Part 98

=Cement, French.= Mucilage of gum Arabic, thickened with starch powder or farina; a little lemon-juice is sometimes added. Used by naturalists in mounting specimens; by artificial-flower makers; and by confectioners, to stick paper, wafer papers, ornaments, &c., on their fancy cakes. Plain mucilage is often used in the same way.

=Cement, Gad's.= _Syn._ GAD'S HYDRAULIC CEMENT. From clay (well dried and powdered), 3 parts; oxide of iron, 1 part; mixed together, and made into a stiff paste with boiled oil. Used for work required to harden under water.

=Cement, Glass.= _Syn._ GLASS FLUX. _Prep._ Red lead, 3 parts; fine white sand, 2 parts; crystallised boracic acid, 3 parts; mixed and fused; it is levigated, and applied with thin mucilage of tragacanth. Used for mending broken china, &c. The repaired article must be gently heated, so as partially to fuse the cement.

=Cement, Gibbs'.= Mr Gibbs patented in 1850 various processes for making admirable building and architectural cements, equal in hardness and duration, and superior in colour, to the best Roman and Portland cements at present in use. His materials are obtained from "the vast beds of (natural) argillaceous marls and marly limestones, or marl stones, which contain the due admixture of lime, silica, and alumina, from which hydraulic cements and artificial stones may be manufactured." These materials he finds in "the chalk formation, the Wealden formation, the Purbeck beds, the lias formation, the mountain limestone, and the lowest strata of the coal-measures." After duly choosing his materials according to the particular object in view, he prepares them "by burning in kilns, and grinding in mills, in the way cement is now manufactured." Marls and limestones are to be "first dried in kilns or ovens, at a heat fit for baking, until all moisture be driven off, and that then the calcination be prolonged as much as possible; the heat being kept as low as is only just sufficient to effect complete calcination--this being indispensable, to avoid the commencement of vitrification, which would destroy the adhesive properties of the cement."

=Cement, Glue.= _Prep._ 1. From glue, 1 lb. melted with the least possible quantity of water, and then mixed with black resin, 1 lb., and red ochre, 4 oz.

2. Glue, melted as above, and mixed with about 1/4th of its weight each of boiled oil and red ochre.

3. (Ure.) Melted glue (of the consistence used by carpenters), 8 parts; linseed oil, boiled to varnish with litharge, 4 parts; incorporate thoroughly together.

4. Glue (melted as last), 4 parts; Venice turpentine, 1 part.

_Obs._ The first three dry in about 48 hours, and are very useful to render the joints of wooden casks, cisterns, &c., watertight; also to fix stones in frames. The last serves to cement glass, wood, and even metal to each other. A good cement for fixing wood to glass may be made by dissolving isinglass in acetic acid, in such quantities that it becomes solid when cold. When applied let it be heated. They all resist moisture well.

=Cement, Grind'ers'.= _Prep._ 1. From pitch, 5 parts; wood ashes and hard tallow, of each 1 part; melted together.

2. Black resin, 4 lbs.; beeswax, 1 lb. melt, and add of whiting (previously heated red hot, and still warm), 1 lb.

3. Shell-lac, melted and applied to the pieces slightly heated. Used to fix pieces of glass, &c., whilst grinding. The last is used for lenses and fine work.

=Cement, Hamelin's.= _Syn._ HAMELIN'S MASTIC. From siliceous sand, 60 parts; Bath or Portland stone (in fine powder), 40 parts; lime-marl, 20 parts; litharge, 8 parts; ground together. For use it is mixed up with linseed oil and used like mortar. When this cement is applied to the purpose of covering buildings intended to resemble stone, the surface of the building is first washed with linseed oil.

=Cement, Hensler's.= Litharge, 3 parts; quick-lime, 2 parts; white bole, 1 part (all in fine powder); linseed-oil varnish, q. s. to make a paste. Used for china, glass, &c. It is very tenacious, but long in drying.

=Cement, H[oe]nle's.= Shell-lac, 2 parts; Venice turpentine, 1 part; fused together, and formed into sticks. It is used like extemporaneous cement for glass and earthenware.

=Cement, Hydraulic.= Hydraulic mortars or cements are those which set or become hard under water. Common lime does not possess this property; but limestone containing from 8% to 25% of alumina, magnesia, and silica, yield a lime on burning, which does not slake when moistened with water, but forms a mortar with it, which hardens in a few days when covered with water, although it does not acquire much solidity in the air. Puzzolana, septaria, and argillaceous or siliceous earths, burnt, either with or without the addition of common limestone, and then ground to powder, form excellent hydraulic cements. The reniform limestone, commonly called "cement stone," which is found distributed in single nodules or lenticular cakes, in beds of clay, is the substance most commonly used in this country for the manufacture of the cements in question.

"A very good hydraulic mortar is made by slaking lime with water containing about 2 per cent. of gypsum, and adding a little sand to the product. The presence of the gypsum tends to delay the slaking of the lime, and also to harden the substance formed after the slaking.

"If water containing a little lime in solution be added to burnt gypsum, a very hard compact mass is obtained. This substance is much used as an imitation marble, as by polishing it with pumice stone, colouring it, and again polishing with oil, it may be made to resemble natural marble very closely. Hardened gypsum treated with stearic acid, or paraffin, and polished, is used as a substitute for meerschaum, which it much resembles."[238] See GAD'S, HAMELIN'S, and PARKER'S CEMENTS, &c.

[Footnote 238: 'Chemistry, Theoretical, Practical, and Analytical.']

=Cement, Iron.= This cement, which is much used for closing the joints of iron pipes and similar purposes, is formed of the borings or turnings of cast iron, which should be clean and free from rust, mixed with a small quantity of sal-ammoniac and flowers of sulphur. For use, it is stirred up with just enough water to thoroughly moisten it, and it is rammed or caulked into the joints with a blunt caulking chisel and hammer, after which the joint is screwed up by its bolts as tightly as possible. If the turnings and borings are very coarse they are broken by pounding in an iron mortar, and the dust sifted off before use. The following are good proportions:

1. Sal-ammoniac (in powder), 2 oz.; flowers of sulphur, 1 oz.; iron borings, 5 lbs.; water, q. s. to mix.

2. Sal-ammoniac, 2 oz.; sulphur, 1 oz.; iron borings, 12 lbs.; water, q. s. to mix.

3. Sal-ammoniac, 2 oz.; iron borings, 7 or 8 lbs.; water, q. s. to mix.

4. Iron borings, 4 lbs.; good pipeclay, 2 lbs.; powdered potsherds, 1 lb.; make them into a paste with salt and water.

_Remarks._ The first of these forms is that generally employed for common purposes, but formerly much more sulphur and sal-ammoniac were used. We are told by one of the leading engineers in London that the strongest cement is made without sulphur and with only 1 or 2 parts of sal-ammoniac to 100 of iron borings (see the third form); but that when the work is required to dry rapidly, as for the steam joints of machinery wanted in haste, the quantity of sal-ammoniac is increased a little, and a very small quantity of sulphur is added. This addition makes it set quicker, but reduces its strength. As the power of the cement depends on the oxidation and consequent expansion of the mass, it is evident that the less foreign matter introduced the better. No more of this cement should be made at a time than can be used at once, because it soon spoils. I have seen it become quite hot by standing even a few hours, when it contained sulphur; and I have been informed by workmen that when much sulphur is used, and it has been left together in quantity all night, combustion has taken place. The last form produces a cement that gets very hard when allowed to dry slowly, and is excellent for mending cracks in iron boilers, tanks, &c.

CEMENT, JAPANESE. _Syn._ RICE GLUE. From rice flour, mixed with a little cold water, and boiling water gradually poured in until it acquires a proper consistence; when it is boiled for 1 or 2 minutes in a clean saucepan or earthen pipkin. It is beautifully white, and almost transparent, for which reason it is well adapted for fancy paper work, which requires a strong and colourless cement. It is superior to French cement. (See _antè_.)

=Cement, Keene's Marble.= Baked gypsum or plaster of Paris, steeped in a saturated solution of alum, and then recalcined, and reduced to powder. For use it is mixed up with water, as ordinary plaster of Paris.

_Obs._ This cement has been most extensively applied as a stucco. It is susceptible of a high polish, and when coloured produces beautiful imitations of mosaic and other inlaid marbles, scagliola, &c. It is not adapted to hydraulic purposes, or for exposure to the weather, but it is admirable for internal decorations, and from its extreme hardness is very durable. It may be coloured or tinted of any shade, by diffusing mineral colours (levigated, if in powder) through the water used to mix up the cement with. A pleasing tint is given to this cement by adding a little solution of green copperas to the alum liquor.

=Cement, Laboratory.= _Syn._ CHEMICAL MASTIC. From equal parts of pitch, resin, and plaster of Paris (thoroughly dried), mixed together. Used for the masonry of chlorine chambers, vitriol works, &c.; and as a lining for casks intended to hold chloride of lime.

=Cement, Letter-fixing.= _Prep._ Copal varnish, 15 parts; drying oil, 5 parts; turpentine, 3 parts; oil of turpentine, 2 parts; liquefied glue (made with the least possible quantity of water), 5 parts; melt together in a water bath, and add fresh slaked lime (perfectly dry, and in very fine powder), 10 parts. Used to attach metal letters to plate glass in shop windows, &c.

=Cement, Mahogany.= _Prep._ 1. Melt beeswax, 4 oz.; then add Indian red, 1 oz., and enough yellow ochre to produce the required tint.

2. Shell-lac, melted and coloured as above. Very hard. Both are used to fill up holes and cracks in mahogany furniture by the cabinet makers. Red putty is also used for the same purpose.

=Cement, Maissiat's.= India rubber is melted either with or without about 15% of either beeswax or tallow; quick-lime (in fine powder) is gradually added; and the heat continued until change of odour shows that combination has taken place, and until a proper consistence is obtained. Used as a waterproof and air-tight covering for corks, bungs, &c.

=Cement, Marine.= See GLUE, MARINE, and CEMENT, ELASTIC.

=Cement, Martin's.= This is manufactured in the same way as Keene's, only carbonate of soda or carbonate of potash is used as well as alum, and the burning is carried on at a higher temperature.

=Cement, Opticians'.= _Prep._ 1. Shell-lac softened with rectified spirit or wood naphtha. For fine work.

2. Beeswax, 1 oz.; resin, 15 oz.; melt and add whiting (previously made red hot, and still warm), 4 oz.

3. Resin, 1 lb.; melt and add plaster of Paris (dry), 4 oz. The above are used to fix glasses, stones, &c., while polishing and cutting them. The last is a very strong cement for rough purposes.

=Cement, Oxychlo''ride of Zinc.= (Sorel.) _Prep._ In solution of chloride of zinc, marking from 50° to 60° of Baumé's hydrometer (_i.e._ sp. gr. 1·490 to 1·652), dissolve 3% of borax or sal-ammoniac; then add oxide of zinc which has been heated to redness, until the mass is of a proper consistence.

_Obs._ This cement becomes as hard as marble. It may be cast in moulds like plaster of Paris, or used in mosaic work, &c.

=Cement, Parabol'ic.= _Syn._ UNIVERSAL CEMENT. _Prep._ Curdle skim milk with rennet or vinegar, press out the whey, and dry the curd by a very gentle heat, but as quickly as possible. When it has become quite dry grind it in a coffee or pepper mill, and next triturate it in a mortar until reduced to a very fine powder. Mix this powder with 1/10th of its weight of new dry quick-lime, also in very fine powder, and to every ounce of the mixture add 5 or 6 gr. of powdered camphor; triturate the whole well together, and keep it in wide-mouth 1-oz. phials, well corked. Used to join glass, earthenware, &c. It is made into a paste with a little water, as wanted, and applied immediately.

=Cement, Parian.= Is prepared as Keene's, substituting a solution of borax (1 part of borax to 9 of water) for a solution of alum.

=Cement, Park'er's.= This cement is made of the nodules of indurated and slightly ferruginous marl, called by mineralogists "septaria," and also of some other species of argillaceous limestone. These are burnt in conical kilns, with pit coal, in a similar way to other limestone, care being taken to avoid the use of too much heat, as if the pieces undergo the slightest degree of fusion, even on the surface, they will be unfit to form the cement. After being properly roasted the calx is reduced to a very fine powder by grinding, and immediately packed in barrels, to keep it from the air and moisture.

_Uses, &c._ This cement is tempered with water, and applied at once, as it soon hardens, and will not bear being again softened down with water. For foundations and cornices exposed to the weather it is usually mixed with an equal quantity of clean angular sand; for use as a common mortar, with about twice as much sand; for coating walls exposed to cold and wet, the common proportions are 3 of sand to 2 of cement, and for walls exposed to extreme dryness or heat, about 2-1/2 or 3 of sand to 1 of cement; for facing cistern work, water frontages, &c., nothing but cement and water should be employed. Under the name of compo' or Roman cement it is much employed for facing houses, water cisterns, setting the foundations of large edifices, &c.

=Cement, Pew's.= Quick-lime, 1 part; baked clay, 2 parts (both in powder); mix and calcine; then add gypsum (fresh baked and in fine powder), 1 part, to powdered baked clay, 2 parts; mix well, add the former mixture, and incorporate them well together. Used to cover buildings. It is applied like mortar, and is very hard and durable. See CEMENT, GIBBS,' &c.

=Cement, Plumb'ers'.= Black resin melted with about an equal weight of brick-dust. Some times a little pitch or tallow is added.

=Cement, Port'land.= From clay and chalk, or argillaceous river-mud and chalk or limestone, calcined together, and then ground to powder. See CEMENT, PARKER'S.

=Cement, Ro'man.= Genuine Roman cement consists of puzzolene (a ferruginous clay from Pozzuoli, calcined by the fires of Vesuvius), lime, and sand. The only preparation which the puzzolene undergoes is that of pounding and sifting. It is generally mixed up with water, like most other cements, but occasionally with bullock's blood and oil, to give the composition more tenacity. That used in this country is now generally prepared from the septaria of either Harwich or Sheppy, or of the lias formation, or from the cement stone found in the upper division of the lias formation, or in the shale beds of the Kimmeridge clay. It is also prepared from several artificial mixtures of ferruginous clay and lime, calcined together. It must be kept in close vessels, and mixed with water when used. See CEMENT, PARKER'S and GIBBS'.

=Cement, Seal Engra''vers'.= Resembles plumbers' cement. Used to fix the pieces of metal while cutting, and also to secure seals and tools in their handles. It grows harder and improves every time it is melted.

=Cement, Sin'ger's.= _Prep._ 1. Melt together resin, 5 lbs., and beeswax, 1 lb., and stir in finely-powdered red ochre (highly dried and still warm), 1 lb., and plaster of Paris, 4 oz.; continuing the heat a little above 212° Fahr., and stirring constantly till all frothing ceases.

2. Resin, 6 lbs.; dried red-ochre, 1 lb.; calcined plaster of Paris, 1/2 lb.; linseed oil, 1/4 lb. Used to cement the plates in voltaic troughs, to join chemical vessels, &c. No. 2 is specially applicable to troughs. See CEMENT, ELECTRICAL.

=Cement, Steam-boiler.= _Prep._ Litharge, in fine powder, 2 parts; very fine sand and quick-lime (that has been allowed to slake spontaneously in a damp place), of each 1 part; mix and keep it from the air. Used to mend the cracks in boilers and ovens, and to secure steam joints. It is made into a paste with boiled oil before application.

=Cement, Steam-pipe.= _Prep._ Good linseed oil varnish is ground with equal weights of white lead, oxide of manganese, and pipeclay.

=Cement, Stucco.= This is a compound of powdered gypsum or strong gelatin. It is used for coating walls, and also for ornamenting ceilings. It takes a high polish, and coloured designs can be painted on it. When employed on walls a coarser kind is first laid on, which is followed by a coating made of choicer specimens of gypsum, or glue, or isinglass. When this latter and outer coat becomes dry it is polished with pumice, tripoli, and linen. The colour is incorporated with the outer coatings of the stucco by mixing the metallic pigments with it, and then applying it to the wall, after which a very thin coating of gypsum and isinglass, or sometimes of oil, is given to it, and when the whole is partially dried the tint is brought out by polishing, as before stated. Generally the finest effect is obtained by oil.

=Cement, Transpar'ent.= See CEMENT, ELASTIC.

=Cement, Turn'ers'.= _Prep._ Beeswax, 1 oz.; resin, 1/2 oz.; pitch, 1/2 oz.; melt, and stir in fine brickdust, q. s.

=Cement, Univers'al.= See CEMENT, PARABOLIC.

=Cement, Var'ley's.= _Syn._ VARLEY'S MASTIC. Black resin, 16 parts; beeswax, 1 part; melt, add whiting (sifted, dried by a dull-red heat, and allowed to cool), 16 parts; and stir until nearly cold.

=Cement, Water.= _Prep._ 1. From good grey clay, 4 parts; black oxide of manganese, 6 parts; limestone (reduced to powder by sprinkling it with water), 90 parts; mix, calcine, and powder.

2. Mix white iron ore (manganese iron ore), 15 parts, with lime, 85 parts; calcine and powder as above. Both this and the preceding must be mixed up with a little sand for use. A piece thrown into water rapidly hardens.

3. Fine clean sand, 1 cwt.; quick-lime, in powder, 28 lbs.; bone ashes, 14 lbs. The above are beat up with water for use. See CEMENT, HYDRAULIC, &c.

=Cement, Waterglass.= For glass, earthenware, porcelain, and all kinds of stoneware, these cements are excellent. A cement for glass and marble is prepared by rubbing together one part of fine pulverised glass, and two parts of pulverised fluorspar, and then adding enough waterglass solution to give it the consistency necessary in a cement.

Waterglass mixed with hydraulic cement to a thick dough makes a good cement for the edges and joints of stone and marble slabs. It is well to mix but little at a time, as it hardens very quickly. ('Journal of Applied Chemistry.')

=Cement, Wa'terproof.= Several compounds of this class have been already noticed. The celebrated "waterproof cement of Dihl" consists of porcelain clay or pipeclay, dried by a gentle heat, and powdered, mixed up to the consistence of a paste with boiled linseed oil, and, sometimes, a little oil of turpentine. It is coloured by adding a little red or yellow ochre, or any similar pigment. It is used to cover the fronts of buildings, roofs of verandahs, &c.

_Concluding Remarks._ For mending broken CHINA, EARTHENWARE, GLASS, and WOOD, the preparations generally used are the cements described above as ARMENIAN, BOTANY BAY, CHEESE, CHINESE, CURD, EGG, EXTEMPORANEOUS, GLASS, GLUE, HENSLER'S, H[OE]NLE'S, MAHOGANY, and PARABOLIC. For SPAR, MARBLE, and similar materials, the ALABASTER CEMENT is specially adapted; the EGG and PARABOLIC CEMENTS will, however, answer the same purpose. For CLOTH, LEATHER, PAPER, CARD, and LIGHT FANCY WORK, the most suitable cements are the ELASTIC, CHINESE, FLOUR, FRENCH, and JAPANESE. The cements adapted for CHEMICAL and ELECTRICAL APPARATUS, and for SEALING BOTTLES, are also termed BOTTLE, BRIMSTONE, CAP, CHEMICAL, ELECTRICAL, LABORATORY, MAISSIAT'S, and VARLEY'S. The BUILDING and HYDRAULIC CEMENTS are described under the heads ARCHITECTURAL, BEALE'S, BRUYERE'S, FIREPROOF, GAD'S, GIBBS', HAMELIN'S, HYDRAULIC, KEENE'S, OXYCHLORIDE, PARKER'S, PEW'S, PORTLAND, ROMAN, WATER, and WATERPROOF. The cements used for METAL-WORK, &c., in different trades, are noticed under the heads COPPERSMITHS', CUTLERS', ENGINEERS', GRINDERS', IRON, LETTER-FIXING, OPTICIANS', PLUMBERS', SEAL-ENGRAVERS', STEAM-BOILER, STEAM-PIPE, and TURNER'S. See GLUE, LUTE, MORTAR, TOOTH-CEMENT, &c.

=CEMENTA'TION.= The process of imbedding a substance in, or covering it with, some powder or composition capable of acting on it when heated, and in this state exposing it to a red heat. Iron is converted into steel, and glass into Réaumur's porcelain, by cementation.

=CEN'TAURIN.= _Syn._ CENTAURIN'A. The bitter extractive matter of _Erythæa centaurium_, or common centaury. Combined with hydrochloric acid, it has been highly recommended as a febrifuge.

=CER'ASIN.= _Syn._ PRUN'INE. The insoluble portion of cherry-tree gum. It is identical with bassorin. Dr John applies the term to all those gums which, like tragacanth, swell, but do not dissolve in water. See BASSORIN.

=CE'RATE.= _Syn._ CERA'TUM, L. A thick species of ointment containing wax. Cerates are intermediate in consistence between ointments and plasters; but are less frequently employed than either of those preparations. The medicinal ingredients which enter into the cerates are very numerous; indeed, almost every kind of medicine capable of exercising a topical effect may be prescribed in this form.

It is a general custom with the druggists to use a less quantity of wax for their cerates than that which is necessary to give them a proper consistence, and in many cases it is omitted altogether, and its place supplied by hard suet, or stearine, and frequently by common resin. Lard is also very generally substituted for olive oil. Indeed, in no class of pharmaceutical preparations are the instructions of practitioners and the colleges more commonly disregarded. The operation of melting the ingredients should be performed in a water bath or steam bath, and the liquid mass should be assiduously stirred until cold.

All the medicated cerates may be prepared by adding the active ingredients, in the form of fine powder, soft extract, solution, &c., as the case may be, to either simple cerate or spermaceti cerate, in the proportions indicated under the head of "Doses" appended to every article of importance noticed in this work. The mixture, which must be complete, may be effected by working the articles together on a marble or glass slab or tile, or, still better, by trituration in a clean wedgwood mortar. In some cases the simple cerate is melted by a gentle heat, and the whole stirred or triturated until nearly solid; in others, digestion with heat is employed.

=Cerate.= _Syn._ SIM'PLE CERATE, SIMPLE DRES'SING; CERATUM (Ph. L.), C. SIM'PLEX (Ph. L. 1824). _Prep._ (Ph. L.) Yellow wax, 20 oz.; melt by a gentle heat; add olive oil, 1 pint; and stir until it begins to solidify.

Used as a simple emollient dressing. The corresponding preparations of the other colleges will be found noticed under OINTMENTS. The _ceratum simplex_ of the Ph. E. is SPERMACETI CERATE.

=Cerate, Ac'etate of Lead.= _Syn._ CE'RATE OF SUGAR OF LEAD; CERA'TUM PLUM'BI ACETA'TIS (Ph. L.), L. _Prep._ (Ph. L.) White wax, 5 oz.; olive oil, 18 fl. oz.; melt together; add, acetate of lead (in fine powder), 5 dr., previously triturated with olive oil, 2 fl. oz., and stir till they unite (begin to solidify). Used as a cooling dressing to burns, excoriations, and inflamed sores.