Cooley's Cyclopaedia of Practical Receipts Volume I Part 92

[Ill.u.s.tration: 2.]

The base or concrete must be perfectly dry when the mastic is poured on, or the work will be a failure, for the moisture will be converted into steam, which, issuing through the fluid mastic, will cause the formation of holes in the latter or blister it, and ultimately the surface will crack. To counteract in some measure the evil arising from the formation of steam, fine cinder dust is sifted over the bed of concrete previous to the application of the mastic.

When asphalting suspension bridges, a sheet of canvas is usually spread over the concrete.

In asphalting damp places, such as cellars and foundations, a brick invert is always laid in asphalt beneath the concrete. This is done by placing the bricks in rows, at the proper depth and slope, and pouring a coating of asphalt about a quarter of an inch thick upon them. Before the mastic solidifies, the bricks are separated a little by pa.s.sing a knife between them, thus affording the mastic an opening by which to seal up more thoroughly the connection. The concrete is afterwards laid upon this bed, and the layer of mastic upon this in the usual way. The thickness of the layer of mastic varies according to the attrition to which it is to be subjected; but the usual depth is from a quarter to one and a quarter inch.

_Artificial Asphalt._ This is prepared from coal tar by distilling off the volatile oils which hold the tar in solution, the result being that a kind of fatty pitch is left, which must be boiled until a sample, when cooled, becomes nearly solid. The operation may be accomplished in the open air, but if this means of evaporation be adopted, the process is attended with a very unpleasant odour, and the volatile oils are dissipated. These volatile oils are used for the preparation of varnish, for lubricating machinery, and for the manufacture of a superior kind of lampblack. They have also been employed to increase the illuminating power of coal-gas, which purpose they accomplish by imparting their vapours to gas pa.s.sed over them when they are placed in shallow vessels. Various forms of patent apparatus have been designed for this purpose.

When it is required to collect the oils, the coal tar is placed in a retort made of sheet iron, with a convex bottom, which is placed immediately over a fire. The products of the combustion after striking the bottom of the retort circulate round it, then proceed under a second boiler to heat the tar contained in it, and from which the retort is replenished when necessary. This vessel, when three quarters full, contains nearly 24 _cwts._ of tar; it should be perfectly embedded in masonry; the capital itself by which the volatile products escape should be surrounded with materials that are bad conductors of heat, such as ashes. But for this precaution the volatile oils would become condensed, and fall back into the evaporating vessel.

The volatile oils are collected by being made to pa.s.s through a tube cooled by a current of water, this tube running in a direction the reverse of that pursued by the vapours, and terminating in a closed vessel, which acts as the receptacle for the oils. A tube branching from the boiler conducts the uncondensed products outside the building in which the distillation is conducted.

When the tar has been boiled sufficiently long to give it the requisite consistence, it is removed by means of a pipe into a third hemispherical boiler of cast-iron. To prepare the bituminous mastic directly from this fatty pitch, the latter is kept in a state of fusion, and chalk in sufficient quant.i.ty is then added. If the chalk be previously heated, ground to a coa.r.s.e powder, and sifted, the mixture is effected more rapidly and satisfactorily.

The asphalt becomes the more solid the greater the proportion of chalk added; on the other hand, it becomes less elastic and more brittle. The asphalt is moulded as follows:--A long table is covered with cast-iron plates, surrounded with a framework, which is subdivided into eight or ten equal compartments by means of rules of about six inches in height, introduced vertically into grooves formed at equal intervals in the long sides of the frame. The eight or ten moulds obtained by this means are coated internally with a paste composed of sixty parts of water and forty of chalk. This compound prevents the mastic adhering to the sides of the mould, and ensures its being easily detached.

Two barrels, or 9 _cwts._ of tar, lose by distillation one fourth of their weight, the loss consisting of 1 _cwt._ 3 _qrs._ 15 _lbs._ of volatile oils, and 1 _qr._ 13 _lbs._ of water.

Sometimes ground or fine sand enters into the composition of asphalt in proportions equal to the chalk; but in some cases only half as much sand as chalk is used.

In the manufacture of asphalt it is very important that the contents of the cauldron should be stirred during fusion, not only to prevent the tar adhering to the bottom, and so getting burnt, but to ensure the ingredients being brought into intimate combination, and a h.o.m.ogeneous and smooth compound being produced.

As soon as the whole is thoroughly incorporated, the proper consistence attained, and the vapours of the volatile oils and water come off in very minute quant.i.ties, the asphalt is run off into the moulds before described, and when sufficiently set may be removed, and is ready for use.

Dr G. H. Smith has patented a process for making artificial asphalt, waterproof concrete, &c., which promises to become of great value in the construction of sea walls, docks, and harbour works, &c. Dr Smith's invention consists in filling up the interstices of any porous substance, such as brick, burned or unburned clay, soft stones, plaster of Paris, &c., with pitch or tar which has been boiled to such a consistence that the pores or cells of the material used are completely filled with solid matter when cold.

Other hydrocarbons, resins, or gums may be used instead of pitch or tar; but it is essential that the saturating substances, though naturally fluid or semifluid, can be so changed by boiling that they lose their fluidity when cold; or they must be, though hard under all ordinary temperatures of the atmosphere, capable of reduction by heat or otherwise to a fluid condition, so that they will penetrate the porous materials.

The asphalto-bitumen mine of the Val de Travers, in the Canton of Neufchatel, is said to be the richest and most extensive in the world of its particular cla.s.s. The calcareous bitumen which it yields contains 20% of nearly pure bitumen, and 80% of carbonate of lime; and it has a sp. gr.

(2115) approaching that of ordinary bricks.

The 'Val de Travers Company,' and the 'Bastenne and Gaujac Company,' are, it is said, those which have hitherto been the most successful in laying down asphalto-pavements. See ASPHALTUM, PETROLEUM, &c.

=Bitumen, Elastic.= _Syn._ MIN'ERAL CAOU'TCHOUC (koo'-chook), EL'ATERITE.

A rather rare species of bitumen, differing chiefly from the other solid varieties in being elastic.

=Bitumen, Liq'uid.= Petroleum.

=BITU'MINOUS.= _Syn._ BITUTMINO'SUS, L.; BITUMINEUX, Fr.; ERDPECHIG, Ger.

Of bitumen, or resembling or containing it.

=BIX'EINE= (-e-in). The red colouring-principle of annotta. It is obtained by treating bixine with liquid ammonia, with subsequent free contact of air.

_Prop., &c._ When pure, a rich deep-red powder, soluble in alcohol and in alkalies, and turned blue by sulphuric acid. It appears to be oxidised bixine.

=BIXIN.= The red resinous colouring matter of annatto. Bolley and Mylius prepare it by digesting the dried alcoholic extract of annatto with ether; repeatedly treating the least soluble portion (which contains the greater part of the colouring matter) with hot ether; dissolving the remainder in alcohol; precipitating the alcoholic solution with lead acetate; decomposing the washed precipitate with sulphuretted hydrogen; extracting the colouring matter therefrom by hot alcohol; and precipitating the alcoholic solution with water.

=BIX'INE= (-in). The yellow colouring-principle of annotta.

_Prep._ A solution of annotta is precipitated with a solution of acetate of lead; the precipitate, after having been washed in cold water, is decomposed by sulphuretted hydrogen; the decanted liquor or filtrate yields crystals by cautious evaporation.

_Prop., &c._ Yellowish white, turning full yellow by exposure to air; soluble in water, and freely so in alcohol and in alkaline solutions; by oxidation it is converted into bixeine. For a correct knowledge of both of these substances we are indebted to M. Preisser.

=BLACK.= _Syn._ A'TER,[189] NI'GER, L.; NOIR, Fr.; SCHWARZ, Ger.; BLAC, BLaeC, Sax. In _dyeing_, &c., of the colour of lamp-soot, or of night; subst., a black colour.

[Footnote 189: Black, deep black; as opposed to _albus_, white.]

=Black Ash.= The waste lye of the soapmakers is evaporated in large iron boilers, the salt separated as it falls down, and then heated in a reverberatory furnace, until it is partially decomposed and fused, when it is run into iron pots to cool. It is used in the manufacture of alum and common soap.

=Black Col'ours= (kul'-). See BLACK PIGMENTS.

=Black Draught.= See MIXTURE, SENNA (Compound).

=Black Drop.= See DROPS, PATENT MEDICINES, &c.

=BLACK DYE.= _Syn._ TEINTE NOIRE, Fr.; SCHWARZE FARBE, Ger. The following are the processes and materials now commonly employed in dyeing black:--

_a._ For COTTON:--

1. The goods, previously dyed blue, are steeped for about 24 hours in a decoction of gall-nuts or sumach, then drained, rinsed in water, and pa.s.sed through a bath of acetate of iron for a quarter of an hour; they are next again rinsed in water, and exposed for some time to the air; after which they are pa.s.sed a second time through the bath, to which a little more iron-liquor is previously added. The whole process is repeated, if necessary, according to the intensity of the shade of black desired.

2. The goods are steeped in a mordant of acetate of iron, worked well, and then pa.s.sed through a bath of madder and logwood for 2 hours. Less permanent than No. 1.

_Obs._ About 2 _oz._ of coa.r.s.ely powdered galls, or 4 _oz._ of sumach, are required for every pound of cotton, in the process of galling. The first should be boiled in the water, in the proportion of about 1/2 gal. of water to every lb. of cotton. The sumach-bath is better made by mere infusion of that dye-stuff in very hot water.

3. (For 10 lbs. of cloth.) The goods are put into a boiling bath made of 3 lbs. of sumach, and allowed to steep, with occasional 'working,' until the liquor is perfectly cold; they are next pa.s.sed through lime water, and, after having drained for a few minutes, immediately transferred to and worked for an hour in a warm solution of 2 lbs. of copperas; after free exposure to the air for about an hour they are again pa.s.sed through lime water, and, after draining, 'worked' for an hour in a bath made with 3 lbs. of logwood, and 1 lb. of fustic; they are then 'lifted,' and 1/4 lb.

of copperas being added, they are returned to the bath, 'worked' well for about 30 minutes, and finished. Good and deep.

_Obs._ Instead of copperas iron-liquor may be used, observing to take 1-1/2 pint of the latter (of the ordinary strength) for every lb. of the former ordered above.

_b._ For FLAX and LINEN:--

This, for the most part, closely resembles that employed for cotton; but, in some cases, a mordant of iron-liquor, or of copperas, followed by pa.s.sing the goods through lime-water, and exposure to the air, precedes the dye-bath.

_c._ For SILK:--

Silk goods are dyed much in the same way as woollens, but the process is conducted with less heat:--

1. A bath of nut-galls is given for 12 to 36 hours, occasionally working the goods therein; they are next taken out, rinsed, and well aired, after which they are pa.s.sed for a few minutes through a bath containing sulphate of iron, and are then again drained, rinsed, and aired. The steep in the nut-gall bath may be repeated, if necessary, followed, as before, by the iron-bath previously replenished with a little fresh copperas. The whole quant.i.ty of galls to be taken for 1 lb. of silk varies with their quant.i.ty from 1/2 to 3/4 lb., that of the copperas (for the first bath), from 3 to 4 _oz._

2. (For 1 cwt. of silk.) Boil 22 _lbs._ of bruised Aleppo galls, for 2 hours, in 90 to 100 galls. of water, observing to add boiling water from time to time, to compensate for that lost by evaporation; to the clear bath add 32 lbs. of copperas, 7 lbs. of iron-filings, and 21 lbs. of gum; digest with agitation for 1 hour, and when the ingredients are dissolved, pa.s.s the silk (previously prepared ['galled'] with 1/3rd of its weight of gall-nuts) through the bath for about an hour; then rinse and air it well; next leave it in the dye-bath for 6 to 12 hours; and this immersion or steep may be repeated, if necessary, at will. This is said to be the process commonly adopted for velvet at Genoa and Tours.

3. (For 5 lbs. of silk.) Turn the goods for an hour through a mordant formed of 1 lb. of copperas and 2 oz. of nitrate of iron (dyer's), with sufficient water; after rinsing in cold water and airing them, 'work' them for an hour in a decoction made of 5 lbs. of logwood and 1 lb. of fustic; then lift them from the bath, add 2 oz. of copperas, reimmerse, and 'work'

them well for 10 or 15 minutes longer; lastly, rinse, air, and finish. A full deep black.

4. (For 5 lbs.) For the mordant use 1/2 lb. of copperas; rinse, and air; for the 'dye-bath,' a decoction of 4 lbs. of logwood to which 1/2 pint of stale urine has been added; after 'lifting' the goods add 2 _oz._ more of copperas to the bath, and work for 15 minutes, as before. A good black. By adding 2 _oz._ of dyer's nitrate of iron to the mordant the same ingredients will give a deep black; and by subst.i.tuting a little white soap for the urine, and omitting the addition of copperas to the logwood-bath, it will give a blue-black. The last may also be produced by first dyeing the goods deep blue as with 'prussiate,' and omitting the urine and soap, in which case one half only of the logwood will be required.