Chapter VII: Front Matter (7)

Leeches are best preserved in water obtained from a pond, and occasionally changed; when kept in spring water they soon die. The introduction of a hand to which an ill-flavoured medicine or odour adheres into the water in which they are kept is often sufficient to poison them. The application of saline matter to the skin of leeches, even in very small quantities, immediately occasions the expulsion of the contents of the stomach; hence a few grains of common salt are frequently sprinkled over them, to make them disgorge the blood which they have swallowed. The frequent changing of the water in which leeches are kept is injudicious. Once a month in winter, and once a week in summer, is deemed sufficiently often by the large dealers, unless the water becomes discoloured or bloody, when it should be changed every day, or every other day. When clean pond water cannot be obtained, clean rain water that has been well exposed to the air should alone be employed. Mr J. R. Kenworthy recommends placing in the water a few balls of irregular lumps of pure clay, about 2-1/2 inches in diameter; a method which we can recommend as both simple and successful. The plan adopted by M. Fée is as follows:——Place 7 inches of a mixture of moss, turf, and charcoal, in a marble or stone trough, over which sprinkle some small pebbles. At one end of the trough, and about half way up, place a thin shelf of stone or marble, pierced with small holes, on which put first some moss, or portions of marsh horse-tail (_Equisetum palustre_), and on this a layer of pebbles to keep it down; then pour in water sufficiently high just to moisten the moss and pebbles, put in the leeches, and tie over the mouth of the trough with a cloth. Another plan consists in keeping the leeches in a glass tank, or aquarium, provided with a pebbly bottom and a few healthy aquatic plants.

_Propag._ According to Dr Wagner, an annual feast on living blood is necessary to render leeches able to grow and propagate. These conditions can only be fulfilled by restoring to the breeding cisterns those which have been already employed. All artificial methods of feeding them by bladders or sponges of blood have been found to fail. He recommends the employment of two tanks, with the bottom formed of loam, clay, or turf, surrounded by an inner border of a similar substance, and an outer one of sand——the one for leeches fit for medical use——and the other for breeding, or for such leeches as have been applied. No leeches are to be taken from the breeding tank until a year has elapsed after their having been applied and fed with human blood; and their removal to the first tank should take place in September, or October, as by this time the breeding season is over. By this plan all leeches that have been applied are to be carefully restored to the breeding tank, without making them disgorge the blood they have swallowed.

=LEECH′ING.= This consists in the application of leeches to any vascular part of the body, for the purpose of withdrawing blood from it, and thus allaying local inflammation, distension of vessels, &c. Leeches are most conveniently applied by means of a common pill-box or a wine glass. The part should be previously washed perfectly clean, and if covered with hair should be closely shaved. Sometimes leeches are indisposed to bite; in such cases, allowing them to crawl over a piece of dry linen or calico, rolling them in porter, moistening the part with a little milk or sweetened milk, or drawing a little blood by a slight puncture or scratch, will usually make them bite freely. To stop the bleeding from leech-bites various plans are adopted, among which the application of nitrate of silver or creasote, or gentle pressure for some hours with the finger, are the most successful. Of late years a piece of matico leaf or soldier’s herb, applied in the same manner as a piece of lint, has been commonly adopted to stop the bleeding of leech-bites.

=LEEK.= _Syn._ PORRUM, L. The _Allium porrum_ (Linn.). Its general properties are intermediate between those of the onion and garlic. The juice is said to be powerfully diuretic, and capable of dissolving phosphate calculi.

=LEGU′MIN.= Vegetable casein. It is found most abundantly in the seeds of leguminous (podded) plants, _e.g._ beans, peas, &c., as well as in the sweet and bitter almond.

In properties it closely resembles the casein of milk.

Legumin may be obtained from peas or from almonds as follows:——After digesting the crushed seeds for 2 or 3 hours in warm water, the undissolved portion is removed by straining through linen, and the strained liquid, after depositing the starch suspended in it, is next filtered and mixed with diluted acetic acid. The white flocculent precipitate which is thus produced, is then collected on a filter and washed. It is afterwards dried, powdered, and digested, first in alcohol, and afterwards in ether.

Rochleder considered that, as thus obtained by Dumas and Cahours, it was not absolutely pure, since as it was not entirely soluble in a cold concentrated solution of potash, he recommended the alkaline solution being decanted from the undissolved portion, and again precipitated by the addition of acetic acid.

Legumin as thus prepared was believed by Rochleder to be pure, and was found on analysis to give results analogous to those furnished by casein.

In the seed, legumin occurs associated with considerable quantities of the phosphates of calcium, magnesium, and potassium. Rennet coagulates it like it does the casein of milk, its similarity to which is exemplified by the manufacture of a kind of cheese from peas and beans by the Chinese.

Dried peas contain about a fourth of their weight of legumin.

=LEM′ON.= _Syn._ LIMO, L. The fruit of the _Citrus limonum_ or lemon tree. The juice, peel, and essential oil are officinal. See OIL, and _below_.

=LEM′ON AC′ID.= See CITRIC ACID.

=LEM′ON FLA′VOUR.= See ESSENCE OF LEMON.

=LEM′ON JUICE.= _Syn._ LIMONIS SUCCUS (B. P.), SUCCUS LIMONUM (Ph. L. & D.), L. The juice of the lemon, obtained by squeezing and straining. When freshly expressed, it is turbid, owing to the presence of mucilage and extractive matter. These substances render the juice liable to decomposition, and various methods have from time to time been proposed for preserving it. Amongst these may be mentioned the addition to the fresh juice of one per cent. of bisulphite of calcium, or ten per cent. of proof spirit.

“We have examined the juice expressed from two varieties of lemons, viz. Palermo and Messina, with the following results:

Palermo. Messina.
“Ounces of juice yielded
by 100 lemons 108 96
Specific gravity of juice 1044·85 1038·56
Percentage of citric acid 8·12 7·04
Percentage of ash 0·289 0·301

“100 parts of the ash of the juice of Palermo lemons gave:

“Sulphuric acid 10·59
Carbonic acid 16·33
Chlorine 0·81
Phosphoric acid 6·74
Ferric phosphate 1·32
Lime 8·89
Magnesia 3·02
Potash 47·84
Soda 3·32
Silica 0·72
Loss 0·42
——————
100·00

“If lemons are kept a few months before squeezing, the yield of juice is slightly increased, but its specific gravity and percentage of citric acid remains unaltered. It is erroneous to suppose that the acid of the lemon is, by keeping, changed into sugar. We have kept lemons for 12 months, and found that the percentage of acid was not diminished. A certain proportion of sugar was formed, but at the expense of the soluble starch contained in the cell-walls of the lemon. Lemon juice on being kept is found to decrease in density, but the amount of acid remains the same.” (Harkness.)

Lemon juice may be preserved by heating it to 150° Fahr., filtering, and setting it aside in bottles completely filled. If this process be performed in the winter, the juice, it is said, may be kept perfectly good for 12 months. Fresh lemon juice is prevented from decomposition and rendered fit for exportation by mixing it with 1/10th of alcohol. (Schweitzer.)

The Merchant Shipping Act of 1867 requires that after a ship has been at sea ten days 1 oz. of lime or lemon juice, mixed with 1 oz. of sugar and 1/2 pint of water, shall be served out to each of the crew between the hours of 12 and 1 in the day.

_Adult._ Lemon juice is frequently adulterated, the adulterants being water, sugar, or gum, and sulphuric or acetic acid. The _modus operandi_ is, to dilute the genuine juice with water, and then bring up the density with the sugar or gum, and the percentage of acid with one or other of the above acids. The examination of lemon and lime juice supplied to the navy is now conducted in the Inland Revenue Laboratory, Somerset House, and it speaks well for that department when we say that cases of scurvy on board ships are now of very rare occurrence. No juice is passed unless it comes up to a certain standard in specific gravity, and percentage of citric acid, and any sample containing any other acid is at once rejected.

_Prop._ Lemon juice is refrigerant and antiscorbutic, and has long been extensively employed in the preparation of cooling drinks and effervescing draughts, which are justly esteemed as wholesome summer beverages, as well as palliatives in fevers, nausea, &c. In scurvy, there is no remedy equal to freshly expressed lemon juice; and in acute rheumatism and gout, according to the united testimony of Dr Owen Rees, Dr Babington, and numerous Continental practitioners, it has been exhibited with considerable success. In agues, dysentery, English cholera, nausea, and vomiting, heartburn, putrid sore-throat, hospital gangrene, syphilis, and numerous skin diseases, it has proved most serviceable. See CITRIC ACID, GOUT, &c.

=Lemon Juice, Facti′′tious.= _Syn._ SOLUTIO ACIDI CITRICI, SUCCUS LIMONUM FACTITIUS, L. _Prep._ 1. Citric acid, 1-1/4 oz.; carbonate of potassa, 45 gr.; white sugar, 2-1/2 oz.; cold water, 1 pint; dissolve, add the yellow peel of a lemon, and in 24 hours strain through a hair sieve or a piece of muslin.

2. As the last, but using 15 or 16 drops of oil of lemon, to flavour instead of the lemon peel.

_Obs._ The above is an excellent substitute for lemon juice, and keeps well in a cool place. Tartaric acid, and even vinegar, are sometimes used instead of citric acid; but it is evident that it then loses all claim to being considered as an imitation of lemon juice, and to employ it in lieu of which would be absurd.

=LEM′ON PEEL.= _Syn._ CORTEX LIMONUM (B. P., Ph. L.), L. “The fresh outer part of the rind.” (B. P.) “The fresh and the dried exterior rind of the fruit;” the latter dried “in the month of April or May.” (Ph. L.) Candied lemon peel (CORTEX LIMONUM CONDITUS) is employed as a dessert, and as a flavouring ingredient by cooks and confectioners. It is reputed stomachic. See CANDYING.

=LEMON PIC′KLE.= See SAUCE.

=LEMONADE′.= _Syn._ LEMON SHERBET, KING’S CUP; LIMONADUM, L.; LIMONADE, Fr. _Prep._ 1. Lemons (sliced), 2 in no.; sugar, 2-1/2 oz.; boiling water, 1-1/2 pint; mix, cover up the vessel, and let it stand, with occasional stirring until cold, then pour off the clear through a piece of muslin or a clean hair sieve.

2. Juice of 3 lemons; yellow peel of 1 lemon; sugar, 1/4 lb.; cold water, 1 quart; digest for 5 or 6 hours, or all night, and decant or strain as before.

3. Citric acid, 1 to 1-1/2 dr.; essence of lemon, 10 drops; sugar, 2 oz.; cold water, 1 pint; agitate together until dissolved.

_Obs._ Lemonade is a pleasant, cooling summer beverage, and when made as above may be drank in large quantities with perfect safety. It also forms an excellent refrigerant and antiseptic drink in fevers and putrid diseases generally. Tartaric acid is commonly substituted for citric acid, from being cheaper; it is, however, much, inferior, being less wholesome and less agreeable. Lemonade for icing is prepared as above, only using a little more sugar. Orange sherbet, or orangeade for icing is made in a similar way from oranges.

=Lemonade, Aera′ted.= _Syn._ LIMONADUM AERATUM, L.; LIMONADE GAZEUSE, Fr. _Prep._ 1. (P. Cod.) Water, charged with 5 times its volume of carbonic acid gas, 1 pint; syrup of lemon, 2 oz.; mix.

2. (Without a bottling machine.)——_a._ Into each bottle put lemon syrup, 1 to 1-1/2 oz.; essence of lemon, 3 drops; sesquicarbonate of soda, 1/2 dr.; water, q. s. to nearly fill the bottle; have the cork fitted and ready at hand, then add of tartaric acid (cryst.), 1 dr.; instantly close the bottle, and wire down the cork; it should be kept inverted in a cool place, and, preferably, immersed in a vessel of ice-cold water.

_b._ As the last, but substituting lump sugar, 3/4 oz., for the lemon syrup.

_c._ From lump sugar, 1 oz.; essence of lemon, 3 drops; bicarbonate of potassa, 25 gr.; water q. s., as No. 1; then add citric acid (cryst.), 45 gr., and cork, &c., as before. The last is most wholesome, especially for the scorbutic, dyspeptic, gouty, and rheumatic.

_Obs._ The best aerated lemonade of the London makers is prepared by putting 1-1/2 fl. oz. of rich lemon syrup into each bottle, which is then filled up with aerated water at the bottling machine.

=Lemonade, Antimo′′niated.= _Syn._ LIMONADUM ANTIMONIATUM, L. _Prep._ By adding tartar emetic, 1 gr., to each pint of ordinary lemonade.——_Dose._ A wineglassful every 1/2 hour or hour; as a diaphoretic and expectorant. See ANTIMONY (Potassio-tartrate).

=Lemonade, Ape′′rient.= _Syn._ LIMONADUM LAXATIVUM, L. _Prep._ 1. Sugar, 1 oz.; lemon juice, 3/4 fl. oz.; sulphate of soda, 3 dr.; water, 8 fl. oz.; put them into a soda-water bottle without shaking, have the cork ready fitted, add of sesquicarbonate of soda (in cryst.), 1/2 dr., and instantly cork the bottle, wire it down, and keep it in a cool place, inverted. For a dose.

2. Heavy carbonate of magnesia, 1-1/2 dr.; refined sugar, 1 oz.; essence of lemon, 5 or 6 drops; water, 8 fl. oz.; bottle as last, then add of citric acid (cryst.), 3 dr., and instantly cork, &c., as before. For a dose. It should be kept for at least 24 hours before being taken.

=Lemonade, Lactic.= _Syn._ LIMONADUM LACTICUM, L. _Prep._ (Magendie.) Lactic acid, 1 to 4 dr.; syrup, 2 oz.; water, 1 pint; mix. Recommended in dyspepsia, &c.

=Lemonade, Milk.= _Syn._ LIMONADUM LACTIS, L. _Prep._ Take of sugar, 1/2 lb.; water, 1 pint; dissolve, add the juice of 3 lemons; milk or whey, 1/2 pint; stir the whole together and strain through a hair sieve. Some persons add a glassful of sherry.

=Lemonade, Min′eral.= _Syn._ LIMONADE MINERALE, Fr. On the Continent this name is applied to various drinks consisting of water acidulated with the mineral acids and sweetened with sugar. Thus we have limonade chlorhydrique, nitrique, phosphorique, sulphurique, &c., all of which are used as cooling drinks in fevers, inflammations, skin diseases, &c.

=Lemonade, Port′able.= See POWDERS.

=LEMONADE POWDERS.= See POWDERS.

=LEMONATED KALI.= See KALI, POTASSIUM (Citrate), &c.

=LEN′ITIVES.= In _medicine_, purgatives which act in a gentle manner, and have a soothing effect. See LAXATIVES.

=LENS.= In _optics_, a piece of glass or other transparent medium, having one or two curved surfaces, either convex or concave. A description of the different kinds of lenses belongs to a work on optics. It may, however, be useful to the chemical student to remark here that the CODDINGTON and STANHOPE LENSES, which may now be bought at any of the opticians, neatly mounted and of great power, for a few shillings, will be found of the greatest service in examining minute crystals, precipitates, &c.; and for all ordinary purposes offer a cheap and efficient substitute for more complicated microscopes. An extemporaneous instrument, possessing considerable power, may be made by simply piercing a small circular hole in a slip of metal, and introducing into it a drop of water, which then assumes a spherical form on each side of the metal, while the latter is held in a horizontal position. The ingenious little TOY MICROSCOPES sold about the streets of London, under the form of a perforated pill-box, at one penny each, consist of such a lens made with Canada balsam instead of water, which has the property of hardening without losing its transparency after exposure for a few hours to the air. A still simpler substitute for a lens is a piece of blackened card-paper with the smallest possible needle-hole pierced through it. Any very small object held in a strong light, and viewed through this hole at the distance of about an inch, will appear quite distinct, and from 10 to 12 times larger than its usual size. We have often found this little instrument of incalculable service in situations and under circumstances in which a more powerful or complicated apparatus was unattainable or could not be applied.

Another method for the manufacture of an extemporaneous lens, by Mr Francis, is the following:——Procure a piece of thin platinum wire, and twine it once or twice round a pin’s point, so as to form a minute ring with a handle to it. Break up a piece of flint glass into fragments a little larger than a mustard seed; place one of these pieces on the ring of wire, and hold it in the point of the flame of a candle or of a gas-light. The glass will melt and assume a complete lens-light or globular form. Let it cool gradually and keep it for mounting. It may be mounted by placing it between two pieces of brass which have corresponding circular holes cut in them of such a size as to hold the edge of the lens.

=LEN′TIL.= _Syn._ LENS, L. The seed of the _Ervum Lens_, a plant of the natural order _Leguminosæ_. The lentil is considerably smaller than an ordinary pea, and is of the shape of a double convex lens. Several varieties are cultivated on the Continent of Europe and in many parts of Asia, where they are largely consumed as human food. Lentils are more nourishing than any other description of pulse, but are reputed difficult of digestion, apt to disorder the bowels, and injurious to the eyes. Several alimentary preparations, sold at high prices as cures for dyspepsia, constipation, &c., contain lentil flour as the principal ingredient.

_Composition of Lentils._

Nitrogenous matter 25·2
Starch, &c. 56·0
Cellulose 2·4
Fatty matter 2·6
Mineral matter 2·3
Water 11·5
——————
100·00
(PAYEN.)

Lentils on account of their difficult digestibility require to be very thoroughly cooked. See ERVALENTA and REVALENTA.

=LEPROSY.= _Syn._ LEPRA. A disease of the skin distinguished by circular scaly patches.

=LEPTANDRIN.= A peculiar crystalline principle obtained from the root of _Leptandra Virginica_, a North American plant belonging to the nat. order _Scrophulariaceæ_. Leptandrin is chiefly employed in American medical practice as a cathartic and cholagogue, in which latter function it has been recommended as a substitute for mercury. It is stated to be very serviceable in cases of duodenal indigestion and chronic constipation.——_Dose_, 1/4 to 1/2 grain.

Mr Wayne obtained leptandrin by adding subacetate of lead to an infusion of the root, filtering, precipitating the excess of lead by carbonate of sodium, removing the carbonate of lead by filtration, passing the filtered liquid through animal charcoal to absorb all the active matter, washing the charcoal with water till the washings began to be bitter, then treating it with boiling alcohol, and allowing the alcoholic solution to evaporate spontaneously. By dissolving the powder thus obtained in water, treating this with ether, and allowing the ether to evaporate, needle-shaped crystals were obtained, which had the bitter taste of the root. Leptandrin is soluble in water, alcohol, and ether.

=LETH′ARGY.= _Syn._ LETHARGUS, L. A heavy, unnatural sleep, sometimes bordering upon apoplexy, with scarcely any intervals of waking, from which the patient is with difficulty aroused, and into which he again sinks as soon as the excitement is withdrawn. It frequently arises from plethora, in which case depletion is indicated; or from the suppression of some usual discharge or secretion, which it should then be our business to re-establish. It also often arises from over mental fatigue and nervous debility, when relaxation from business, the use of a liberal diet, and ammoniacal stimulants and antispasmodics, are found useful. When depending on a determination of blood to the head, cupping may be had recourse to, and all sources of excitement avoided. In all cases the bowels should be moved as soon as possible by means of mild purgatives.

=LET′TUCE.= _Syn._ LACTUCA, L. The early leaves or head of the _Lactuca sativa_, or garden lettuce, forms a common and wholesome salad. They are reputed as slightly anodyne, laxative, hypnotic, and antaphrodisaic, and have been recommended to be eaten at supper by those troubled by watchfulness, and in whom there exists no tendency to apoplexy. The leaves and flowering tops of _L. virosa_ are officinal in the B. P., the “flowering herb” (LACTUCA), in the Ph. L.; the “inspissated juice,” in the Ph. E.; and the “inspissated juice and leaves,” in the Ph. D. The “inspissated juice” of _Lactuca virosa_, or strong-scented wild lettuce, is also officinal in the Ph. E.; and both the “leaves and inspissated juice” of the same variety are ordered in the Ph. D. The last species is more powerful than the cultivated lettuce. See EXTRACT and LACTUCARIUM.

=LEUCORRHŒ′A.= _Syn._ WHITES; CATARRHUS VAGINÆ, FLUOR ALBUS, L. The symptoms of this disease are well known to most adult females. The common causes are debility, a poor diet, excessive use of hot tea, profuse menstruation or purgation, late hours, immoderate indulgence of the passions, frequent miscarriages, protracted or difficult labours, or local relaxation. Occasionally it is symptomatic of other affections. The treatment must be directed to the restoration of the general health, and imparting tonicity to the parts affected. Tepid or sea bathing, or shower baths; bark, chalybeates, and other tonics; with local affusions of cold water, and mild astringent injections, as those of black tea or oak bark, are generally found successful in ordinary cases.

=LEVANT′ NUT.= See COCCULUS INDICUS.

=LEVIGA′TION.= _Syn._ LEVIGATIO, L. The process of reducing substances to fine powder, by making them into a paste with water, and grinding the mass upon a hard smooth stone or slab, with a conical piece of stone having a flat, smooth, under surface, called a ‘muller.’ Levigation is resorted to in the preparation of paints on the small scale, and in the elutriation of powders. The term is also, sometimes, incorrectly applied to the lengthened trituration of a substance in a marble or Wedgwood-ware mortar.

=LEVORACE′MIC ACID.= See RACEMIC ACID.

=LEY′DEN JAR.= _Syn._ LEYDEN PHIAL, ELECTRICAL JAR. An instrument for the accumulation of the electric fluid. Its simplest form is that of a wide-mouthed jar of rather thin glass, coated on both sides with tin-foil, except on the upper portion, which is left uncoated, and having a cover of baked wood, through which passes a brass wire, terminating in a metallic knob, and communicating with the inner coating. To charge the jar, the outer coating is connected with the earth, and the knob put in contact with the conductor of an electrical machine. The inner and outer surfaces of the glass thus become respectively positive and negative, and the particles of the glass become strongly polarised. On making connection between the two coatings with a conducting substance, discharge takes place by a bright spark and a loud snap; and if any part of the body be interposed in the circuit, a shock is felt.

=LIBAVIUS’S LIQUOR.= See TIN (TIN CHLORIDE).

=LI′CHEN.= In _pathology_, a dry papulous or pimply eruption of the skin, terminating in scurfy exfoliations. “Lichen exhibits great variety in its outward characters in different individuals; in one the pimples are brightly red; in another, of debilitated constitution, they are bluish and livid; in a third they are developed around the base of hairs; in a fourth they appear as circular groups, and increase by their circumference, while they fade in the centre, forming so many rings of various size; in a fifth, a modification of the preceding, they have the appearance of flexuous bands; while in a sixth they are remarkable for producing intensity of suffering, or unusual disorganisation of the skin. They are all occasioned by constitutional disturbance, sometimes referable to the digestive, and sometimes to the nervous system. In some instances, however, they depend upon a local cause. I have had a crop of lichenous pimples on the backs of my hands from rowing in hot weather; and in hot climates that annoying disorder called prickly heat is a lichen.” (Eras. Wilson.) The treatment of this affection is noticed under ERUPTIONS (Papular).

=LICHENS.= _Syn._ LICHENES——Juss., LICHENALES——Lind., L. In _botany_, these are cryptogamous plants, which appear under the form of thin, flat crusts, covering rocks and the barks of trees. Some of them, like Iceland moss (_Cetraria Islandica_), are esculent and medicinal and employed either as medicine or food; and others, when exposed in a moistened state to the action of ammonia, yield purple or blue colouring principles, which, like indigo, do not pre-exist in the plant. Thus, the _Rocella tinctoria_, the _Variolaria orcina_, the _Lecanora tartarea_, _&c._, when ground to a paste with water, mixed with putrid urine or solution of carbonate of ammonia, and left for some time freely exposed to the air, furnish the archil, litmus, and cudbear of commerce, very similar substances, differing chiefly in the details of their preparation. From these the colouring matter is easily extracted by water or very dilute solution of ammonia. See ARCHIL, CUDBEAR, and LITMUS.

=LIEBER’S HERBS OF HEALTH——Gesundeheitskräuter Liebersche——Blankenheimer Thee——Blankenheimer Tea=——Herba Galeopsidis Grandifloræ Concisa (Yellow Hemp Nettle).

=LIG′ATURE.= In _surgery_, a small waxed piece of cord or string formed of silk or thread, employed for the purpose of tying arteries, veins, and other parts, to prevent hæmorrhage, or to cause their extirpation. To be safe and useful they should be round, smooth, and sufficiently strong to permit of being tied with security without incurring the danger of breaking or slipping. There are many cases recorded in which emigrants, soldiers, and travellers have lost their lives from the simple inability of those around them to apply a ligature.

=LIGHT.= _Syn._ LUMEN, LUX, L. Light acts as a vivifying or vital stimulus on organised beings, just as privation of light, or darkness, disposes to inactivity and sleep. “In maladies characterised by imperfect nutrition and sanguinification, as scrofula, rickets, and anæmia, and in weakly subjects with œdematous (dropsical) limbs, &c., free exposure to solar light is sometimes attended with very happy results. Open and elevated situations probably owe part of their healthy qualities to their position with regard to it.” On the contrary, “in diseases of the eye, attended with local vascular or nervous excitement, in inflammatory conditions of the brain, in fever, and in mental irritation, whether attended or not with vascular excitement, the stimulus of light proves injurious, and, in such cases, darkness of the chamber should be enjoined. After parturition, severe wounds, and surgical operations, and in all inflammatory conditions, exclusion of strong light, contributes to the well-doing of the patient.” (Pereira.)

=LIGHT, ELECTRIC.= We believe we are correct in stating, that within the last two or three years some 600 registrations for patents, more or less, have been taken out for electricity applied to the purposes of artificial illumination. Conceding that many, if not the greater part, of these inventions may prove useless, their number is nevertheless an index of the mental activity that has lately been directed to the subject of electric lighting; and although we are far from affirming that the problem of the practical application of electricity to the lighting of our streets and dwellings may eventually be successfully thought out, still, we think, looking upon these constant endeavours to accomplish the end in view as links in the chain of that experimental evolution and gradation which has characterised the course of most great discoveries, we are justified in regarding them as not altogether improbable auguries and precursors of subsequent success.

Shortly after Faraday’s discovery in 1830 of electrical induction, or the power of a bar of magnetised steel to set up in a certain direction a current of electricity in a coil of insulated wire when introduced into it, Pixü, reducing the result of Faraday’s researches to practice, constructed an instrument, which appears to have been the first dynamic magneto-electric machine. By Pixü’s contrivance a current of electricity was generated by means of the poles of a permanent horseshoe magnet being made to revolve across those of an electro, or temporary magnet, the induced electricity set up in which in its turn established in the surrounding helix a current of electricity, which being made to escape by the terminals or ends of the wire coils could be applied to practical use.

The dynamic electro-magnetic machines of Saxton and Clarke, which succeeded Pixü’s, may be regarded as modifications of this latter, since they differed only in the arrangement of their parts and mode of action. All three machines were chiefly in use in chemical and physical laboratories, whence they have gradually been supplanted by the far more useful Ruhmkorff’s coil, a very powerful variety of the electro-magnetic instrument. In a small form Clarke’s is now chiefly used for medical purposes. That electro-magnetic machines, as cheaper and more convenient sources of electric force, should have been applied to the purposes of telegraphy, will be an obvious inference.

Among the most important and effective of the various instruments for attaining this end, it will suffice to mention the magneto-electric machine of Messrs Siemens and Halske, first brought into use in 1854.

Except, however, in the case of short distances, or with telegraphs belonging to private persons or commercial firms, these instruments have not met with very general adoption. This is owing to the great tension of the induced current, and the consequent difficulty of insulating the wire, particularly for long distances, objections from which the old galvanic apparatus is in a much greater measure free. Mr Henley was the first to use the dynamic magneto-electric machine for working the electric telegraph soon after this instrument had been adopted in England; but as we have seen, the method, except in the cases quoted, have been in great measure abandoned. A large magneto-electric machine has lately been invented by Wheatstone, the induced spark from which is used for firing mines.

The first electro-magnetic machine used for lighting purposes appears to have been one that was the joint invention of MM. Nollet and Van Malderen, of Brussels, a circumstance to which it probably owes its name of the ‘Alliance Machine.’

Nollet, who brought out his invention (which is a modification of Clarke’s) in 1850, originally designed it for the electrolysis of water, the hydrogen resulting from which it was proposed to pass through camphine, or some other hydro-carbon illuminant, and to burn as gas. Additionally it was designed to use the hydrogen as a source of motive power by exploding it in a suitably constructed engine. Owing to the improvements, however, effected in the machine by Van Malderen, by which it became a powerful generator of magneto-electricity, this purpose was abandoned. ‘The Alliance Machine’ consists of a cast-iron frame, on the circumference of which 40 powerful horseshoe magnets, each capable of supporting a weight of 120 to 130 lbs., are fixed, in eight series of 5 magnets each. A number of circular metal discs, around the circumference of which are attached sixteen bobbins of insulated wire fixed to a horizontal shelf turned by a pulley, are in such a position with regard to the magnets, that with each revolution of the shaft each bobbin passes sixteen alternate poles of the magnets, and will have had sixteen alternate currents set up or induced in it. Until replaced by the later and smaller magneto-electric machine, the ‘Alliance’ has been the one mostly employed for the production of the electric light in France, and it is still in use in the lighthouses of Hève and Grisnez, as well as in those of many other places in that country. In 1856 Mr Holmes took out a patent for a machine, which differs from Nollet’s in increasing the number of bobbins by arranging them in concentric circles between two brass discs. By this device the bobbins revolve more quickly in succession in front of the poles of the magnets, a plan which ensures the generation of a greater number of currents for every revolution.

Like the first application of Nollet’s, Holmes’ machine was used for lighthouse illumination. It was in work from December, 1858, until June, 1862, at the South Foreland lighthouse, since which time it has been removed to Dungeness, in the lighthouse of which station it has been in use ever since.

When applied to lighting purposes, both the ‘Alliance’ and Holmes’, and the other machines named, are worked in conjunction with the carbon points, which when arranged with proper machinery constitute the electric lamp.

Wild’s and Ladd’s are powerful dynamic magneto-electric instruments, capable of yielding large quantities of the electric fluid.

Artificial illumination by means of electricity has, however, been more or less occasionally practised for other than lighthouse purposes.

For instance, in 1854, during the building of the Napoleon Docks at Rouen, when 800 workmen were engaged nightly for four hours, the electric light was used for several nights with perfect success, the men being able to carry on their work at a distance of more than 100 yards from the source of the light.

In 1862 and 1863 it was frequently employed in Spain during the night in the construction of railways. During the late Franco-German war in 1870 it was applied to submarine illumination, and more lately it has been used in a series of street illumination in St Petersburg.

The electric light apparatus was placed on the tower of the Admiralty Buildings of that city, and by means of it three of the larger streets were illuminated at night from 7 until 10 o’clock. In this latter case, as well as in that of the Rouen Docks, the lamps were supplied with the electric current generated in batteries.

It may be said, however, to have been only within the last two years that the question of electric lighting has developed into a burning one, and that the light itself has become so much more generally and extensively adopted.

This new era in the history of artificial illumination may be said to date from the introduction of two forms of dynamic magneto-electric apparatus, the one invented by Dr Siemens, the eminent telegraphic engineer, the other by M. Gramme, of Paris, who, from having been formerly a journeyman carpenter, has now become the head of a manufacture which forms a most important branch of scientific industry.

In the apparatus of Gramme and Siemens three marked features and improvements over the older machines have been achieved:——

1. A great reduction in size, and, consequently, in cost, and requisite space for the machine.

2. The method of generating large quantities of electricity by the mutual action between the different parts of the same machine, and the induction therein set up.[14]

[Footnote 14: This discovery was made independently and nearly simultaneously by Drs Siemens and Sir Charles Wheatstone.]

3. The production of the electric current at a much less expenditure of motive power.

On this latter point Professor Tyndall, in his report to the elder brethren of the Trinity House, states that magneto-electric machines of old construction cost ten times more, occupied twenty-five times the space, and weighed fourteen times as much as the recent machines, while they produced only one-fifth of the light with practically the same driving power; which in effect amounts to this——that taking illuminating effect in each case into consideration, the new machines cost one-fiftieth, and are, as regards space occupied, 125 times more advantageous than the earlier forms.

In all the older and larger machines the current of electricity, as it was given off from the wire and passed through the carbon points, was alternate, or first in one direction and then in the opposite——that is, it was a momentary current, first positive and then negative.

In Siemens’ machine, and in one form of Gramme’s, the current is direct——that is, it pursues one uniform course in its passage through the carbon points of the lamp, and in its circuit from the terminal of one wire to that of the other.

Scientific opinion is somewhat at variance as to the disadvantages of the indirect current; many electricians consider that it causes the partial destruction of the contacts, and sets up unnecessary heat in the machine. In magneto-electric machines employed in electro-metallurgic operations, it is essential the current should be a direct one.

In the Gramme machine the electro-magnet consists of a ring composed of soft iron wire attached to a horizontal spindle or axis, which latter is turned by an endless strap revolving on a pulley. Around this iron ring are wound a number of coils, each having 300 turns, of insulated copper wire, each coil being bent inside the ring, and fixed to an insulated piece of brass.

The wire being continuous, each coil is connected with the adjacent one, the whole of the coils thus forming a single conductor. The series of pieces of brass to which the wire is soldered are formed into a circle, which surrounds the axis of the machine, each piece of brass being insulated from its neighbour. The iron-wire ring with its attachments is so arranged, that when the shaft or axis to which it is fixed is turned, it revolves between the poles of a powerful horseshoe magnet in the same plane with it. As it turns the ring gives rise in the coils to two different and diverse currents of electricity, one in one half of the coils around the ring, and the other in the other half.

These currents are made to pass to the circle composed of the insulated pieces of brass, which are arranged radially to the axis of the machine.

Two brass brushes press against these insulated brass radii, one on each side.

These brushes are connected one to each terminal of the machine, and so contrived as always to be in contact with the coils, not becoming insulated from one coil until contact is established with the next one, an arrangement which gives rise to a continuous current of electricity always, and in the same direction.

The Gramme, although of very small dimensions, is an extremely powerful machine. It easily decomposes water, and will heat an iron wire 8 inches in length and a 25th of an inch in diameter to redness.

The following description of the Siemens magneto-electric machine is from a paper read some few months back at the Society of Arts by Dr Paget Higgs, and is extracted from the journal published by that body:

“In the latest form of construction of the Siemens magneto-electric machine the armature, as the revolving coil may be called, consists of several lengths of insulated copper wire, coiled in several convolutions upon a cylinder. The whole surface of the cylinder is covered with wire, laid on in sections, each convolution being parallel to its longitudinal axis. For about two thirds of its surface the wire cylinder is surrounded by curved iron bars, there being just sufficient space left between these curved iron bars and the wire cylinder to allow of its free rotation. The curved iron bars are prolongations of the cores of large, flat electro-magnets; the coils of these electro-magnets and the wire on the cylinder (from brush to brush) form a continuous electrical circuit. On revolving the cylinder (which is supported on a longitudinal axis in suitable bearings, the axis carrying a pulley) an initially weak current is generated into its wires by their passage through the magnetic field, formed by the residual magnetism of the iron coils of the electro-magnets, and the current being directed into the coils of the electro-magnets, increases the magnetism of the cores, which again induce a stronger current in the wire cylinder. This material action may continue until the iron has attained its limit of magnetisation. The maximum magnetic power acting upon each convolution is attained at every revolution of the armature, when the convolution passes through the centre of both magnetic fields, and gradually falls to zero as the convolution becomes perpendicular to that position. Each convolution has, therefore, a neutral position, and a convolution leaving that position on the one side of the axis and advancing towards the north pole of the electro-magnet would be subject to a direct induced current, and that portion of the convolution on the opposite side of the axis would be traversed by a current of opposite direction as regards a given point, but of the same direction as regards circuit. Each of the sections of wire coiled upon the cylinder consists of two separate coils, leaving four ends; two of these ends are connected to each of the segments of a circular commutator divided into parts. But all the coils are connected to the several segments of commutator in such a manner that the whole of the double sections form a continuous circuit, but not one continuous helix. Two brushes placed tangentially to the segments of the commutator collect the electric currents; these brushes are connected one to each electro-magnet, and the two free ends of the electro-magnet coils are connected to the conducting wires leading to the lamp.

“The dimensions, weight, number of revolutions made by the armature, light equivalent in normal candles, and horse-power required for driving, are for the three sizes of machines as follows:——

+----------------------+-------+------------+--------+------------+
| Dimension in Inches. |Weight |Revolutions |Candles’|Horse Power.|
+-------+------+-------+in lbs.|of cylinder.| Light. | |
|Length.|Width.|Height.| | | | |
+-------+------+-------+-------+------------+--------+------------+
| 25 | 21 | 8·8 | 298 | 1100 | 1,000 | 1-1/2 to 2 |
| 29 | 26 | 9·5 | 419 | 650 | 6,000 | 3-1/4 to 4 |
| 44 | 28·3 | 12·6 | 1279 | 480 | 14,000 | 9 to 10 |
+-------+------+-------+-------+------------+--------+------------+

“In the lamp which it is preferred to use with the Siemens machine, the points of the carbons after being separated are brought together again by the gravitation of the top carbon and its holder. The descent of the top carbon actuates by means of the straight rack it carries at its lower end, a large pinion, the spindle of which carries a small pinion, gearing into a second neck attached to the lower carbon holder, the superior weight of the top carbon and holder, in conjunction with the multiplying ratio of the two pinions, producing a continual tendency of the carbons to approach each other. The large and small pinions are connected to each other, and to the spindle that carries them, by an arrangement of friction discs, and the object of this construction is to allow of the two racks being moved equally and simultaneously up or down for the purpose of focussing the light when required. This movement is effected by means of bevelled gearing, and actuated by a milled head, which can be pressed into position when required. On the spindle carrying the large and small pinions and the friction discs is placed a toothed wheel, connected with the spindle by a pawl and ratchet.

“This wheel is the first of a train of wheels and pinions driving a regulating fly in the usual way. The pawl and ratchet are provided to allow of the rapid distancing of the carbon holders when it becomes necessary to introduce fresh carbons. The spindle of the fly also carries a small finely-toothed ratchet wheel. This ratchet wheel is actuated by a spring pawl, carried at the end of a lever, which lever is the continuation of the armature of the electro-magnet, in such a manner that when the armature is attracted by the electro-magnet, the spring pawl engages in the teeth of the ratchet wheel, and causes the wheels in gearing therewith to act upon the racks of the carbon holders to draw them apart.

“The action of the lamp is as follows:——The current passes from the conductor to the top carbon holder, thence through the carbons to the bottom carbon holder, then to the coils of the electro-magnet situated in the base of the lamp. From the coils of the electro-magnet the circuit is completed to the other conductor. Upon the current passing through the circuit, the armature of the electro-magnet is attracted, and the abutment from the armature lever caused to short-circuit the coils of the electro-magnet, releasing the armature. The armature being released, the short-circuit is removed from the coils of the electro-magnet, and the cycle of movement repeated; in this manner an oscillatory motion is given to the armature lever, which by the spring pawl actuates the ratchet wheel, the train of clockwork, and the racks of the carbon holders, forcing the carbons apart until the distance between their points sufficiently weakens the current, so that it no longer attracts the armature of the electro-magnet. Thus, by the combined action of gravitation of the top carbon in drawing the carbons together, and of the current to separate the carbons when they approach too closely, a working distance is maintained between the points with perfect automatism.”

Siemens’ lamp is at the present time employed in the Lizard Lighthouse, in Messrs Siemens’ Engineering Works in England and Wales, as well as in other localities or buildings requiring powerfully lighting up.

An interesting illustration of the value of the electric light to the sailor is furnished by the ‘Telegraph Journal’ of April 5th, 1878. This publication contains a letter from the captain of the S.S. ‘Faraday,’ narrating how that vessel was by its means prevented from running into another vessel during a dense fog.

Siemens’ magneto-electric apparatus and lamp were used on the occasion above referred to.

In every form of contrivance for electrical illumination the lamp or lighting apparatus consists of carbon points separated by a very slight interval, through which the current of electricity passes by means of terminal wires attached to the dynamo-electrical machine.

The lighting effect is produced by the passage of the electric spark through the small gap which separates the carbon points, in which interval extremely minute but solid particles of carbon, given off by the points, are heated up to incandescence in the path of the spark, and thus give rise to the intensely luminous focus known as ‘the electric light.’ The brilliancy of the light of course depends upon the quantity of electricity employed.

A very large number and variety of designs and patents for electric lamps have made their appearance in England, America, France, and Russia within the period following the invention of the small, powerful, and economic dynamo-electric machines of Siemens and Gramme.

The lighting apparatus generally attached to and worked by that variety of Gramme’s machine generating the continuous current is that known as the ‘Serrin Lamp.’ Two carbon electrodes placed vertically one above the other (the positive being the upper one) are fixed on brass holders, which are so connected by a suitably contrived clockwork movement, combined with the working of an electro-magnet in connection with the electric circuit, as to maintain the two carbon poles during their combustion at the necessary distance from each other. Serrin’s lamp differs in detail from Siemens’, but, like this latter, is automatic in principle. In Paris it was the one in general use until the introduction of the Jablochkoff candle, and, with the Duboscq lamp, may be looked upon as the precursor of the various lamps and regulators now employed in electric lighting. Serrin’s lamp or regulator, with some slight modification in the machinery, is also used in the Lontin system of electric illumination, by which separate lights are supplied by separate circuits of electricity. Lontin’s method is that by which the Gaiety Theatre in the Strand is lighted; and is also used at the Western Railway Station (Gare, St Lazare) at Paris. The Jablochkoff candle, which in Paris has lately superseded the Serrin lamp, probably because its use renders unnecessary the use of automatic machinery, is the invention of a Russian engineer, whose name it bears.

It consists of two sticks of gas carbon, about 9 inches long and 1/5th of an inch thick, which are placed vertically side by side, and insulated from one another by a very thin strip of kaolin or china clay (a silicate of alumina and potash), the whole forming a candle. Each carbon rod is connected with one of the terminal wires of a Gramme dynamo-electric machine, the electric current from which, however, not being continuous, sets up an alternate current between the tips or poles of the candles, which are gradually consumed like an ordinary taper, and with this only difference in action between Serrin’s and Siemens’ lamps, that whereas in these latter the spark passes from the top to the bottom carbon point, in the Jablochkoff candle it jumps from side to side. The inventor contends that the kaolin by becoming heated diminishes the resistance of the circuit, and thus permits of the passage of the electric spark more easily through the carbons, and also, we believe, asserts that the kaolin being electrolytically decomposed as the carbons are consumed, becomes converted into silica, which melts and drops down, whilst the aluminium liberated contributes luminosity during combustion to the flame.

One of the chief advantages, however, claimed by M. Jablochkoff is, that he can divide the circuit into a number of different lights, as the resistance of the circuit is uniform.

A large number of Jablochkoff candles are employed in the celebrated ‘Magasins du Louvre,’ one of the most extensive commercial establishments in Paris for the sale of silks, ribbons, gloves, &c., and clothing of every description.

The pure white light diffused by electricity admirably adapts it for viewing colours of all kinds at night, whether seen in pictures or on fabrics and raiments, and more particularly blues and greens, the hues of which are frequently indistinguishable from each other by gaslight. The candle is also used to light the courtyard of the Hotel du Louvre, a large building contiguous to, and with its apartments running over, the Magasins, as well as in several shops.

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 space 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 circumstances, 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 illustration 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.’]