a church built entirely of it mixed with lime. For certain kinds of mending it is very valuable.
Though not so plastic as clay, papier-mâché can, with a little practice, be moulded into any form. It consists simply of pasting piece on to piece, pressing it meantime as much as possible with the fingers or a wooden implement like a pestle. The pressure should be applied as it gradually dries. Any one can thus make very hard cardboard with a bread-roller on a board.
If you have the cardboard cover of a book badly damaged, with even a portion gone, it can be restored by using papier-mâché in which a solution of glue or gum has been infused. Glue it specially at the edges. For such repairing take paper-dust or pulp, combined with gum-arabic in alum-water solution, or simply the gum. This is easily moulded and smoothed into any cracks or torn places.
If parchment be torn away it is easily replaced. Cut a piece to replace the missing portion, dampen it and the edge which it is to join till quite soft, then glue the two together, using pressure. I have just effected this myself with a cover of which half was gone, and the mending is hardly visible. Use the broad knife freely to press down the edges.
By combination with a mixture of nitric or sulphuric acid and water, soft paper becomes parchment-like and very hard. This requires careful experimenting, for its success depends on the quality of the acid and the texture of the paper. Very remarkable results have been obtained from this, such as material resembling ivory, horn, and tortoise-shell, in large blocks.
Waste-paper is so common and cheap that papier-mâché can always be made anywhere. It is well adapted to close cracks in wood, walls, or elsewhere; and for those who wish for an employment or amusement, it affords endless facilities. One of these is the mending or making of toys.
A common mask is made as follows. On a face carved in wood and oiled there is spread common coarse soft paper wetted, which is carefully pressed down, and more paper and paste added, till it is of the requisite thickness. It is then, when rather dry, taken off and left to dry perfectly. It is then painted and varnished. Should a mask be broken, wet it, paste glue-paper over it, and paint it again.
Papier-mâché is popularly synonymous with that which is trashy and sham in art, simply because its capacities and applications are not known. Thus leather-work was long despised as only affording imitations of carved wood. But in the hands of a true artist—that is, of an original designer, who applies, and not a mere artisan, who imitates or copies—papier-mâché is as much a subject for art as any other material. It can be used in many ways, more or less allied to mending, as are all arts. Thus paper in fine powder, or reduced to a fine paste—or pulp—can be, with a little practice, mixed with gum and painted with a brush on a surface so as to produce relief. A very little elevation or depression thus serves to produce grounds which may serve to give light or shadow to pictures. Thus pastel painting or crayon in colours rubbed in, which has always been, even in the most vigorous hands, a weak or “softly sweet” art, may be made very vigorous by firmly relieving and roughening the ground; for, as the great American painter, Allston, often strengthened his colours by mixing sand with them, so pastel painting which lacks “sand” can have it supplied by mixing it with the gum for the ground.
To understand this process more clearly, let it be observed that, as the illuminators of mediæval manuscripts gave relief and the appearance of solidity to gold by making a raised surface with a powder of gesso (plaster of Paris) and clay and gum, so this principle can be carried out to a far greater extent by giving relief to a ground. Here those of limited views, who never get beyond the merely artisan stage of art, will at once decry this as shamming, and as imitating effect by the aid of modelling, and not being true art, quite forgetting that all is true to genius, and everything more or less sham in the mere imitation.
Having a surface, either panel or Bristol board, which latter had better be pasted to a panel or good thick solid cardboard, begin by taking a little gum or glue in tolerably fluid solution on the point of a brush, and incorporating with it the paper pulp or cloth-dust to a very soft paste, with which paint what is to be in relief. The same effect is produced in oil by using a heavier, thicker kind of paint. That is all the difference, one being as legitimate as the other. By intermixing chalk or sand or clay, and by using glass-paper where the crayon, &c., refuse to take easily, the relief adapts itself to every substance. In this, as in every process known, the artist must at first experiment a little, according to his materials.
Solid sheets of fine hard paper, with strong paste between, when passed between rollers form a kind of papier-mâché which, is as hard as wood, fire-proof, and, what is most singular, more durable than iron. Wheels for railway carriages are often made of it, and they never warp under the action of heat or cold, neither do they crack nor bend. You can make this cardboard for yourself of very good quality by this process:—Take a sheet of writing-paper—the better the quality the better the result will be—cover it with good flour-paste in which there is a little alum and glue and a few drops of oil of cloves, which latter will prevent paste from turning or souring. Then lay on this another sheet, apply another coat of paste, and when it is a little dry or past the softer stage, yet while still capable of adhesion, lay the sheets on a hard, smooth slab or table, and pass a roller over them, at first gently, but eventually frequently, and with force. Add as many sheets as necessary for the thickness required. It will be understood that if the surface on which this sheet is formed were an intaglio-cut die or mould, the cardboard when taken up would present a bas-relief of it as hard as any wood, and the whole would form a panel which could be used for the side of a box or to be set in a cabinet. If made of good paper and firmly rolled, this panel will be in every respect equal to wood for all decorative purposes.
As anybody who can carve wood at all can cut moulds, and as a wooden mould, if kept well oiled (or otherwise secured from yielding to moisture), will serve for papier-mâché and leather or wood-paste casting, it is remarkable that such work is so very little practised by the students of the minor arts. That such panels can be very easily and rapidly made I know by experience; that the materials for the work are cheap speaks for itself; and, finally, that beautiful panels for cabinets and doors, whether made of carved wood, stamped leather, or papier-mâché bring a very good price will also be most apparent to anybody who will go to a fashionable cabinetmaker and order them. Thus we will say that a small plain cabinet costs £5. Put into it six panels, really costing about 6d. each to mould, and the price will be £10. Such pressed panels are admirably adapted for binding books, as, when properly made and dried, they cannot warp or bend. If covered with relief they may be made very beautiful. Simply blackened or browned, then rubbed with oil, varnished with Soehnée, No. 3, and rubbed by hand, they are as beautiful as polished wood or leather.
Papier-mâché, pulp, or paper powder can be combined with caoutchouc or indiarubber, which latter can be itself dissolved in benzine, camphine, sulphuric ether, and other solvent mediums, so as to form a paste which becomes like indiarubber when dry or as it hardens. Mixed with sulphur this forms vulcanite. Or it may be combined with white colouring matter of almost any kind. This can be applied to mending the broken noses of dolls, or any other wounds which these pretty semblances of humanity often receive, their beauty being unfortunately generally more shortlived than that of their prototypes. The final finish of such reparation is a coat of paint. In many cases this is better when rubbed on with the finger than when directly painted. The reader who shall have studied this work will find no difficulty in restoring any toy.
I may, however, here remark that “no solution of india rubber can be well moulded without intimate intermixture of sulphur, aided by heat and pressure. This is a difficult process, and the amateur would do well, therefore, to purchase rubber composition, which he may do at any large shop in which rubber goods are made as a specialty” (Work, May 21, 1892).
It is easy to make any article of papier-mâché if the mere beginning of a form has once been shaped; because, after that is set, all that we have to do is to gradually paste one piece of paper on, here and there, till it is finished. This beginning is very easy if we have an object on which to begin. Thus take a vase or cup. Oil this, and then lay on and all around it soft, damp paper. Newspaper will do—a soft, white printing paper. Then, with a broad brush, lay on paste, and apply a second coat of paper. Press it meanwhile as hard as you can. Continue this till the papier-mâché is thick enough. When dry, take a penknife and cut a line through from top to bottom. Scale it off, and reunite the edges with strong glue; then paste over the line of junction a strip of paper. Then you will have a cup.
If it be rough, cut it smooth and use glass-paper. When finished it may be painted or covered with wet leather, which can be worked into relief. Or it may be made to look like ivory by the process elsewhere described. Paper may in this process be combined with soft leather rags; as, for instance, pieces of old gloves out of which the thread has been taken, old chamois, bookbinders’ clippings, or the like. This forms effectively leather.
Carton-pierre, or stone-paper, is a very useful composition, which is very fully described by George Parland in Work, July 2, 1893. It consists of paper scraps, in the proportion of an ordinary washing boiler or copper one-half full of boiling water and about one-half paper waste. Add two pounds of best flour-paste; also, in a separate vessel, a quart of water, into which sprinkle a handful of fine plaster of Paris. Let it stand ten minutes before mixing it. “When the paper in the copper has become a fine pulp add the flour-paste, keeping the whole well stirred. Fifteen minutes after add the plaster, and a few minutes later rake out the fire from under the boiler. Have ready three pails of fine ground whiting; pour in one pail of whiting and stir up well, adding more whiting till the stick used to stir will stand of itself in the mixture. Let it cool, and it will be ready for use.
“Some firms,” writes Mr. Parland, “add powdered alum in the boiling process, others add one pint of boiled linseed-oil; but if made according to the previous directions, an excellent carton-pierre will result, which gives very fine impressions from moulds. If it be cast in a plaster mould, the latter should have two or three coats of shellac varnish, and then be well oiled.... In using the carton, sprinkle some fine plaster of Paris on a bench, and taking a lump of the newly made carton, mix it well with dry plaster, adding more plaster, as bakers would add flour to their dough. Having worked it well in this way until it will not stick to the fingers, with clean hands roll pieces very smooth in the palms, or on a smooth level board, and press each roll into the cavities and hollows of the mould, often wetting the edges of the carton in the mould before adding a fresh piece to it. The casts must not be more than from an eighth to a quarter of an inch in thickness, except at the outside edges of the mould.... The casts must stand about twenty-four hours, and then be baked in not more than 100° heat.”
The reader who is specially interested in papier-mâché will find a series of articles on the subject in Work, Nos. 3, 6, 12, 17, 22, 25.
Pipeclay, to which calcined magnesia, whiting, or baryta may be added or omitted according to the body required, may be combined with papier-mâché and gluten, such as gum-arabic or dextrine or flour-paste, which will form under pressure, or even by hand-rolling, a very hard and finely grained substance, which is specially adapted to painting pictures. Plates or tavole are sold very cheaply in Florence of papier-mâché, which are as hard, heavy, and glossy as ebony. It is not generally realised that an expensive hydraulic-press or steam-engine is not needed by the amateur to harden papier-mâché. A common bread-roller, passed many times over the material, will work it “down and in,” quite as well as direct pressure, and very often much better.
Papier-mâché mixed and macerated with indiarubber or gutta-percha and benzole (vide Indiarubber) forms in many cases a very good substitute for leather. It can also be combined with flexible varnish to make leather. Very valuable soles can be made, or broken ones repaired, by taking card or pasteboard and soaking it in a hot solution of indiarubber. These waterproofed soles, whether of cardboard or leather, are easily prepared, as easily applied and renewed, and they will keep the true sole from wearing out forever, if renewed.
Singular as it seems, there are not many persons who are familiar with the properties or texture of so familiar a substance as paper. We know that if wetted it grows soft, but still remains, as it were, knotty, and that when chewed it does not properly dissolve. Yet if the reader will take a piece of thoroughly wetted paper, and knead or macerate it with a knife for some time with gum in solution, he will find it gradually becomes a soft paste, as flexible and as capable of moulding as putty or clay. This is not the same as papier-mâché, which consists of paper merely wet or mixed and boiled with paste, and contains fibre and knottiness. The finely macerated paper, combined with an adhesive, is ductile, impressionable, sets well, and readily receives pressure on rolling, under which it becomes extremely hard. Paper thus completely softened is readily made into sheets, and may be easily applied not only to fill up worm-holes in leaves and completely torn-away corners, &c., but is very useful for cracks and cavities in wood and other substances. It may be made up with any gums, such as gum-arabic, dextrine, fish-glue, and also with caseine, gutta-percha, varnish, and most of the substances used in cements. Paper when thus softened and mixed with, e.g., fine glue and glycerine, or with flour-paste, can be moulded and applied in ornamental forms to any surface.
There is this great difference between simply wet paper, however wet it may be, and that which is completely softened by maceration. The former is always lumpy, the latter passes under the blade of a knife like soft clay or putty. When made up with gum, glue, and glycerine, or strong paste, it is, when dry, like light wood, but less brittle. Kneaded with Indiarubber solution and glue, it becomes like leather, and can be used in several varieties of repairs. Rolled into sheets, this composition makes very good and cheap artificial leather for hangings. To manufacture these, spread the composition with a broad brush or dabber on a slate or marble table, and when rather dry pass over it a wooden roller. Some practice is needed not to roll it when too soft. If intaglio patterns are cut in the roller, the sheets will give them in relief. It is worth noting here that a great many pieces of old hangings sold as leather are really only made of papier-mâché, or carton-cuir, and glue. These hangings, whether of leather or counterfeited, can be often bought in a damaged condition very cheaply, and can be easily restored with this composition, to great profit. When mixed with white lead, or oil paint and glue, soft paper becomes harder and firmer, and under pressure is as hard and heavy as any wood. White paper with holly wood or white larch or lime-tree wood in powder, and white gelatine—better if bone or ivory dust be added, with a little Naples yellow (oil)—forms a beautiful cement.
It will be seen by what I have written that cavities, holes, cracks, and defects in most substances, including wood and leather, can be perfectly remedied with paper in combination with glue, gum, or other substances; and as it is always to be obtained, a knowledge of its nature and applications cannot fail to be of value to all menders and restorers.
Papier-mâché, like all substantial or putty-like cements, involves moulding or casting. This subject is exhaustively treated in the Vollständige Anleitung zum Formen und Giessen, by Eduard Uhlenhuth; Vienna, A. Hartleben, price 3s. On the subject of paper consult the Handbuch der praktischen Papier-Fabrikation, by Dr. Stanislaus Mierzinski, three volumes, which is not only the latest, but by far the most comprehensive, work on the subject with which I am acquainted. And here I may observe in this connection that if my references have been chiefly to German works, it is because, in the minor technical applications of chemistry to the arts, and in preparing intelligible practical treatises on such subjects, the Germans have been, especially of late, by far the first nation in Europe.
I may mention that since writing the foregoing passages I purchased, for a mere trifle, in Florence two carved heads of the fourteenth century in walnut wood. They had suffered very much from time and wanton abuse, their noses having been hacked off. I made a mixture of soft paper-paste and gum-arabic, working the two thoroughly in together with a knife-blade till the composition was as soft as butter. This thorough maceration is essential to produce a durable body. With this I filled up the holes, made new noses, and painted the whole with Vandyke brown, or brown-black. In a few minutes the restoration was complete, and the heads which had cost one franc each are now worth at least thirty francs. I should say that the portions restored are as hard as the original wood.
It is not always an easy matter to reduce paper to a perfectly soft paste, such as is called in French papier-pourri. A small quantity can be mashed with a knife-blade and flour-paste or gum. A large quantity is prepared as follows:—
Take clippings of paper and leave them a long time in water, which must be occasionally changed. When quite dissolved or soft, bray the paper in a mortar, and finally boil in very hot water. To give it consistency, add flour-paste or gum. This makes a very fine cement, which will receive the most delicate impression. It is invaluable for all kinds of dry mending.
As I have shown, it can be applied to make or mend defective leaves of books, to fill up worm-holes in leaves, to repair drawings and pictures on wood or canvas, and when mixed with any gum which sets hard, to restore, add to, fill, or imitate woodwork. Under pressure and combined with different powders it becomes as hard as ebony and fire-proof. Its extraordinary value and general utility are as yet very far from being much known.
MENDING STONE-WORK
MOSAICS—CERESA-WORK—PORCELAIN OR CROCKERY MOSAIC
Mending or repairing stone, involving its imitations, is a widely extended branch of technical science, and one which has of late years called forth much invention. The most widely spread and ancient means of uniting and repairing this material is mortar, or the mixture of burned and then slacked lime with water. Lime is made most commonly from limestone or marble. It improves in quality when carbonate of lime in organic formation, such as sea-shells, is used; and there are degrees of excellence in these, from common oyster-shells to others of a finer kind, such as those with which the brilliantly white and hard chunam of India is made. In certain places mortar, when well made, becomes with age as hard as flint. In American towns, where anthracite coal is burned, it rots away in chimneys under the influence of sulphurous acid with great rapidity. In the Pacific Islands, where lime is made from delicate small sea-shells or coral, and mortar is like a paint or enamel, a missionary has recorded that, when he taught the natives how to make it, they whitewashed everything, even to the children, who thus became white people.
The misapplied word mastic, which suggests a gum, refers to certain modifications of mortar into which oil enters; also the oxides of lead or zinc. “Oil forms with these an insoluble soap, which includes or binds the other materials, forming, after one month’s drying, a very hard substance,” which some say is as hard as stone, but which depends entirely on the quality and combination; for I have seen so-called mastic applied to coating cheaply built houses, which cracked or crumbled away like mere plaster of Paris.
To thoroughly amalgamate mastics, it is usual to put their ingredients into casks which are two-thirds filled, and then revolved by machinery. The oil is then added. At least two days are required for the process. The following recipes for mastics are among the best, having been approved by Lehner. It may here be remarked, once for all, not only as regards mastics, but all recipes in this work, that unless the materials indicated are of the very best quality, and the processes be most thoroughly carried out, the experimenter cannot expect complete success. More than this, the experimenter must not be satisfied with a single trial. If every recipe could be at once executed by every cook, we should find the most exquisite cookery on every table in Europe. I once published the correct recipe for making objects of a peculiar kind of papier-mâché hardened. It was very easy to make. I had seen specimens of the ware, and I received the recipe from the inventor. Moreover, a great deal of money had been made by it. However, soon after I had published it I received an indignant letter from the head of a large manufacturing house, stating that they had tried my recipe and utterly failed!
French Mastic:—
| Quartz or flint sand, | parts | 300 |
| Powdered quicklime, | ” | 100 |
| Litharge, | ” | 50 |
| Linseed-oil, | ” | 35 |
Paget’s Mastic:—
| Flint sand | 315 |
| Washed chalk | 105 |
| White lead | 25 |
| Minium | 10 |
| Sugar of lead in solution | 45 |
| Linseed-oil | 35 |
The paste or “dough” thus formed should be ground with horizontal rollers in a mill, such as is used for chocolate, until all the ingredients are very thoroughly amalgamated.
A very good cement for mending, especially where the objects are exposed to water, whether they be of stone or earthenware, is made as follows:—
| Powdered glass | 40 |
| Washed litharge | 40 |
| Linseed-oil varnish | 20 |
The powdered glass is prepared by heating glass red-hot, casting it into water, grinding and sifting it. This powder is saturated with the linseed-oil varnish, and heated in a kettle. This cement sets hard in three days. Lehner observes that glass-powder serves in such recipes to resist the action of acids, &c., since it forms in combination on the surface a glaze of great hardness; that is, the glass and lead form a chemical combination. Pulverised calcined glass therefore acts not as an “indifferent” but as a chemical ingredient.
Caseine, or Cheese, forms the basis of several recipes for mending stone, as when there are holes in a block or the mortar has given way. To prepare it for use (Lehner), we let milk stand in a cool place, skimming away with the utmost care all the cream. Place this on a filter, and pour on it rain-water till it is purified from every trace of lactic acid; then tie it in a cloth, boil it in water, and spread it on blotting-paper in a warm place, when it will be a horn-like substance. This will keep for a long time. To prepare it for use, rub it in a saucer with water.
To mend stone make the following:—
| Caseine | 12 |
| Slacked lime | 50 |
| Fine sand | 50 |
Another recipe:—
Boil new cheese in water till it draws out in threads, stirring in slacked lime and sifted wood-ashes in the following proportions:—
| Cheese | 100 |
| Water | 200 |
| Slacked lime | 25 |
| Wood-ashes | 20 |
This may also be used to close cavities in trees or in wood.
A cheese cement for stone, and for many other purposes, is made as follows. It may be kept for a long time, and is very durable (Lehner):—
| Caseine | 200 |
| Calcined lime | 40 |
| Camphor | 1 |
This must be closely incorporated and kept well corked. When it is to be used mix it with water, and apply at once.
The following cement was used by the Romans especially in setting mosaics. It becomes as hard as marble, and sets with great rapidity:—To one quart of milk add the white of five eggs, and stir in powdered quicklime till a paste is formed. This composition may be used to repair or make scagliola, which is fragments of marble or stone embedded in a hard mass. When it sets, polish the surface with rasps, and rub down with a rough stone, and finally polish with marble dust, and then emery or tripoli. Beautiful slabs for tables, columns, floors, and walls can thus be made. It is valuable for repairing.
Ceresa is allied to this. We make a basis of this or any other cement which will hold firmly, and press into the surface powdered glass, which may be fine or of any degree of coarseness. Coarse grains shine most brilliantly; fine powder is best adapted to delicate shading. The effect is best when mosaic stones and gold cubes are sparingly introduced. To make the gold cubes, take two small panes of window glass, cover one side of each with varnish or mastic cement, lay between them gold-leaf, and join them. Very beautiful pictures can be made in this manner. Nor is it at all necessary that they should be finely executed for ordinary decoration. All that is needed for this beautiful and little-known art is the cement, a quantity of glass or stone of different colours, and a mortar and pestle. The mosaic cubes, with those of gold, can be bought in London.
Allied to this is an art which I believe I can claim to have invented. It consists of breaking waste chinaware, crockery, or fictile ware into small squares or triangles, and setting them as mosaic in cement. The advantage of it is the cheapness of the material, and the infinite number of shades of colour which can be selected for it. Its disadvantage is, that it will not wear as a pavement, but it is perfectly adapted to walls.
A strong, coarse cement for brick or stone work in building is made as follows:—
| Slacked lime | 40 |
| Brick-dust | 10 |
| Iron filings | 10 |
| Ox-blood | 8 |
| Water | 8 |
The blood is stirred as it comes from the slaughtered beast with a broom for ten minutes to break the fibre. It should then be mixed with the water and kneaded with the powder. Glue may be substituted for the blood. This cement, if properly made, sets very hard and adhesively.
For tiles, bricks, or composition:—
| Slacked lime | 100 |
| Sifted stone-coal ashes | 50 |
| Stirred ox-blood | 15 |
It may be observed that many of the cheaper cements can be employed to form large bricks by combination with broken stone or rubble, gravel, pebbles, brickbats, &c. Another method, called Concrete, is to make cases of boards, and to form a solid wall by pouring in the mixture, or ramming it down, according to its hardness. Thus a house is made entirely in one piece; but its excellence depends entirely on the quality of the cement employed, and on the care taken in building. Simple lime mortar, if not of a superior quality, hastily formed, as I have seen, is very apt to crack and break off. Where hydraulic cement is cheap and good, houses can be built as firm as granite. A good and strong cement of this kind can be made as follows:—
| Burned lime | 10 |
| Caseine | 12 |
| Hydraulic cement | 30 |
The proportions may be very much varied in such cements according to their price, but generally with a satisfactory result.
Fractures or discolorations in marble, as in statuary, are so perfectly repaired in Florence that the juncture is not perceptible. Even dark spots are drilled out. The process is to drill a round concave hole, and cut the piece to be inserted so as to exactly fit as a convex plug. It is then fastened in with transparent mastic or other clear cement. It will be seen, on due consideration, that this is extremely ingenious, because by it alone can a perfectly tight fit be secured. By turning the plug in the hollow it speedily grinds itself into an accurate plug; so when the cement is applied it can be reduced to a minimum—in fact, by this means the line of junction is reduced to its finest limit.
Where a very strong cement is needed for stone-work, it can be prepared by mixing a fine cement powder—e.g., Portland cement—with liquid silicate of soda. As it dries almost at once, it must be promptly applied. It is particularly well adapted for building under water, since it then becomes extremely hard. Before applying it smear the stone with pure silicate.
The following is highly commended by Lehner:—
Mending statues of gypsum or plaster of Paris is allied to stone-work. The broken edges are washed with water till no more is absorbed and the surface remains wet. Then stir fresh calcined white plaster of Paris with much water to a thin paste, and continue to stir this till it is cold. Then rapidly paint this paste on the broken edges, continuing to press the two together till they set hard.
It is, says Lehner, a peculiarity of gypsum that when mixed with alum dissolved in water it takes a much longer time to harden, but is very much harder in the end. Thus, if we let the powdered gypsum lie for twenty-four hours in alum-water, dry it, and then calcine it again, the powder when mixed with water sets to a stone as hard as marble.
Plaster of Paris and alum, combined with the fine powder of calcined glass, form a very hard and durable cement, of very general utility in all mending of stone-work.
For an exhaustive work on the subject of not only mending stone-work, but also of making artificial stone and many cements, as well as combining and adapting to use paper, cellulose, sawdust and shavings, gypsum, chalk, glue, &c., including not only ancient but also the most recent recipes, consult Die Fabrikation künstlicher plastischer Massen, by Johannes Hofer; Leipzig, A. Hartleben, price 4s.