Cooley's Cyclopaedia of Practical Receipts Volume Ii Part 20

Jablochkoff's system is also in work in Paris in front of many public buildings, and by its means the Place and Avenue de l'Opera, together occupying a s.p.a.ce 900 yards long by 30 wide, are brilliantly illuminated every night.

That celebrated circus, so well known to every visitor to Paris, the Hippodrome, is also lighted by it.

Another form of electric lamp is that of M. Rapieff, now in use in the machine-room of the 'Times' newspaper office. In this lamp there are four carbon points instead of two. M. Rapieff, like M. Jablochkoff, states that by means of his system he is enabled to supply several lamps with the same electric current. In the Wallace-Farmer lamp slabs of carbon instead of points are had recourse to.

In the lamps of M. Regnier in one variety two revolving carbon discs are used, whilst in another a rod of carbon descends upon a disc of the same material, an arrangement which the inventor states leads to the subdivision of the current and its separate utilisation by a number of such lights.

One of the latest and apparently most successful methods for dividing the electric current, so that one and the same current shall be made simultaneously to supply and render incandescent a series of carbon points, and in so doing give rise to as many effective electric illuminators, is that of Mr Werdermann. Mr Werdermann, observing the disparity of consumption between the positive and negative poles of the electrodes, found by experiment that when the sectional area of the negative pole was sixty-four times greater than the positive one, the electric arc was so far reduced, that the two carbons were in contact.

Under these conditions the electric arc was infinitely small, the negative electrode was not consumed, whilst the positive one was incandescent. Two supplies of electric light, therefore, ensued, one by the electric arc, and the other by the incandescent carbon of the positive electrode. Under these circ.u.mstances, if it were possible to devise a plan by which the positive pole as it consumed should be kept in uniform contact with the negative pole, the difficulty which had hitherto proved the stumbling-block to using a series of lights from one current would be annihilated.

Mr Werdermann demonstrated the correctness of his premises by a practical ill.u.s.tration of his plan very lately (November, 1878) at the British Telegraph Manufactory, 374, Euston Road. The current from a dynamo-electric Gramme machine of 2-horse power was conducted to two electric lamps, each having an illuminating value equal to 360 candles each. The light so produced is described by a spectator as "being soft and sun-like, and as being capable of being looked at without discomfort, though it was not shaded." These being extinguished, ten smaller lamps were ignited by means of the same current, each one having an illuminating power equal to forty candles. "The lamps burned steadily with a beautiful soft and clear white light. First one of the ten lights was then extinguished, and afterwards a second, the only effect on the remainder being that they became slightly more brilliant."[15]

[Footnote 15: 'Daily News.']

Unlike Mr Edison, Mr Werdermann does not believe in the indefinite divisibility of the electric light. It will be observed that the candle power of the light becomes diminished by subdivision. Two lights gave a light equal to 700 candles, whereas the same current divided into ten lights gave an aggregate light of only 400 candles.

The following extract from the 'Times' of December 5th, 1878, ill.u.s.trates the financial aspect of the electric light question:--

"At the usual weekly meeting of the Society of Arts, held last evening, Dr C. W. Siemens, F.R.S., in the chair, a paper on electric lighting was read by Mr J. N. Shoolbred, M. Inst. C.E. The object of the author was to present some results of the application of electric lighting to industrial purposes, especially as regards cost. He noticed first the Holmes and the Alliance magneto-electric machines, giving alternating currents and single lights for lighthouse use. Secondly, he referred to the dynamo-electric machines, producing single lights for general industrial purposes, as well as for lighthouses, and including the Siemens and the Gramme machines. In his third group the author included the machines used for producing divided lights, each group indicating a marked period representing a clearly defined stage of progress in electric lighting. With regard to cost, Mr Shoolbred stated that in every instance his figures and particulars were those afforded by the users of the various lights, and not by the inventors or their representatives. In the case of the Holmes machine the annual cost per lighthouse was about 1035, inclusive of interest, repairs, and wages. With the Siemens machine the annual cost was about 494 per lighthouse, including interest and the other expenses. With the Alliance machine as used at Havre the cost was about 474 per annum per lighthouse, interest, &c., included. The single-light Gramme machine has been in use in the Paris goods station of the Northern of France Railway for two years. Six machines have been kept going with one light each, and the cost is found to be 5_d._ per light per hour, or with interest on outlay at 10 per cent., 8_d._ per hour. The same light at the ironworks of Messrs Powell at Rouen was stated to cost 4_d._ per light per hour, exclusive of interest and charge for motive power, the latter being derived from one of the engines on the works. In 1877 a series of experiments were carried out with the Lontin light at the Paris terminus of the Paris, Lyons, and Mediterranean Railway. The pa.s.senger station was lighted, and the results were so satisfactory that the company have entered into a permanent contract with the proprietors of the Lontin light for lighting their Paris goods station with 12 lights, at a cost of 5_d._ per light per hour. The Western of France Railway Company have had 6 Lontin lights in the goods station at the Paris terminus, St Lazare, since May last, and 12 lights in the pa.s.senger station since June. Careful experiments have shown the cost to be 8_d._ per light per hour, inclusive of interest. Referring to the Jablochkoff light, Mr Shoolbred placed before the meeting some particulars with regard to its application in the Avenue de l'Opera, Paris, which were afforded him by M. J. Allard, the chief engineer of the lighting department of the City of Paris. It appears that the authorities pay the Societe Generale d'electricite 37f. 2c. per hour for the 62 lamps in use there. These 62 lamps supersede 344 gas-jets which were previously used, and which cost the authorities 7244f. per hour. The electric illumination, however, is considered as equal to 682 gas-jets, or about double the original illumination--that is, to a cost of 1445f. per hour as against 372f. for the electric light, the cost of which, therefore, is 26 times that of the gas. The contract for lighting by electricity was terminated by the City of Paris on the 30th ult., and the authorities have declined to renew it except at the price paid for gas, namely, 7224f. (or about 6_s._) per hour, and that only until the 15th of January next. These terms have been accepted by the Societe, so that the price paid to them will be at the rate of about 1-1/8_d._ per light per hour. Mr Shoolbred stated that the Societe place their expenses at 106f. (or just 11_d._) per light per hour, which, however, they hope shortly to reduce by one half. A series of careful photometric experiments carried out by the munic.i.p.al authorities with the Jablochkoff lights, above referred to, showed each naked light to possess a maximum of 300 candles of intensity. With the gla.s.s globe this was reduced to 180 candles, showing a loss of 40 per cent., while during the darker periods through which the lights pa.s.sed the light was as low as 90 candles. The foregoing were the only authenticated particulars which the author could obtain as regards the working of the various electric systems of electric lighting. In conclusion, Mr Shoolbred referred to the Rapieff light at the 'Times' office, which, he observed, worked fairly and with regularity, which could not be said of all others, and it might therefore be ent.i.tled to take rank as an established application of electric illumination. The paper was ill.u.s.trated by the Siemens, Rapieff, Serrin, and other forms of electric light, which were shown in operation."

That the electric light is eventually destined to supplant coal gas in illuminating the fronts of large buildings, open s.p.a.ces, squares, a.s.sembly rooms, public halls, theatres, picture galleries, workshops and factories, &c., seems no very extravagant prediction. We have already seen that it has for some years been employed in one lighthouse; and we have the testimony of Mr Douglas, of the Trinity House, at a very recent meeting of the Society of Arts, that at the Souter Point Lighthouse there had been only two stoppages in eight years, once through a bad carbon breaking, and once through the lighthouse-keeper going to sleep.

In addition to places above specified, amongst other localities in which it is in work, we may mention the chocolate factories of M. Menier, at Noiselle, his india-rubber works at Grenelle, his sugar refinery at Nice, and Messrs Caille's works at Paris. In this country it was employed in the erection of the Tay Bridge, as well as in the works of Messrs Head, at Stockton-on-Tees, and in London it may be nightly seen burning before the Gaiety Theatre in the Strand, at Billingsgate Market, and frequently lighting up the front of the Stereoscopic Company's premises in Regent Street. Further, we may add that the Metropolitan Board of Works are making the experiment of lighting the Victoria Embankment and the City authorities the Holborn Viaduct, with the Jablochkoff candle. The former have placed a dynamo-electric apparatus, worked by a steam engine of 20-horse power, close to the foot of Hungerford Bridge, from whence wires will be carried right and left towards Westminster and Blackfriars respectively.

We believe the main conducting wire is carried under the coping-stone of the parapet running along the Embankment, and that the carbon points are fixed on the top of a certain number of gas standards which now surmount the wall of the Embankment.

That electricity is more economical as a method of artificial lighting than coal-gas the figures previously given seem to demonstrate, and there can be no question as to the much greater luminosity and purity of the light over the gas flame, qualities which render it an admirable subst.i.tute for the sunlight, the absence of which it may be said to supply at night. One disadvantage urged against its employment in weaving rooms is, that it casts such dark and distinct shadows that these are frequently mistaken for the threads themselves, an objection which is said to have been remedied by placing the light as near the ceiling as possible. The non-generation of carbonic acid and sulphurous products such as are given off by burning gas, although of slight importance when the light is employed in the open air, becomes a great advantage when it is used in crowded a.s.sembly rooms or theatres, since the atmospheric contamination caused by carbonic acid becomes of course considerably reduced. The absence of sulphur compounds especially qualifies the light for use in large libraries. If it be true that the light gives rise to an appreciable amount of ozone, this const.i.tutes another point in its favour. Opinion is at variance as to the possibility of the practical application of the electric light for illuminating private houses and dwellings in such a manner as to supply the place of the gas we now burn in them. One serious impediment to the probable accomplishment of this result certainly seems to be the fact that electricity for lighting purposes can only practically be conveyed to short distances from its source, which would necessitate the establishment and supervision of a number of generating machines near the houses to be lighted. Another obstacle, which hitherto has not been overcome, is the circ.u.mstance that the current when subdivided yields proportionately a greatly diminished amount of light. For instance, one light which had a certain photometric candle valve would yield when divided into two an aggregate amount of light considerably less than the one; and if divided into three still less, and so on. This has been pointed out when noticing Mr Werdermann's invention for the divisibility of the light. Mr Edison, an American inventor, a.s.serts that he has conquered this difficulty, and additionally perfected a machine for measuring the current used in the electric light. He states that it consists of an apparatus placed in every house lighted by electricity, which registers the quant.i.ty of electricity consumed, and uses for the purpose 1000th part of the quant.i.ty employed in the building.

Dr Siemens, no mean authority, doubts the practicability of applying electric lighting to household illumination.

A matter of primary importance in connection with the successful working of the electric light is the quality of the carbon points. In their manufacture gas carbon obtained from the necks of the retorts used in gas-making, as being the hardest and purest, is employed.

Superior, however, as this form of carbon is to every other description of the substance, it is never chemically pure, and as any foreign substance imparts to the light the irregularity or flickering that sometimes accompanies it, it is necessary the impurities should be removed. To effect their separation the carbon has to undergo several processes, such as soaking in caustic potash to remove the silica, treatment with strong acids, several was.h.i.+ngs, grinding, &c. It is then kneaded and put into moulds, in which it is subjected to a pressure as high as 12 tons to the square foot. Subsequently the points so made are baked.

=LIGHTNING.= See ACCIDENTS.

=LIG'NIN.= C_{6}H_{10}O_{5}. _Syn._ CELLULOSE. This is woody fibre deprived of all foreign matter. It forms about 95 per cent. of baked wood, and const.i.tutes the woody portion of all vegetable substances. Fine linen and cotton are almost entirely composed of lignin, the a.s.sociated vegetable principles having been removed by the treatment the fibres have been subjected to during the process of their manufacture.

Pure lignin is tasteless, inodorous, insoluble in water and alcohol, and absolutely innutritious; dilute acids and alkaline solutions scarcely affect it, even when hot; oil of vitriol converts it into dextrin or grape sugar, according to the mode of treatment. When concentrated sulphuric acid is added very gradually to about half its weight of lint, linen rag, or any similar substance shredded small, and contained in a gla.s.s vessel, with constant trituration, the fibres gradually swell up and disappear, without the disengagement of any gas, and a tenacious mucilage is formed, which is entirely soluble in water. If, after a few hours, the mixture be diluted with water, the acid neutralised by the addition of chalk, and, after filtration, any excess of lime thrown down by the cautious addition of a solution of oxalic acid, the liquid yields, after a second filtration, and the addition of alcohol in considerable excess, a gummy ma.s.s, which possesses all the characters of pure dextrin. If, instead of at once saturating the diluted acid solution with chalk, we boil it for 4 or 5 hours, the dextrin is entirely converted into grape sugar, which, by the addition of chalk and filtration, as before, and evaporation by a gentle heat to the consistence of a syrup, will, after repose for a few days, furnish a concrete ma.s.s of crystallised sugar. By strong pressure between folds of porous paper or linen, redissolving it in water, agitation with animal charcoal, and recrystallisation, brilliant colourless crystals of grape sugar may be obtained. Hemp, linen, or cotton, thus treated, yield fully their own weight of gum, and 1 per cent.

of their weight of grape sugar. During the above transformation, the sulphuric acid is converted into sulpholignic acid, and may be procured in a separate state. A solution of oxide of copper in ammonia, or solution of basic carbonate of copper in strong ammonia, dissolves cotton, which may then be precipitated by acids in colourless flakes.

=LIG'NITE.= _Syn._ BROWN COAL. Wood and other matter more or less mineralised and converted into coal. The lignites are generally dark brown, and of obvious woody structure. They are distinguished from true coals by burning with little flame and much smoke. Those of Germany are largely used as a source of paraffin and burning oils.

=LIG'NUM VI'Tae.= See GUAIAc.u.m WOOD.

=LIME.= CaO. _Syn._ OXIDE OF CALCIUM; CHAUX, Fr.; KALK, Ger. Lime, when pure, and as a chemical and medical reagent, will be found treated of under CALCIUM (Oxide of). It is prepared on the large scale for commerce by calcining chalk, marble or limestone, in kilns, and is called quicklime, caustic lime, burnt lime, stone lime, &c. The lime kilns are usually of the form of an inverted cone, and are packed with alternate layers of limestone and fuel, and the burnt lime raked out from the bottom. The lime thus obtained is a pale yellow powder, combining eagerly with water, and crumbling to a light white powder, "slaked lime," with the evolution of much heat. Lime which slakes well is termed "fat lime," while if it slakes badly is termed "poor lime." The slaked lime, the CALCIS HYDRAS of the B. P., is fresh lime sprinkled with water till it falls to powder.

=Lime, Salts of.= See under CALCIUM.

=Lime, Pyrolignite of.= An impure acetate of calcium used for making mordants in dyeing and calico printing, as a subst.i.tute for the more expensive acetate of lead.

=Lime, Chloride of.= _Syn._ BLEACHING POWDER, CHLORINATED LIME, HYPOCHLORITE OF CALCIUM.

This article was formerly believed to be a compound of lime and chlorine (CaO.Cl), and consequently received the name of 'chloride of lime.' We now know, however, that it is not a definite substance, but a mixture of calcium hypochlorite, calcium chloride, and calcium hydrate. The value of this preparation is due to the readiness with which the calcium hypochlorite is decomposed by acids, even by the carbonic acid of the air, with the evolution of hypochlorous acid which abstracts hydrogen from many vegetable colouring matters, badly smelling gases, &c.: the former are thereby bleached and the latter deodorised.

Chloride of lime is most extensively used for bleaching linen, calico, and similar fabrics, thousands of tons being made near Newcastle alone every year. It is also largely employed as a deodoriser.

_Prep._ Freshly slaked lime is thinly spread out in a proper vessel and exposed to an atmosphere of chlorine gas until it is saturated. Now included in the Materia Medica.

Slaked lime (fresh), 20 parts, common salt, 1 part, are mixed together, and the powder placed in long earthenware vessels into which chlorine is pa.s.sed until the mixture begins to grow damp, or until one part of it, dissolved in 130 parts of water, is capable of decolouring 4-1/2 parts of sulphate of indigo (see CHLORIMETRY), when the whole is transferred to dry bottles.

(Wholesale.) The chlorine is generated from the usual materials mixed in leaden vessels, heated by steam, and the gas, after pa.s.sing through water, is conveyed by a leaden tube into an apartment built of siliceous sandstone, and arranged with shelves or trays, containing dry fresh slaked lime, placed one above another, about an inch asunder. The process, to produce a first-cla.s.s article, is continued for 4 or 5 days. During this time the lime is occasionally agitated by means of iron rakes, the handles of which pa.s.s through boxes of lime placed in the walls of the chamber, which thus act as valves.

The successful manufacture of bleaching powder is dependent upon the careful observance of a number of conditions, such as the quality of the limestone,[16] which should be free from iron; the presence of magnesia at the time is also very objectionable, since it gives rise to the formation and presence in the bleaching powder of deliquescent chloride of magnesium; the apportionment of the water in slaking the lime is also a matter of no inconsiderable importance, the lime forming into b.a.l.l.s, which fail to properly absorb the gas if the water be insufficient, whilst if it be in excess, it yields a powder deficient in chlorine. When slaked, the lime is pa.s.sed through a sieve to free it from small pebbles. After being slaked it is kept for 2 or 3 days before being used, as it is found that under these circ.u.mstances it absorbs chlorine more readily than when recently prepared. Previous to its entrance into the lime chamber, the chlorine is pa.s.sed through water, to free it from vapour, and solid particles of chloride of manganese.

[Footnote 16: A very pure kind of limestone, and one which is largely used in the preparation of bleaching powder, is found at Buxton.]

The temperature of the chamber into which the chlorine is pa.s.sed ought not to exceed 62 F. An excess of chlorine has been found to yield a powder deficient in hypochlorite.

Bleaching powder, unless protected from the air (carbonic acid), slowly parts with its chlorine. In summer it has been estimated that it loses as much as 86 per cent. of the gas, and in winter about 26 per cent.

_Prop., &c._ Chloride of lime is a pale, yellowish-white powder, generally more or less damp, and evolving a chlorine-like odour of hypochlorous acid. Its soluble const.i.tuents dissolve in about 20 parts of water. It is decomposed by acids with the evolution of chlorine and oxygen (hypochlorous acid). Good chloride of lime should contain from 32% to 36% of chlorine, of which, however, but 25% to 30% can be easily liberated by an acid.

_Estim._ See CHLOROMETRY.

_Uses._ Chloride of lime is employed in medicine as a deodoriser and disinfectant. An ointment of chloride of lime has been used in scrofula, and a lotion or bath, moderately dilute, is one of the cleanest and readiest ways of removing the 'itch,' and several other skin diseases. It is also in great use as a disinfectant, and may be used either in substance or solution. A small quant.i.ty of the powder spread on a flat dish or plate, and placed on the chimney-piece, and a like quant.i.ty in an opposite part of the room, will continue to evolve sufficient chlorine or hypochlorous acid to disinfect (? Ed.) the air of an apartment for several days. The evolution of chlorine is promoted by occasionally renewing the exposed surface, by stirring it with a piece of stick, and after it becomes scentless, by the addition of a little acid, as strong vinegar, or hydrochloric acid, or oil of vitriol, largely diluted with water. Of late, however, it has been partly superseded by sulphurous acid, carbolic acid, &c. The most extensive consumption of chloride of lime is, however, for bleaching textile fabrics. When employed for this purpose, the goods are first immersed in a dilute solution of this substance, and then transferred to a vat containing dilute sulphuric acid. The chlorine thus disengaged in contact with the cloth, causes the destruction of the colouring matter. This process is generally repeated several times, it being unsafe to use strong solutions. White patterns may thus be imprinted upon coloured cloth; the figures being stamped with tartaric acid thickened with gum water, the stuff is immersed in the chloride bath, when the parts to which the acid has been applied remain unaltered, while the printed portions are bleached white.

_Concluding Remarks._--Chloride of lime is now scarcely ever made on the small scale, as it can be purchased of the large manufacturer of better quality and cheaper than it could possibly be made by the druggist. The chief precaution to be observed in the manufacture of good bleaching powder is to maintain the ingredients at a rather low temperature.

=LIME.= The fruit of _Citrus limetta_. It resembles the lemon, but is smaller and has a smoother skin. It is imported into Great Britain in a preserved state for use as a dessert. Its juice is also largely imported for the preparation of CITRIC ACID, and for the prevention of scurvy on board s.h.i.+p (see _below_).

=LIME JUICE.= _Syn._ LEMON JUICE. The juice of the fruits of various species of _Citrus_, princ.i.p.ally LIMES, is known in commerce under these names. It is very variable as to quality, which depends upon the method of extraction, the quality of the fruit, and the honesty of the s.h.i.+pper.

We have examined the juice expressed from limes sent from the West Indies, from Jamaica, and from South Africa, with the following results:

W. Indies. Jamaica. S. Africa.

Specific gravity of juice 104130 104418 104490 Per cent. of citric acid 796 866 850 Per cent. of ash 0321 0401 0364

The yield from limes is very small, and the freshly expressed juice contains a large amount of pulp. This, however, on standing a few weeks, separates, and a clear sherry-coloured liquid is obtained.

A concentrated lime or lemon juice is used by calico printers. It is a "dark, treacly-looking fluid, marking from 48 to 54 Twaddell," and contains about 30 per cent. of pure citric acid.

_Adult._ See LEMON JUICE.

_Estim._ Lime juice is only valuable on account of the citric acid it contains. If of good quality, 100 gr. will neutralise from 70 to 76 gr. of pure crystallised carbonate of soda. "For commercial purposes each grain of carbonate of soda neutralised may represent a half grain of crystallised citric acid (equal to 38 gr. of dry acid), and the value of the lime juice be calculated in proportion." (O'Neill.) As commercial lime juice contains variable proportions of vegetable extractive matter, the indications of the hydrometer cannot be depended upon. ACIDIMETRY, CITRIC ACID, &c.

=LIME'STONE.= A general term applied to a great variety of rocks in which carbonate of lime is the princ.i.p.al const.i.tuent.

_Estim._ The value of chalk, limestone, marble, &c., for hydraulic mortars and cements, may be determined as follows: