Chapter LXXXV: Part 2 (46)

One of the most useful forms of the voltaic battery is that proposed by the late Prof. Daniell, and commonly known by his name. Its peculiar advantages arise from its action continuing without interruption for a long time; hence the name of ‘constant battery’ that has been applied to it. The foregoing figure will explain the construction of each couple.

One of these couples is sufficient for electro-typing; six of them form a circle of considerable power, and about 20 produce one sufficiently strong for most experiments of demonstration and research.

In arranging these, as well as other batteries, when intensity, or travelling power, is desired, the metallic communication is made between the opposite metals (the zinc of one couple being united with the copper of another); but when simple quantity without intensity is required, the zinc of one battery is united with the zinc of the other, and the copper of the one with the copper of the other——an effect which is equally attainable with a single battery of enlarged dimensions.

Another useful apparatus is GROVE’S BATTERY, in which the positive metal consists of amalgamated zinc immersed in sulphuric acid, diluted with 10 times its bulk of water; and the negative metal of platinum immersed in strong nitric acid. The two liquids are kept separate by the use of porous vessels, as in ‘Daniell’s battery.’ This is an extremely powerful arrangement, but not so constant as Daniell’s, owing to the reduction of the nitric acid to lower oxides of nitrogen. After this battery has been in action for about an hour, copious red nitrous fumes are given off, which cause great annoyance.

In place of platinum, compact charcoal or coke, prepared by a rather troublesome process, may be used, and the arrangement then constitutes a BUNSEN’S BATTERY. Other substitutes for the costly platinum have been proposed, as lead coated with gold or platinum, and iron rendered ‘passive’ by immersion in strong nitric acid. Callan has obtained very good results with amalgamated zinc and cast iron immersed in diluted sulphuric acid, without the use of nitric acid (MAYNOOTH BATTERY).

In SMEE’S BATTERY, which is much used in the arts, pairs of amalgamated zinc and platinised silver (or platinised platinum) are immersed in dilute sulphuric acid (1 part acid to 7 parts water). The plates of zinc are usually bent double, and the platinised plates interposed between the two surfaces formed by the bend. See PLATINISING (p. 1337).

In every voltaic combination the passage of the electricity (_i. e._ the positive modification of the force) in the liquid is from the active element to the inactive element; in the case of a simple zinc-and-copper couple, for instance, it is from the zinc to the copper. If this simple fact be borne in mind, it will decide in every case the question which confuses so many, namely, which is the positive, and which the negative end of a battery? The positive is the end where the electricity leaves the battery; the negative where it re-enters it. For further information connected with the subject of voltaic electricity, see articles on ELECTRICITY, ELECTROLYSIS, ELECTROTYPE, ETCHING, &c.

=VOLUME′TRIC ANALYSIS.= Quantitative chemical analysis by measure. This method of analysis “consists in submitting the substance to be estimated to certain characteristic reactions, employing for such reactions liquids of known strength, and from the quantity of the liquid employed determining the weight of the substance to be estimated by means of the known laws of equivalence.” As an example of this method we give the following from the Introduction in Mr Sutton’s excellent ‘Handbook of Volumetric Analysis,’——“Suppose that it is desirable to know the quantity of pure silver contained in a shilling. The coin is first dissolved in nitric acid, by which means a bluish solution, containing silver, copper, and probably other metals, is obtained. It is a known fact that chlorine combines with silver in the presence of other metals to form chloride of silver, which is insoluble in nitric acid. The proportions in which the combination takes place are 35·46, of chlorine to every 108 of silver; consequently, if a standard solution of pure chloride of sodium is prepared by dissolving 58·46 grains of the salt (_i. e._ 1 equiv. sodium = 23, 1 eq. chlorine = 35·46 = 1 eq. chloride of sodium 58·46) in so much distilled water as will make up exactly 1000 grains by measure; every single grain of this solution will combine with ·108 grain of pure silver to form chloride of silver, which precipitates to the bottom of the vessel in which the mixture is made. In the process of adding the salt solution to the silver, drop by drop, a point is at last reached when the precipitate ceases to form. Here the process must stop. On looking carefully at the graduated vessel from which the standard solution has been used, the operator sees at once the number of grains which have been necessary to produce the complete decomposition. For example, suppose the quantity used was 520 grains; all that is necessary to be done is to multiply ·108 grain by 520, which shows the amount of pure silver present to be 56·16 grains.” The volumetric method is much less troublesome than the ordinary method of analysis (by separating the constituents of a mixture and weighing them), and is admirably adapted for the examination of substances used in arts and manufactures. Most of the processes described under ACIDIMETRY and ALKALIMETRY are examples of this method. See those articles, also EQUIVALENTS, TEST SOLUTIONS, &c.

=WADE’S DROPS.= Compound tincture of benzoin.

=WA′FER PAPER.= See WAFERS, in Cookery (_below_).

=WA′FERS.= Thin adhesive discs, used for securing letters or sticking papers together.

_Prep._ 1. (WAFERS, FLOUR W.) The finest; wheaten flour is mixed with water, either pure or coloured, to a smooth pap or batter, which, after being passed through a sieve, to remove clots or lumps, is poured into the ‘wafer-irons’ (previously warmed and greased with butter or olive oil), and in this state exposed to the heat of a clear charcoal fire; the whole is then allowed to cool, when the irons are opened, and the thin cake, which has become hard and brittle, is cut into wafers by mean of sharp annular steel punches made exclusively for the purpose.

2. (GELATINE WAFERS, TRANSPARENT W.) Good gelatine or glue is dissolved, by the heat of a water bath, in just sufficient water to form a consistent mass on cooling; it is then poured, whilst hot, upon the surface of a warm plate or mirror glass, slightly oiled, and surrounded with a border of card paper (laid flat); a similar plate, also warmed and oiled, is next laid upon the gelatine, and the two plates pressed into as close contact as is permitted by the card paper; when quite cold the thin sheet of gelatine is removed, and cut into wafers with punches, as before. 1 to 2 oz. of sugar is commonly added to each lb. of gelatine.

3. (MEDALLION WAFERS.) A sheet of metal or glass, having designs sunk in it corresponding to the raised part of seals, being provided, the hollows are filled up with a mixture formed of any appropriate coloured powder, made into a paste with gum water or size, leaving the flat part clear; melted coloured glue is then poured on the plate, and the process is otherwise conducted as before. For use, the paper is wetted where the wafer is to be applied.

_Obs._ Care must be taken that no poisonous colours be employed. For gelatine wafers, transparent colours only can be used. Those noticed under LIQUEURS and STAINS (Confectioner’s) are appropriate. To these may be added plumbago, sesquioxide of iron (crocus martis), smalts, levigated vegetable charcoal, and vermilion.

=Wafers.= (In Cookery.) _Prep._ Make fine flour, dried and sifted, into a smooth thin batter with good milk, or a little cream-and-water; add about as much white wine as will make it thick enough for pancakes, sweeten it with a little loaf sugar, and flavour it with powdered cinnamon. When thus prepared have the wafer-irons made ready, by being heated over a charcoal fire; rub them with a piece of linen cloth dipped in butter; then pour a spoonful of the batter upon them, and close them almost immediately; turn them upon the fire, and pare the edges with a knife, if any of the batter oozes out. A short time will bake them, when the irons are perfectly heated. The wafers must be curled round whilst warm when they are for ornaments. ‘Wafer paper’ is prepared in a similar way to the above; but when intended to be kept for some time, the milk must be omitted. Used by cooks, &c.; and, recently, as an envelope for nauseous medicines.

=Wafers, Da Silva’s.= These nostrums were introduced to the public some time ago, as though they were prepared from the formulæ of a celebrated physician whose name was affixed to them.[256] There are three varieties, which are said to be prepared as follows:

[Footnote 256: For an exposition of the Da Silva quackery, with Or Locock’s letter on the subject, see the ‘Anat. of Quackery,’ or the ‘Med. Cir.,’ ii, 106-126.]

1. APERIENT OR ANTIBILIOUS WAFERS. From sugar and extract of liquorice (Spanish juice), equal parts; senna and jalap, of each in fine powder, about 1/2 dr. to every oz. of sugar employed; made into a mass with a concentrated infusion of senna, and divided into 12-gr. lozenges or squares with the corners rounded off.

2. FEMALE WAFERS. From sugar, horehound candy (or honey), and aperient wafer mass, equal parts; beaten to a proper consistence with weak gum water, to which a little orange-flower water has been added, and divided into 8 gr. tabellæ, as before.

3. PULMONIC WAFERS. From lump sugar and starch, of each in powder, 2 parts; powdered gum, 1 part; made into a lozenge-mass with vinegar of squills, oxymel of squills, and ipecacuanha wine, equal parts, gently evaporated to 1-6th their weight, with the addition of lactucarium in the proportion of 20 to 30 gr. to every oz. of the dry powders, the mass being divided into half-inch squares, weighing about 7-1/2 gr. each (when dry), as before.

=WAL′NUT.= The _Juglans regia_, a tree of the natural order _Juglandaceæ_. The sap yields sugar; the fruit is the walnut; the kernels of the latter are eaten and pressed for their oil; the peel or husks are used for ‘rooting’ or dyeing brown; the unripe fruit is pickled, and its juice is used as a hair dye; the leaves are reputed diaphoretic and antisyphilitic; and the wood is esteemed for cabinet work.

=WARBURG’S FEVER DROPS.= See TINCTURE, WARBURG’S FEVER.

=WARD’S RED DROP.= A strong solution of emetic tartar in wine.

=WARTS.= _Syn._ VERRUCÆ, L. These chiefly attack the hands, and may be removed by the daily use of a little nitrate of silver, nitric acid, or aromatic vinegar, as directed under CORNS. The first of the above applications produces a black stain, and the second a yellow one; both of which, however, wear off after the lapse of some days. Acetic acid scarcely discolours the skin. Erasmus Wilson, the eminent surgeon and talented author of several works on the skin, mentions the case of a gentleman who removed an entire crop of warts from his knuckles and fingers by subjecting them to a succession of sparks from one of the poles of an electrical machine. “He was in the habit, as is usual, of trying the amount of electric fluid collected in his machine by placing his knuckle near the brass knob, and receiving a spark. Observing that an odd sensation was produced whenever the spark struck a wart, he was tempted for amusement to give them a round of discharges. When his attention was next directed to his hands he found, to his surprise and satisfaction, that all the warts had disappeared.” Dr Peez, of Wiesbaden, recommends the internal use of carbonate of magnesia in cases of warts.

The papular eruption which covers the hands of some persons, and which is occasionally called ‘soft warts,’ is best removed by the daily use of Gowlard’s lotion.

=WASH.= The fermented wort of the distiller.

=WASH-BALLS.= See SAVONETTES.

=WASH-BOTTLE.= The principle of this very common and indispensable laboratory utensil, by which precipitates are washed, will be readily understood by reference to No. 1 of the engravings below.

The bottle being two thirds filled with distilled waters by blowing into the shorter tube, _b_, a small jet of water is forced through the nozzle of the longer tube, _c_. We give the following directions for the construction of a WASH-BOTTLE, from Mr Clowes’ excellent little manual, entitled ‘An Elementary Treatise on Practical Chemistry,’[257]——“A thin, flat-bottomed flask is chosen, of 16 or 18 ounces capacity; the neck must not be less than an inch in diameter. Procure a sound cork, which is slightly too large to enter the neck, soften the cork by placing it upon the floor and rolling it backwards and forwards under the foot with gentle pressure; when thus softened the cork must fit tightly into the flask.[258] Two pieces of glass tubing rather longer than would be required for the tubes _a_ and _b_ are then bent into the form shown in Fig. 1. The ends of the tubes are, if necessary, cut off to the right length, and their sharp edges rounded by holding them in the Bunsen flame, or the tip of the blowpipe flame.

[Footnote 257: J. and A. Churchill, New Burlington Street.]

[Footnote 258: “A vulcanized india-rubber stopper is much more durable for this and most other chemical processes. It is perforated by a sharp, well-wetted cork bore, or by a wetted round file.”]

“Two parallel holes are then bored in the cork by means of a round file, or by a proper size cork-borer: the holes must be rather smaller than the glass tubes, and must not run into one another, or to the outside of the cork. They are slightly enlarged, if necessary, by the round file. Into these holes the tubes _a_ and _b_ are then pushed with a twisting motion; if the holes have been made of the proper size the tubes must enter somewhat stiffly, but without requiring much pressure. Upon the upper end of a is fitted a small piece of india-rubber tubing, about an inch and a half in length, and into the other end of this is a finished short jet (_c_) made by drawing out a piece of glass tubing in the flame; its nozzle may be constructed, if necessary, by holding it perfectly dry in the flame for some time. The neck of the bottle should then be bound round with twine, like the handle of a cricket-bat, or tightly covered with a piece of flannel. This prevents the fingers from being burnt when the bottle contains boiling water.”

We append below some varieties of washing bottles. The round-bottomed are in more general requisition than the flat-bottomed description; although this latter presents the advantage of standing more firmly, and, if boiling water be required, of furnishing it more quickly than the bottle with the round base.

In some laboratories earthenware bottles are in use. These are not so easily broken as those made of glass, but, unlike these latter, water cannot be boiled in them, neither can we see whether they be full or empty.

=WASHERWOMAN’S SCALL.= See PSORIASIS.

=WASHES.= The familiar name of lotions, more especially of those employed as cosmetics. See FRECKLES, LOTION, MILK OF ROSES, SKIN COSMETICS, &c., and the following page.

=Washes, Hair.= _Prep._ 1. From rosemary tops, 2 oz.; boiling water, 1 pint; infused together in a teapot or jug, either with or without the addition of rectified spirit, 1 fl. oz. (or rum, 2 fl. oz.) to the cold strained liquor.

2. Box leaves, a small handful; boiling water, 1 pint; digest for an hour, simmer 10 minutes, and strain. Both are used to improve the growth of and to strengthen the hair.

3. To clean the ‘partings,’ remove scurf, &c.——_a._ (ANTIPITYRIENNE.) From sesquicarbonate of ammonia, 1 oz.; spirit of rosemary, 1/2 pint; rose of elder-flower water, 1-1/2 pint.

_b._ (DETERGENT ESSENCE.) From honey, 2 oz.; borax, 1 oz.; cochineal (bruised), 1/4 oz.; camphor, 1 dr.; (dissolved in) rectified spirit, 2 fl. oz.; soft water, 3/4 pint; oil of rosemary, 20 drops.

_c._ (VEGETABLE EXTRACT.) Take of salt of tartar, 1 oz.; rosemary water, 1 pint; burnt sugar, q. s. to tinge it brown; dissolve, filter, and add of essence of musk, 10 drops.

4. To darken the hair.——_a._ From pyrogallic acid, 1/4 oz.; distilled water, orange-flower water, and rectified spirit, of each 1-1/4 fl. oz.

_b._ (LA FOREST’S COSMETIC LOTION or LIQUID HAIR DYE.) Boil, for a few minutes, chloride of sodium, 1 dr., and sulphate of iron, 2 dr., in red wine, 1 lb.; then add of verdigris, 1 dr.; in 2 or 3 minutes remove it from the fire, and further add of powdered galls, 2 dr.; the next day filter. For use, moisten the hair with the liquid; in a few minutes dry it with a cloth, and afterwards wash the skin with water.

5. To prevent the hair falling off.——_a._ (AMERICAN SHAMPOO LIQUID.) Take of carbonate of ammonia, 1/2 oz.; carbonate of potash, 1 oz.; water, 1 pint; dissolve, and add the solution to a mixture of tincture of cantharides, 5 fl. oz.; rectified spirit, 1 pint; good rum, 3 quarts. Used to strengthen the hair and to remove dandruff, by moistening it with the mixture, rubbing so as to form a lather, and then washing with cold water.

_b._ (BALM OF COLUMBIA.) As the last, omitting the potash, quadrupling the carbonate of ammonia, and adding some perfume.

_c._ (Eras. Wilson.) Eau de Cologne (strongest), 8 fl. oz.; tincture of cantharides, 1 fl. oz.; oils of rosemary and lavender, of each 1/2 fl. dr.

_d._ (Dr LOCOCK’S LOTION.) From expressed oil of mace (nutmeg), 1 oz., liquefied, at a gentle heat, with olive oil, 1/2 oz.; and, when cold, formed into an emulsion by agitation, with rose water, 1/4 pint; spirit of rosemary, 2-1/2 fl. oz.; stronger liquor of ammonia, 1-1/2 fl. dr. For other formulæ, see BALDNESS, HAIR DYES, LOTION, &c.

=Washes, Medicinal.= See LOTION, &c.

=Washes, Mouth.= _Syn._ TOOTH WASHES; COLLUTORIA, L. _Prep._ 1. Take of camphor (cut small), 1/4 oz.; rectified spirit, 2 fl. oz; dissolve. A few drops to be added to a wine-glassful of water, to sweeten the breath and preserve the teeth.

2. Chloride of lime, 1/2 oz.; water, 2 fl. oz.; agitate well together in a phial for 1/2 an hour, filter, and add, of rectified spirit, 2 fl. oz.; rose or orange-flower water, 1 fl. oz. Used, highly diluted with water, as the last, by smokers and persons having a foul breath.

3. Mastic (in powder), 2 dr.; balsam of Peru, 1/2 dr.; gum, 2 dr., or q. s.; orange-flower water, 6 fl. oz.; tincture of myrrh, 2 fl. dr.; for an emulsion. In loose teeth, &c.

4. Tannin, 1/2 dr.; tincture of tolu, 2 fl. dr.; tincture of myrrh, 6 fl. dr.; spirit of horseradish, 2 fl. oz.; mix. In spongy gums, scurvy, &c.; diluted with tepid water.

5. (Swediaur.) Borax, 1/4 oz.; water and tincture of myrrh, of each 1 fl. oz.; honey of roses, 2 oz. In tender or ulcerated gums.

6. Balsam of Peru, 2 dr.; camphor, 1/2 dr.; essence of musk and liquor of ammonia, of each 1/2 fl. dr.; tincture of myrrh, 3 fl. dr.; spirit of horseradish, 1-1/2 fl. oz. To sweeten and perfume the breath; a teaspoonful in 1/2 wineglassful of tepid water to rinse the mouth with.

=Washes for the Nose.= _Syn._ NASAL DOUCHES, COLLUNARIA. The following formulæ medicinally employed for the purpose of washing or rinsing out the nostrils are from the ‘Pharmacopœia of the Throat Hospital.’

In applying them it is directed that “not more than twenty ounces of fluid should ever be used for a nasal douche, and ten ounces are generally sufficient. If an apparatus on the syphon principle be applied, it should be placed only just above the level of the patient’s head, in order to avoid too great force of current. The temperature of the fluid should be about 90° F.”

NASAL DOUCHE OF TANNIC ACID. _Syn._ COLLUNARIUM ACIDI TANNICI. _Prep._ Tannic acid, 3 grams; water, 1 oz.; dissolve.——_Use._ Astringent

NASAL DOUCHE OF ALUM. _Syn._ COLLUNARIUM ALUMINIS. _Prep._ Alum, 4 grams; water, 1 oz.; dissolve.——_Use._ As a mild astringent.

NASAL DOUCHE OF PERMANGANATE OF POTASH. _Syn._ COLLUNARIUM POTASSÆ PERMANGANATIS. _Prep._ Solution of permanganate of potash (B. P.), 6 minims. Water to 1 oz.; mix.——_Use._ Detergent.

NASAL DOUCHE OF QUININE. _Syn._ COLLUNARIUM QUINIÆ. _Prep._ Sulphate of quinine, 1/2 grain; water, 1 oz. Dissolve by the aid of a gentle heat.

This solution is occasionally useful in hay-fever. It is generally sufficient to place a little in the palm of the hand and draw it up through the nose.

NASAL DOUCHE OF SULPHO-CARBOLATE OF ZINC. _Syn._ COLLUNARIUM ZINCI SULPHO-CARBOLATIS. _Prep._ Sulpho-carbolate of zinc, 2 grams; water, 1 oz.; dissolve.——_Use._ Antiseptic.

=Washes, Tooth.= See _above_.

=WASHING (as applied in Chemistry).= In the chemical laboratory the washing of precipitates is an operation of constant occurrence, and as the accurate result of the quantitative analysis in which the process of precipitation is had recourse to, essentially depends upon the manner in which the washing has been carried out, we have thought it desirable in the interest of the worker commencing practical chemistry to amplify under the present section the remarks which occur under the article ‘Precipitation.’ In washing a precipitate the object is, of course, to entirely free it from all extraneous matter, so as to ensure, after proper drifting, its being weighed in an absolutely pure and uncontaminated state. To arrive at a correct knowledge as to when a precipitate has been properly washed, the operator must never trust to guesswork, but to _ocular demonstration_, by testing a minute portion, such as a drop or so of the washings, from time to time.

This may be done, either by adding——1. A very minute quantity of the proper precipitant[259] to the washings; or——2. By evaporating a drop of the latter on a platinum knife, or a piece of platinum foil; when, if in the former case no turbidity is caused and in the latter no fixed residue remain, the precipitate may be pronounced perfectly washed. The operator, however, instead of not sufficiently washing his precipitate, is frequently liable to fall into another dilemma, which consists not so much in overwashing it as in washing it with an unsuitable liquid, or one in which the precipitate is, to a greater or lesser extent, soluble.

[Footnote 259: See PRECIPITATE]

It may not unfrequently happen that the best available precipitant may be one in which the precipitate is soluble to some small extent. Under these circumstances, before throwing down the precipitate, the liquid should, as far as practicable, be removed by evaporation.

Many precipitates which are not altogether insoluble in water may, by the addition of some other liquid to the water, be rendered much less so. Thus, the double chloride of platinum and ammonium which is incompletely thrown down in water is perfectly precipitated if alcohol be added to the water, as are also chloride of lead and sulphate of lime, whilst the basic phosphate of magnesium and ammonium may be rendered insoluble in water by the addition of ammonia to the water. The precipitate having subsided to the bottom of the fluid in which it was suspended, the supernatant liquid may be removed from it either by filtration or decantation. In some cases both processes are had recourse to. To wash a precipitate which has been separated by filtration, and which in a moist condition more or less fills the paper-filter inserted in a proper funnel, the wash-bottle described below is employed. In using this apparatus the jet of water that is made to issue from the bottle should be denoted upon the sides of the filter, and never in the centre, since this would cause a splashing and a consequent loss of the precipitate. The same contingency would be liable to follow it the waters were propelled too violently from the bottle. On no account must the wash-water be allowed to reach to the top of the filter. Another precaution to be guarded against is the formation in the precipitate of fissures or channels; if these are not prevented, the water will not permeate all the parts of the precipitate, and it will be only very insufficiently washed. When such channels form, it will be best to stir up the precipitates with a glass rod or a platinum spatula, taking care, however, to avoid tearing or making a hole in the filter.

Precipitates that are washed by decantation ought to consist of such substances as readily subside from the liquid in which they are suspended and are practically insoluble in water, since a very much larger quantity of this menstruum has to be employed than when filtration is had recourse to. The process is generally carried out in deep vessels. The supernatant liquid being removed, the vessel is filled up with water, and the precipitate well stirred up with a glass rod; after it has again fallen down fresh water is added, and the process is continued until the washings cease to show the presence of any soluble matter. The several washings being collected, are let stand some 12 or 24 hours; after which time, should no precipitate show itself, they are thrown away. Should any deposits form in the washing, it is carefully removed either by filtration or decantation, and its amount being determined, the result is added to that obtained from the bulk of the precipitate. Where the nature of the precipitate is in no way influenced by hot water, this latter should always be used in washing precipitates, as it greatly facilitates and expedites the operation. Many precipitates require to stand a long time before they entirely subside from the fluid in which they are suspended. Most gelatinous, pulverulent, and crystalline precipitates are of this nature. The separation of the precipitate should not be attempted until after the liquid containing the precipitate has stood several hours.

=WASHING FLU′IDS.= Solutions of carbonate of soda, rendered caustic with quicklime.

=WASHING POW′DERS.= See POWDERS.

=WATCH′FULNESS.= _Syn._ SLEEPLESSNESS. AGRYPNIA, L. The common causes of watchfulness are thoughtfulness or grief, disordered stomach or bowels, heavy and late suppers, and a deficiency of outdoor exercise. The best treatment, in ordinary cases, simply consists in an attention to these points. The method of producing sleep recommended by a late celebrated hypnotist consists in merely adopting an easy recumbent position, inclining the head toward the chest, shutting the eyes, and taking several deep inspirations with the mouth closed. Another method, recommended by an eminent surgeon, and which appears infallible if persevered in with proper confidence, and which is suitable either to the sitting or recumbent posture, consists in tying a decanter cork with a bright metallic top, a pencil-case, or any other bright object on the forehead, in such a position that the eyes must be distorted or strained to be capable of seeing it. By resolutely gazing in this way for a short time, without winking, with the mind fully absorbed in the effort, the muscles of the eyes gradually relax, and the experimenter falls asleep. Gazing in a similar manner on any imaginary bright spot in the dark, as at night, exerts a like effect. A tumblerful of cold spring water, either with or without a few grains of bicarbonate of potash in it, taken just before lying down, will frequently succeed with the dyspeptic and nervous, when all other means fail.

The following valuable advice to those who suffer from unnatural wakefulness is abridged from the late Dr Tanner’s valuable work on the ‘Practice of Medicine.’[260]

[Footnote 260: ‘The Practice of Medicine,’ by Thos. Hawkes Tanner, M.D., Renshaw, London.]

As his starting point Dr Tanner enjoins the practice of taking a proper amount of exercise daily. A digestible diet, such as is not liable to cause acidity or flatulence, must also be adopted, and tea and coffee must be abstained from in the after part of the day. Early dinners and light suppers are also recommended. The reading of any thrilling work of fiction previous to retiring to rest is also prohibited. The patient is advised to seek his bed at an early and regular hour, and it is desirable to have his sleeping chamber well ventilated, and if the weather be chilly the bedroom fire should be lighted. Feather beds should be abandoned for mattresses; there should not be too many blankets on the bed, the pillows should be firm and high, and no curtains or hangings should be allowed. Should the above means fail to produce the required sleep, before going to bed the patient is advised to try a tumbler of port-wine negus, or of mulled claret, or of white-wine whey, the last thing. The aged are recommended (should the above methods be unsuccessful) to imbibe a glass of spirit and water, which is said to be all the more effective if drunk when in bed. In some cases, attended by a hot or dry skin, a glass of cold water has been found useful. Another remedy is the use of a bath, for about three or five minutes, just before getting into bed, at a temperature varying from 90° to 96° F.

Rapid sponging of the body with tepid water is also recommended, as also the use of a warm foot bath, at a temperature of 100° F., or of a hot-water bottle in the bed, or putting the feet in cold water for a minute, and then vigorously rubbing them.

For those whose sleeplessness is caused by their prosecuting literary work till a late hour a short brisk walk, just before retiring to bed, is recommended.

If the wakefulness can be traced to any bodily ailment, this, of course, must be removed by the proper means. Constipation, which is not at all an unfrequent cause of insomnia, must be combated by the methods described under that article. If there be headache it will be best removed by applying a rag dipped in cold water to the scalp, or a bladder containing ice.

Should the adoption of any of the above suggestions fail all kinds of mental labour and excitement during the day must be greatly diminished, and physical exercise must replace them. Sedatives should be had recourse to with great caution, and under medical supervision only. Because of the hazard attending their use, and of the ready tendency their adoption has to degenerate into a pernicious ineradicable habit, we have forebore to specify the medicinal agents Dr Tanner prescribes for sleeplessness, strongly recommending the patient, before he has recourse to them, to exhaust the category of suggestions given by Dr Tanner, and, should these unhappily be found to fail, and he is drawn to soporifics, we again reiterate, let him take them only under medical supervision.

Another method, adopted by professional hypnotists, consists in gently moving, in opposite directions, a finger of each hand over the forehead, just above the eyebrows. A soothing and drowsy effect is said to be thereby produced, which ends in tranquil slumber.

Dr Ainslie Hollis contributes some excellent hints on the treatment of wakefulness to the practitioner. He classifies the treatment under two heads——first, the induction of natural sleep, and, secondly, the production of narcosis or artificial rest. The application of mustard plasters to the abdomen generally brings about the first result, producing, according to Schuler, first dilatation, and subsequently contraction of the vessels of the pia mater. Dr Pleyer, of Jena, on the supposition that sleep may be induced by the introduction of the fatigue products of the body, advocates the administration of a solution of lactate of soda. When sleeplessness is the result of brain exhaustion Dr Hollis advocates a tumbler of hot claret negus. The alkalies and alkaline earths, says the ‘Boston Journal of Chemistry,’ are useful when acid dyspepsia is associated with the insomnia. In hot weather, sprinkling the floor of the sleeping apartment with water lessens the irritant properties of the air, adding much to the comfort of the sleepers; possibly the quantity of ozone is at the same time increased. When sleep is broken by severe pain, opium or morphia is of value, bringing not only relief, but producing anæmia of the cerebral vessels; when neuralgia is the cause an injection of morphia under the skin, near the branch of the affected nerve, will have more effect than by administering it by the mouth. Again, when wakefulness is due to defective cardiac power, digitalis may be useful. Chloral hydrate is supposed to owe its hypnotic effect to its power of diminishing the amount of blood in the brain, and therefore it may be used when sleeplessness arises from the pains of muscular spasm. The bromides, although undoubtedly sedatives, possess very doubtful hypnotic properties. See SUPPER, &c.

=WA′TER.= H_{2}O. _Syn._ OXIDE OF HYDROGEN, PROTOXIDE OF H.; AQUA, L.; EAU, Fr.; WASSER, Ger.; ὑδωρ, Gr. The ancients regarded water as a simple substance, and as convertible into various mineral and organic products. Earth, air, fire, and water were at one time conceived to be the elementary principles or essences of matter from which all form and substance derived their existence. The true constitution of water was not discovered until about the year 1781, when Cavendish and James Watt, independently and nearly simultaneously, showed it to be a compound of hydrogen and oxygen. Five years, however, before this time (1776), the celebrated Macquer, assisted by Sigaud de la Fond, obtained pure water by the combustion of hydrogen in the air. It has since been satisfactorily demonstrated that hydrogen and oxygen exist in water in the proportion of 1 to 8 by weight, or 2 to 1 by volume; the sp. gr. of hydrogen being to that of oxygen as 1 to 16. One cubic inch of perfectly pure water at 62° Fahr., and 30 inches of the barometer, weighs 252·458 gr.; by which it will be seen that it is 770 times heavier than atmospheric air. Its sp. gr. is 1·0, it being made the standard by which the densities of all solid and liquid bodies are estimated. The sp. gr. of frozen water (ice) is ·9175, water being 1·0 (Dufour); that of aqueous vapour (steam), ·6252, air being 1·0. Water changes its volume with the temperature; its greatest density is about 39-1/2° Fahr., and its sp. gr. decreases from that point, either way. Water is nearly incompressible. By subjecting water to a pressure of 705 atmospheres, Cailletet found the compressibility to be at the rate of ·0004451 for each atmosphere. Water evaporates at all temperatures; but at 212° under ordinary circumstances, this takes place so rapidly that it boils, and is converted into vapour (steam), whose bulk is nearly 1700 times greater than that of water.

_Var._ Of these the following are the principal:

DISTILLED WATER; AQUA DESTILLATA (B. P., Ph. L., E., & D.), L. Obtained by the distillation of common water through a block-tin worm, rejecting the first and last portions that come over. The still employed for this operation should be used for no other purpose; and when great nicety is required, the distillation should be performed in glass or earthenware. It remains limpid on the addition of lime water, chloride of barium, nitrate of silver, oxalate of ammonium, or hydrosulphuric acid. It is the only kind of water that should be employed in chemical and pharmaceutical operations. When distilled water is not at hand, clean filtered or clarified rain water is the only kind that can be successfully substituted.

NATURAL WATERS. In respect of wholesomeness, palatability, and general fitness for drinking and cooking, natural waters may be classified in orders of excellence as follows (‘Rivers Pollution Commissioners’ Sixth Report’):——

{1. Spring water } Very palatable.
_Wholesome_ {2. Deep-well water }
{3. Upland surface water } Moderately palatable.
{4. Stored rain water }
_Suspicious_ {5. Surface water from cultivated lands }
{6. River water to which sewage gains } Palatable.
_Dangerous_ { access }
{7. Shallow well water }

The average composition of the four classes of unpolluted waters is given by the same authorities as follows. Their estimations are in parts per 100,000, but may be converted in grains per gallon by multiplying by 7 and dividing by 10:

--------------+------+-------+--------+-----+--------+--------
| | | | |Nitrogen|Total
|Total |Organic|Organic |Ammo-| as |combined
|solid |Carbon |Nitrogen| nia |nitrates|nitrogen
|im- | | | | and |
|purity| | | |nitrites|
--------------+------+-------+--------+-----+--------+--------
Rain water | 2·95| ·070 | ·015 | ·029| ·003 | ·042
Upland surface| | | | | |
water | 9·67| ·322 | ·032 | ·002| ·009 | ·042
Deep-well | | | | | |
water | 43·78| ·061 | ·018 | ·012| ·495 | ·522
Spring water | 28·20| ·056 | ·013 | ·001| ·383 | ·396
--------------+------+-------+--------+-----+--------+--------

--------------+---------+--------+-----------------
|Previous | | Hardness
|sewage | +-----+-----+-----
|or animal|Chlorine|Temp-|Perm-|Total
|contamin-| |orary|anent|
| ation | | | |
--------------+---------+--------+-----+-----+-----
Rain water | 42 | ·22 | ·4| ·5 | ·3
Upland surface| | | | |
water | 10 | 1·13 | 1·5| 4·3 | 5·4
Deep-well | | | | |
water | 474 | 5·11 | 15·8| 9·2 |25·
Spring water | 3559 | 2·49 | 11·0| 7·5 |18·5
--------------+---------+--------+-----+-----+-----

RAIN WATER contains, among natural waters, the smallest amount of solid matter in solution. From the columns headed “Organic Carbon” and “Organic Nitrogen” it will be seen that even rain collected with special precautions, away from any large town, is by no means free from organic matter. Rain water collected from roofs and stored in underground tanks is often very impure.

SURFACE WATERS form the main supply of rivers. If collected from high uncultivated districts they are usually unpolluted with animal matter. The organic matter is usually peaty, is sometimes very small, but is liable to considerable variations with the season, and is occasionally present in excessive quantities, discolouring the water and rendering it unpalatable. From their softness these waters are admirably adapted for manufacturing purposes. The amount of solid matter in solution ranges from 2 to 7 grains per gallon.

SURFACE WATER from _cultivated land_, contains on an average less organic matter than upland surface water, but the pollution, being derived from manure and other objectionable matter, is more harmful.

RIVER WATER consists of the above, aided by springs, and most frequently the drainage of towns on its banks. The amount of solid matter varies from 10 to 30 grains per gallon. In Thames water there are on the average about 20 grains.

WELLS, if _shallow_, are usually a most undesirable supply. Unless far from any house they are contaminated by drainage, and sometimes, from proximity to cesspools, contain more animal matter than ordinary town sewage. They are, as a class, hard waters, the polluted ones excessively so.

Wells of 100 feet deep and upwards are, as a class, very superior waters, the filtration and oxidation of so great a depth of soil having removed the greater part of the organic matter. The hardness varies with the strata, but, as a class, the deep wells are softer than the shallow.

SPRING WATER greatly resembles deep well water, possessing all its good qualities in a higher degree. Spring and deep well water are very uniform in quality, and little affected by climatic changes.

SEA WATER. The characteristic of this variety is its saltness. Its density is about 1·0274, and the average quantity of saline matter which it contains is about 3-1/2 per cent., of which about 27/35 are chloride of sodium, and the remainder chiefly chloride of magnesium and sulphate of magnesium.

The average proportion of organic carbon and nitrogen in 23 samples of sea water was ·278 carbon, ·165 nitrogen, as compared with Thames water averages of ·203 parts carbon, ·033 nitrogen, in 100,000 parts of water.

_Analysis of sea water_ (British Channel), by Dr Schweitzer, of Brighton:——

1000 gr. contained—— Grains
Water 963·745
Chloride of sodium 28·059
Chloride of potassium 0·766
Chloride of magnesium 3·666
Bromide of magnesium 0·029
Sulphate of magnesium 2·296
Sulphate of calcium 1·406
Carbonate of calcium 0·033
————————
1000·

_Pur._ Pure water is perfectly transparent, odourless, and colourless, and evaporates without residue, or even leaving a stain behind. The purest natural water is that obtained by melting snow or frozen rain, that has fallen at some distance from any town. Absolutely pure water can only be obtained by the union of its gaseous constituents; but water sufficiently pure for all purposes may be procured by the careful distillation of common water.

Among the methods adopted for improving the quality of water are:

(_a_) _For reducing the amount of organic and suspended matter._——1. Filtration through or agitation with coarsely powdered, freshly burnt charcoal, either animal or vegetable, but preferably the former. When in good condition a filter of animal charcoal will not only remove suspended matter in water, but will considerably reduce the amount of organic matter, and also the calcareous and gaseous impurities held in solution; but it, however, loses its power of removing lime in a week or two, and of abstracting the organic matter in about three to four months, and then becomes foul, and requires to be recharged. Spongy metallic iron is more energetic in its action than charcoal, and remains serviceable for a twelvemonth. 2. Free exposure to the action of the air, by which the organic matters become oxidised and insoluble, and speedily subside. This may be easily effected by agitating the water in contact with fresh air, or by forcing air through it by means of bellows. 3. The addition of a little sulphuric acid has a like effect; 15 or 20 drops are usually sufficient for a gallon. This addition may be advantageously made to water intended for filtration through charcoal, by which plan at least 2/3 of the latter may be saved. (Lowitz.) 4. An ounce of powdered alum (dissolved), well agitated with a hogshead or more of foul water, will purify it in the course of a few hours, when the clear portion may be decanted. When the water is very putrid about 1/2 dr. (or even 1 dr. per gall.) may be employed; any alum that may be left in solution may be precipitated by the cautious addition of an equivalent proportion of carbonate of sodium. 5. A solution of ferric sulphate acts in the same way as alum; a few drops are sufficient for a gallon. 6. Agitation with about 1/2 to 1 per cent. of finely powdered black oxide of manganese has similar effect to the last. 7. The addition of a little aqueous chlorine, or chlorine gas, to foul water, cleanses it immediately. This method has the advantage of the water being perfectly freed from any excess of the precipitant by heat.

(_b_) _For reducing amount of inorganic matter._——1. Distillation separates all non-volatile matter, including organised bodies. It is used to obtain a potable water from sea water. The waste heat of the cook’s galley is amply sufficient for this purpose. There are several patent contrivances for the distillation of water on ship board. 2. Hard water may be softened by adding carbonate of soda to the water so long as it turns milky. The precipitation of the hardening ingredients, lime and magnesia, is most rapid when the water is heated. The water cannot be used for drinking purposes, from the unpleasant flavour of the carbonate of soda. When used on a hard water intended for washing, it effects a saving of soap equal to about fifteen times its own cost. Sea water can be made fit for washing by this means. It removes both the “temporary” hardness, due to carbonates of calcium and magnesium, and the “permanent,” due to the sulphates, chlorides, and nitrates of these metals. 3. Hard water may be both aerated and softened by the addition of a few grains of bicarbonate of potassium per gallon, followed by half as much lime juice or tartaric acid as is sufficient to saturate the alkali in the carbonate thus added. 4. The “temporary” hardness may be nearly removed by ebullition, or, as recommended by Professor Clarke, by mixing the hard water with lime water, when the calcium combines with the excess of carbonic acid, which previously rendered the carbonate of calcium soluble, and is precipitated as carbonate (chalk), together with the carbonate originally present. This method removes, at the same time, much of the organic matter, and carries down suspended matter. The water is often made more palatable than before. The directions are:——For every degree of hardness on Clarke’s scale each 1000 gallons of water to be softened requires one ounce of quicklime. Slake the lime and work up to a thin cream with water and pour into the cistern, which already contains at least 50 gallons of water to be softened. Then add the remainder of the 1000 gallons in such a way as to stir up and mix uniformly with the contents of the cistern. In about three hours the milky water is clear enough for washing. After twelve hours’ rest the water is fit to drink. If the exact hardness of the water is not known, water may be added to the milk of lime till, on adding a drop of nitrate of silver to a cupful of the cistern water, the brown tint indicative of an excess of lime is replaced by a very faint yellow. 5. To save boilers from scaling, water intended for steam purposes is sometimes treated with lime to remove carbonates, and then the sulphate of calcium (which forms a very tenacious scale) is decomposed with baric chloride (Haen’s process). The precipitated mineral matter may also be prevented from forming a scale or fur by adding organic substances, such as potatoes, sound or otherwise, swedes, mangolds, or other vegetable. Oak bark, spent tan, sawdust; and their decoctions are efficacious on account of the tannic acid they contain, but they attack the boiler plates at the same time. Zinc suspended in the water is said to answer well. It has been recommended to polish the inside of the boiler plates with black lead or coat it with linseed oil and dissolved india rubber. Numerous chemical preparations, most of which do more harm than good, are also sold.

_Tests (Physical)._——1. To observe colour, stand in tall colourless glass cylinder on white ground. If very turbid allow to settle, and examine sediment by microscope for evidence of sewage contamination (linen fibres, hairs, epithelium) and for moving organisms. Slight turbidity is best noted by filling a clean quart flask and holding it towards the light with some dark object as a window pane between. Taste and odour most marked when the water is made lukewarm. 2. For poisonous metals add one drop of strong colourless ammonium sulphide to about 1000 grains of water in glass cylinder, and observe if liquid darkens. If the coloration or precipitate disappears on adding acid, it is iron; if it remains, lead or copper is present, either of which condemns the water. 3. For chlorine add couple of drops of nitric acid to a little of the water and a crystal or drop of solution of nitrate of silver. If the water turns very milky it is a bad sign; make, if possible, a comparative experiment with water of known composition. 4. The residuum, if any, of evaporation is impurity; if it be organic matter, smoke and a peculiar odour will be evolved, as the residue becomes dry and charred. 5. Neither litmus, syrup of violets, nor turmeric are discoloured or affected when moistened with pure water; if the first two are reddened it indicates an acid; if the litmus is turned blue or the turmeric is turned brown, an alkali is present. 6. If a precipitate is formed or a fur or crust deposited on the vessel during ebullition it indicates the presence of carbonates of calcium, magnesium, or iron. 7. Calcium salts produce a white precipitate with oxalate of ammonium. 8. The liquid filtered off from 7, on standing with phosphate of sodium and ammonium (microcosmic salt), gives a white precipitate if magnesium be present. 10. Tincture or infusion of galls turns water containing iron black. When this takes place both before and after the water has been boiled, the metal is present under the form of sulphate; but if it only occurs before boiling, then ferrous carbonate may be suspected, and it will be precipitated as a reddish powder by exposure to air and heat. 11. Ferrocyanide of potassium gives a dark blue precipitate in water containing a ferric salt; and a white one, turning blue by exposure to the air, in water containing a ferrous salt. 12. If sulphuric acid be run into water and allowed to cool, and a crystal of sulphate of iron dropped into the water, a dark brown cloud round the crystal indicates nitrates; the bleaching of indigo added to the hot mixture of equal parts water and pure oil of vitriol also indicates the presence of these salts. 13. Sulphuric acid or sulphates is indicated by a soluble salt of barium throwing down a white precipitate insoluble in nitric acid.

_Water, Quantitative Analysis of._——The quantitative analysis of potable water is confined to the following: total residue, hardness temporary and permanent, chlorine, ammonia, nitrates and nitrites, and organic matter.

Of these, all but the first two are intended to throw light on the organic contamination of the water. Chlorine, ammonia, and nitrates and nitrites are in themselves innocuous substances, but are estimated because they supplement the somewhat imperfect information obtained from the organic matter itself. A sewage-polluted supply being an agent in propagating zymotic diseases, a knowledge of the source of the organic matter in a water is of the highest importance.

Before passing to the mode of estimating the above items it may be desirable to explain the object of each analysis and the interpretation which may be placed on the results.

_Total solid residue_ includes all the substance, organic or mineral, dissolved in the water. Everything beyond the two gases which enter into the combination of the water being useless, the ‘residue’ of a water is sometimes called the ‘total solid impurity.’ The less residue left by a water on evaporation the better, but a water need not be objected to for drinking purposes till the residue reaches 40 grains per gallon. For raising steam a water should not contain more than 20 grains, and should be, if possible, much less.

_The hardness_, or soap-wasting power of a water, is chiefly determined on economic grounds. Unless the hardness is very excessive, the hardness or softness of the water does not appear to materially affect the health of the consumer. Hardness is caused by salts of lime and magnesia. If the property of hardness be caused by the presence of bicarbonates of the above substances, the water is said to be ‘temporarily’ hard, for by boiling or adding lime as above described, the hardness may be reduced without affecting the potability of the supply; but when the hardness is due to calcium or magnesium sulphates it is called ‘permanent’ hardness, for it is not then practicable to remove the hardening ingredients without adding some more objectionable substance. The average hardness of the four classes of pure water is shown in the analyses given above. Thames water has a total hardness of 15°, Loch Katrine water, as supplied to Glasgow, 0·70, on Clarke’s scale.

_Chlorine._——Except in places near the sea, or in salt-bearing strata, an unpolluted water does not contain more than the merest trace of chlorine. Sewage, however, contains a large quantity of chlorine as sodic chloride (common salt) derived from the salt used in cooking, &c. Hence a mixture of sewage with water becomes known by the quantity of chlorine present. It is not safe to drink a water containing such an excessive quantity of chlorine as 4 grains per gallon. The chlorine in Ullswater and Thames water is ·7 and 1·1 grains per gallon respectively. Sewage has about 8 grains on the average.

_Ammonia._——This determination acquires significance because it is one of the early substances produced by the decomposition of animal matter. It therefore indicates, when present in large quantities, _recent_ contamination by sewage. Rain always contains a small amount of ammonia, and deep wells occasionally show ammonia derived from the reduction of nitrates by the oxygen-seeking organic matter. The above inferences must, therefore, be applied with caution.

_Nitrates and Nitrites_ result from the oxidation of animal matter. Vegetable substances, under like conditions, yield none or but mere traces of these compounds. The presence of nitrates is a most unfavorable sign in a shallow well or river water, because the conditions to which these waters are subjected are so variable that there is a constant liability of the purifying processes diminishing, and allowing the sewage, now only represented by innoxious nitrates, to appear in its dangerous, unoxidised condition.