Part 27

«Decolorization of Carbolic Acid.»—To decolorize the acid the following simple method is recommended. For purifying carbolic acid which has already become quite brown-red on account of having been kept in a tin vessel, the receptacle is exposed for a short time to a temperature of 25° C. (77° F.), thus causing only a part of the contents to melt. In this state the acid is put into glass funnels and left to stand for 10 to 12 days in a room which is likewise kept at the above temperature. Clear white crystals form from the drippings, which remained unchanged, protected from air and light, while by repeating the same process more clear crystals are obtained from the solidified dark colored mother lye. In this manner 75 to 80 per cent of clear product is obtained altogether.

«Disguising Odor of Carbolic Acid.»—Any stronger smelling substance will disguise the odor of carbolic acid, to an extent at least, but it is a difficult odor to disguise on account of its persistence. Camphor and some of the volatile oils, such as peppermint, cajeput, caraway, clove, and wintergreen may be used.

«To Restore Reddened Carbolic Acid.»—Demont’s method consists in melting the acid on the water bath, adding 12 per cent of alcohol of 95 per cent, letting cool down and, after the greater part of the substance has crystallized out, decanting the liquid residue. The crystals obtained in this manner are snowy white, and on being melted yield a nearly colorless liquid. The alcohol may be recovered by redistillation at a low temperature. This is a rather costly procedure.

CARBOLIC SOAP: See Soap.

«CARBOLINEUM:»

See also Paints and Wood.

«Preparation of Carbolineum.»—I.—Melt together 50 parts of American rosin (F) and 150 parts of pale paraffine oil (yellow oil), and add, with stirring, 20 parts of rosin oil (rectified).

II.—Sixty parts, by weight, of black coal tar oil of a specific gravity higher than 1.10; 25 parts, by weight, of creosote oil; 25 parts, by weight, of beechwood tar oil of a higher specific weight than 0.9. Mix together and heat to about 347° F., or until the fumes given off begin to deposit soot. The resulting carbolineum is brown, and of somewhat thick consistency; when cool it is ready for use and is packed in casks. This improved carbolineum is applied to wood or masonry with a brush; the surfaces treated dry quickly, very soon loose the odor of the carbolineum, and are effectively protected from dampness and formation of fungi.

CARBON PRINTING: See Photography.

CARBON PROCESS IN PHOTOGRAPHY: See Photography.

CARBONYLE: See Wood.

CARBUNCLE REMEDIES: See Boil Remedy.

CARDS (PLAYING), TO CLEAN: See Cleaning Preparations and Methods.

CARDBOARD, WATERPROOF GLUE FOR: See Adhesives under Cements and Waterproof Glues.

CARDBOARD, WATERPROOFING: See Waterproofing.

CARMINATIVES: See Pain Killers.

CARPET PRESERVATION: See Household Formulas.

CARPET SOAP: See Soap. {148}

CARRIAGE-TOP DRESSING: See Leather.

CARRON OIL: See Cosmetics.

CASE HARDENING: See Steel.

«Casein»

«Dried Casein, its Manufacture and Uses.»—For the production of casein, skimmed milk or buttermilk is used, articles of slight value, as they cannot be employed for feeding hogs or for making cheese, except of a very inferior sort, of little or no alimentive qualities. This milk is heated to from 70° to 90° C. (175°–195° F.), and sulphuric or hydrochloric acid is added until it no longer causes precipitation. The precipitate is washed to free it from residual lactose, redissolved in a sodium carbonate solution, and again precipitated, this time by lactic acid. It is again washed, dried, and pulverized. It takes 8 gallons of skimmed milk to make 1 pound of dry casein.

In the manufacture of fancy papers, or papers that are made to imitate the appearance of various cloths, laces, and silks, casein is very widely used. It is also largely used in waterproofing tissues, for preparation of waterproof products, and various articles prepared from agglomeration of cork (packing boards, etc.). With lime water casein makes a glue that resists heat, steam, etc. It also enters into the manufacture of the various articles made from artificial ivory (billiard balls, combs, toilet boxes, etc.), imitation of celluloid, meerschaum, etc., and is finding new uses every day.

Casein, as known, may act the part of an acid and combine with bases to form caseinates or caseates; among these compounds, caseinates of potash, of soda, and of ammonia are the only ones soluble in water; all the others are insoluble and may be readily prepared by double decomposition. Thus, for example, to obtain caseinate of alumina it is sufficient to add to a solution of casein in caustic soda, a solution of sulphate of alumina; an insoluble precipitate of casein, or caseinate of alumina, is instantly formed.

This precipitate ought to be freed from the sulphate of soda (formed by double decomposition), by means of prolonged washing. Pure, ordinary cellulose may be incorporated with it by this process, producing a new compound, cheaper than pure cellulose, although possessing the same properties, and capable of replacing it in all its applications.

According to the results desired, in transparency, color, hardness, etc., the most suitable caseinate should be selected. Thus, if a translucent compound is to be obtained, the caseinate of alumina yields the best. If a white compound is desired, the caseinate of zinc, or of magnesia, should be chosen; and for colored products the caseinates of iron, copper, and nickel will give varied tints.

The process employed for the new products, with a base of celluloid and caseinate, is as follows: On one hand casein is dissolved in a solution of caustic soda (100 parts of water for 10 to 25 parts of soda), and this liquid is filtered to separate the matters not dissolved and the impurities. On the other hand, a salt of the base of which the caseinate is desired is dissolved, and the solution filtered. It is well not to operate on too concentrated a solution. The two solutions are mixed in a receptacle provided with a mechanical stirrer, in order to obtain the insoluble caseinate precipitate in as finely divided a state as possible. This precipitate should be washed thoroughly, so as to free it from the soda salt formed by double decomposition, but on account of its gummy or pasty state, this washing presents certain difficulties, and should be done carefully. After the washing the mass is freed from the greater part of water contained, by draining, followed by drying, or energetic pressing; then it is washed in alcohol, dried or pressed again, and is ready to be incorporated in the plastic mass of the celluloid.

For the latter immersion and washing it has been found that an addition of 1 to 5 per cent of borax is advantageous, for it renders the mass more plastic, and facilitates the operation of mixing. This may be conducted in a mixing apparatus; but, in practice, it is found preferable to effect it with a rolling mill, operating as follows:

The nitro-cellulose is introduced in the plastic state, and moistened with a solution of camphor in alcohol (40 to 50 parts of camphor in 50 to 70 of alcohol for 100 of nitro-cellulose) as it is practiced in celluloid factories.

This plastic mass of nitro-cellulose is placed in a rolling mill, the cylinders of which are slightly heated at the same time as the caseinate, prepared as above; then the whole mass is worked by the cylinders until the mixture of the two {149} is perfectly homogeneous, and the final mass is sufficiently hard to be drawn out in leaves in the same way as practiced for pure celluloid.

These leaves are placed in hydraulic presses, where they are compressed, first hot, then cold, and the block thus formed is afterwards cut into leaves of the thickness desired. These leaves are dried in an apparatus in the same way as ordinary celluloid. The product resembles celluloid, and has all its properties. At 90° to 100° C. (194° to 212° F.), it becomes quite plastic, and is easily molded. It may be sawed, filed, turned, and carved without difficulty, and takes on a superb polish. It burns less readily than celluloid, and its combustibility diminishes in proportion as the percentage of caseinate increases; finally, the cost price is less than that of celluloid, and by using a large proportion of caseinate, products may be manufactured at an extremely low cost.

«Phosphate of Casein and its Production.»—The process is designed to produce a strongly acid compound of phosphoric acid and casein, practically stable and not hydroscopic, which may be employed as an acid ingredient in bakers’ yeast and for other purposes.

The phosphoric acid may be obtained by any convenient method; for example, by decomposing dicalcic or monocalcic phosphate with sulphuric acid. The commercial phosphoric acid may also be employed.

The casein may be precipitated from the skimmed milk by means of a suitable acid, and should be washed with cold water to remove impurities. A caseinate may also be employed, such as a compound of casein and an alkali or an alkaline earth.

The new compound is produced in the following way: A sufficient quantity of phosphoric acid is incorporated with the casein or a caseinate in such a way as to insure sufficient acidity in the resulting compound. The employment of 23 to 25 parts by weight of phosphoric acid with 75 to 77 parts of casein constitutes a good proportion.

An aqueous solution of phosphoric acid is made, and the casein introduced in the proportion of 25 to 50 per cent of the weight of the phosphoric acid present. The mixture is then heated till the curdled form of the casein disappears, and it assumes a uniform fluid form. Then the mixture is concentrated to a syrupy consistency. The remainder of the casein or of the caseinate is added and mixed with the solution until it is intimately incorporated and the mass becomes uniform. The compound is dried in a current of hot air, or in any other way that will not discolor it, and it is ground to a fine powder. The intimate union of the phosphoric acid and casein during the gradual concentration of the mixture and during the grinding and drying, removes the hydroscopic property of the phosphoric acid, and produces a dry and stable product, which may be regarded as a hyperphosphate of casein. When it is mixed with water, it swells and dissolves slowly. When this compound is mingled with its equivalent of sodium bicarbonate it yields about 17 per cent of gas.

CASEIN CEMENTS: See Adhesives.

CASEIN VARNISH: See Varnishes.

«CASKS:»

«To Render Shrunken Wooden Casks Watertight.»—When a wooden receptacle has dried up it naturally cannot hold the water poured into it for the purpose of swelling it, and the pouring has to be repeated many times before the desired end is reached. A much quicker way is to stuff the receptacle full of straw or bad hay, laying a stone on top and then filling the vessel with water. Although the water runs off again, the moistened straw remains behind and greatly assists the swelling up of the wood.

CASSIUS, PURPLE OF: See Gold.

CASKET TRIMMINGS: See Castings.

CASTS (PLASTER), PRESERVATION OF: See Plaster.

CASTS, REPAIRING OF BROKEN: See Adhesives and Lutes.

CASTS FROM WAX MODELS: See Modeling.

«Casting»

«Castings Out of Various Metals.»—Until recent years metal castings were all made in sand molds; that is, the patterns were used for the impressions in the sand, the same as iron castings are produced to-day. Nearly all of the softer metals are now cast in brass, copper, zinc, or iron molds, and only the silver {150} and German silver articles, like wire real bronze, are cast the old way, in sand. Aluminum can be readily cast in iron molds, especially if the molds have been previously heated to nearly the same temperature as the molten aluminum, and after the molds are full the metal is cooled gradually and the casting taken out as soon as cooled enough to prevent breaking from the shrinkage. Large bicycle frames have been successfully cast in this manner.

The French bronzes, which are imitations, are cast in copper or brass molds. The material used is principally zinc and tin, and an unlimited number of castings can be made in the mold, but if a real bronze piece is to be produced it must be out of copper and the mold made in sand. To make the castings hollow, with sand, a core is required. This fills the inside of the figure so that the molten copper runs around it, and as the core is made out of sand, the same can be afterwards washed out. If the casting is to be hollow and is to be cast in a metal mold, then the process is very simple. The mold is filled with molten metal, and when the operator thinks the desired thickness has cooled next to the walls, he pours out the balance. An experienced man can make hollow castings in this way, and make the walls of any thickness.

Casket hardware trimmings, which are so extensively used on coffins, especially the handles, are nearly all cast out of tin and antimony, and in brass molds. The metal used is brittle, and requires strengthening at the weak portions, and this is mostly done with wood filling or with iron rods, which are secured in the molds before the metal is poured in.

Aluminum castings, which one has procured at the foundries, are usually alloyed with zinc. This has a close affinity with aluminum, and alloys readily; but this mixture is a detriment and causes much trouble afterwards. While this alloy assists the molder to produce his castings easily, on the other hand it will not polish well and will corrode in a short time. Those difficulties may be avoided if pure aluminum is used.

Plaster of Paris molds are the easiest made for pieces where only a few castings are wanted. The only difficulty is that it requires a few days to dry the plaster thoroughly, and that is absolutely necessary to use them successfully. Not only can the softer metals be run into plaster molds, but gold and silver can be run into them. A plaster mold should be well smoked over a gaslight, or until well covered with a layer of soot, and the metal should be poured in as cool a state as it will run.

«To Prevent the Adhesion of Modeling Sand to Castings.»—Use a mixture of finely ground coke and graphite. Although the former material is highly porous, possessing this quality even as a fine powder, and the fine pulverization is a difficult operation, still the invention attains its purpose of producing an absolutely smooth surface. This is accomplished by mixing both substances intimately and adding melted rosin, whereupon the whole mass is exposed to heat, so that the rosin decomposes, its carbon residue filling up the finest pores of the coke. The rosin, in melting, carries the fine graphite particles along into the pores. After cooling the mass is first ground in edge mills, then again in a suitable manner and sifted. Surprising results are obtained with this material. It is advisable to take proportionately little graphite, as the different co-efficients of expansion of the two substances may easily exercise a disturbing action. One-fifth of graphite, in respect to the whole mass, gives the best results, but it is advisable to add plenty of rosin. The liquid mixture must, before burning, possess the consistency of mortar.

«Sand Holes in Cast-Brass Work.»—Cast-brass work, when it presents numerous and deep sand holes, should be well dipped into the dipping acid before being polished, in order thoroughly to clean these objectionable cavities; and the polishing should be pushed to an extent sufficient to obliterate the smaller sand holes, if possible, as this class of work looks very unsightly, when plated and finished, if pitted all over with minute hollows. The larger holes cannot, without considerable labor, be obliterated; indeed, it not infrequently happens that in endeavoring to work out such cavities they become enlarged, as they often extend deep into the body of the metal. An experienced hand knows how far he dare go in polishing work of this awkward character.

«Black Wash for Casting Molds.»—Gumlac, 1 part; wood spirit, 2 parts; lampblack, in sufficient quantity to color.

«How to Make a Plaster Cast of a Coin or Medal.»—The most exact observance of any written or printed directions is no guarantee of success. Practice alone can give expertness in this work. {151} The composition of the mold is of the most varied, but the materials most generally used are plaster of Paris and brick dust, in the proportion of 2 parts of the first to 1 of the second, stirred in water, with the addition of a little sal ammoniac. The best quality of plaster for this purpose is the so-called alabaster, and the brick dust should be as finely powdered as possible. The addition of clay, dried and very finely powdered, is recommended. With very delicate objects the proportion of plaster may be slightly increased. The dry material should be thoroughly mixed before the addition of water.

As the geometrically exact contour of the coin or medal is often the cause of breaking of the edges, the operator sometimes uses wax to make the edges appear half round and it also allows the casting to be more easily removed from the second half of the mold. Each half of the mold should be about the thickness of the finger. The keys, so called, of every plaster casting must not be forgotten. In the first casting some little half-spherical cavities should be scooped out, which will appear in the second half-round knobs, and which, by engaging with the depressions, will ensure exactness in the finished mold.

After the plaster has set, cut a canal for the flow of the molten casting material, then dry the mold thoroughly in an oven strongly heated. The halves are now ready to be bound together with a light wire. When bound heat the mold gradually and slowly and let the mouth of the canal remain underneath while the heating is in progress, in order to prevent the possible entry of dirt or foreign matter. The heating should be continued as long as there is a suspicion of remaining moisture. When finally assured of this fact, take out the mold, open it, and blow it out, to make sure of absolute cleanness. Close and bind again and place on a hearth of fine, hot sand. The mold should still be glowing when the casting is made. The ladle should contain plenty of metal, so as to hold the heat while the casting is being made. The presence of a little zinc in the metal ensures a sharp casting. Finally, to ensure success, it is always better to provide two molds in case of accident. Even the most practiced metal molders take this precaution, especially when casting delicate objects.

«How to Make Castings of Insects.»—The object—a dead beetle, for example—is first arranged in a natural position, and the feet are connected with an oval rim of wax. It is then fixed in the center of a paper or wooden box by means of pieces of fine wire, so that it is perfectly free, and thicker wires are run from the sides of the box to the object, which subsequently serve to form air channels in the mold by their removal. A wooden stick, tapering toward the bottom, is placed upon the back of the insect to produce a runner for casting. The box is then filled up with a paste with 3 parts of plaster of Paris and 1 of brick dust, made up with a solution of alum and sal ammoniac. It is also well first to brush the object with this paste to prevent the formation of air bubbles. After the mold thus formed has set, the object is removed from the interior by first reducing it to ashes. It is, therefore, allowed to dry, very slowly at first, by leaving in the shade at a normal temperature (as in India this is much higher than in our zone, it will be necessary to place the mold in a moderately warm place), and afterwards heating gradually to a red heat. This incinerates the object, and melts the waxen base upon which it is placed. The latter escapes, and is burned as it does so, and the object, reduced to fine ashes, is removed through the wire holes as suggested above. The casting is then made in the ordinary manner.

«Casting of Soft Metal Castings.»—I.—It is often difficult to form flat back or half castings out of the softer metals so that they will run full, owing mostly to the thin edges and frail connections. Instead of using solid metal backs for the molds it is better to use cardboard, or heavy, smooth paper, fastened to a wooden board fitted to the back of the other half of the mold. By this means very thin castings may be produced that would be more difficult with a solid metal back.

II.—To obtain a full casting in brass molds for soft metal two important points should be observed. One is to have the deep recesses vented so the air will escape, and the other is to have the mold properly blued. The bluing is best done by dipping the mold in sulphuric acid, then placing it on a gas stove until the mold is a dark color. Unless this bluing is done it will be impossible to obtain a sharp casting.

«Drosses.»—All the softer grades of metal throw off considerable dross, which is usually skimmed off; especially with tin and its composition. Should much of this gather on the top of the molten {152} metal, the drosses should all be saved, and melted down when there is enough for a kettle full. Dross may be remelted five or six times before all the good metal is out.

«Fuel.»—Where a good soft coal can be had at a low price, as in the middle West, this is perhaps the cheapest and easiest fuel to use; and, besides, it has some advantages over gas, which is so much used in the East. A soft-coal fire can be regulated to keep the metal at an even temperature, and it is especially handy to keep the metal in a molten state during the noon hour. This refers particularly to the gas furnaces that are operated from the power plant in the shop; when this power shuts down during the noon hour the metal becomes chilled, and much time is lost by the remelting after one o’clock, or at the beginning in the morning.

«Molds.»—I.—Brass molds for the casting of soft metal ornaments out of britannia, pewter, spelter, etc., should be made out of brass that contains enough zinc to produce a light-colored brass. While this hard brass is more difficult for the mold maker to cut, the superiority over the dark red copper-colored brass is that it will stand more heat and rougher usage and thereby offset the extra labor of cutting the hard brass. The mold should be heavy enough to retain sufficient heat while the worker is removing a finished casting from the mold so that the next pouring will come full. If the mold is too light it cools more quickly, and consequently the castings are chilled and will not run full. Where the molds are heavy enough they will admit the use of a swab and water after each pouring. This chills the casting so that it can be removed easily with the plyers.

II.—Molds for the use of soft metal castings may be made out of soft metal. This is done with articles that are not numerous, or not often used; and may be looked upon as temporary. The molds are made in part the same as when of brass, and out of tin that contains as much hardening as possible. The hardening consists of antimony and copper. This metal mold must be painted over several times with Spanish red, which tends to prevent the metal from melting. The metal must not be used too hot, otherwise it will melt the mold. By a little careful manipulation many pieces can be cast with these molds.

III.—New iron or brass molds must be blued before they can be used for casting purposes. This is done by placing the mold face downward on a charcoal fire, or by swabbing with sulphuric acid, then placing over a gas flame or charcoal fire until the mold is perfectly oxidized.