Part 153

=Essence, Volatile (Ammoniacal).= _Syn._ PUNGENT AMMONIACAL ESSENCE, AROMATIC AMMONIACAL E.; ESSENTIA VOLATILIS, E. V. AMMONIACALIS, E. V. AROMATICA, &c., L. _Prep._ 1. Oil of cinnamon, 6 drops; otto of roses, 12 drops; oil of cloves, 1 fl. dr.; essence of bergamotte, 2 fl. dr.; oil of lavender (Mitcham), 4 fl. dr.; essence of musk, 5 fl. dr.; liquor of ammonia (strongest), 1 pint; mix in a cold place, and shake the bottle until the whole is combined.

2. Essence of violets and oil of cinnamon, of each 12 drops; neroli, essence of jasmine, and otto of roses, of each 1/2 dr.; oil of lavender, 1 dr.; essence royale and essence (oil) of bergamotte, of each 2-1/2 dr.; liquor of ammonia (strongest), 1 pint; as the last.

3. Oils of lemon and bergamotte, of each 5 fl. dr.; oil of lavender, 1-1/2 fl. dr.; otto of roses, 1 fl. dr.; oils of cassia, neroli, cloves, and cedrat, of each 1/2 fl. dr.; oil of sandal wood, 15 drops; liquor of ammonia (strongest), 1 pint.

4. Essence of bergamotte, 6 fl. dr.; oil of lavender, 4 fl. dr.; oil of cloves, 3 fl. dr.; oil of cassia, 1-1/2 fl. dr.; oil of verbena (lemon-grass), 1 fl. dr.; otto of roses, 30 drops; liquor of ammonia, 18 fl. oz.

5. (Redwood.) Oil of bergamotte, 3 oz.; essence of lemons, 2 oz.; oil of lavender, 6 dr.; essence of jasmine, 4 dr.; oil of sassafras, 3 dr.; oil of neroli, 2 dr.; otto of roses, 1-1/2 dr.; oil of origanum and essence of ambergris, of each 1 dr.; musk, 20 gr.; macerate for a week, and decant the clear portion. It is added to the strongest liquor of ammonia in proportion of 1-1/2 oz. to the pint.

_Obs._ The above are used to fill smelling-bottles. They are all very fragrant and refreshing.

=Essence, Ward's.= See ESSENCE HEADACHE.

=Essence of Water-fen'nel.= _Syn._ ESSENTIA PHELLANDRI AQUATICI, E. F[OE]NICULIS A., L. _Prep._ (Cottereau.) Water-fennel seeds (fine-leaved water-hemlock, bruised), 1 oz.; proof spirit, 4 fl. oz.; digest. Narcotic and pectoral.--_Dose_, 5 to 25 drops, combined with bark; in phthisis, &c.

=Essence, Westphalian.= ESSENCE OF SMOKE, E. OF WOOD-SMOKE, CAMBRIAN ESSENCE, SMOKING FLUID; ESSENTIA FULIGINIS, &c., L. _Prep._ 1. Crude or empyreumatic pyroligneous acid, 1 pint; sugar colouring, 2 oz.; dissolve, and in a week decant the clear portion.

2. Tar, 3 dr.; sugar colouring, 2 oz.; hot crude pyroligneous acid, 1 pint; agitate constantly for 1 hour, and after repose decant the clear portion.

3. Acetic acid (Ph. L.), 1 pint; creasote, 5 dr.; mix. White.

4. Barbadoes tar, 1/4 oz.; burnt sugar and common salt, of each 1 oz.; strong pickling vinegar, 3/4 pint; port or elder wine, 1/4 pint; digest as before. Inferior to the preceding. Used to impart a smoky flavour to meat, fish, &c., by brushing it over them, or adding a little to the brine in which they are pickled.

=Essence of Worm'wood.= _Syn._ ESSENTIA AMARA, E. ABSINTHII, L. _Prep._ 1. Extract of wormwood, 4 oz.; oil of wormwood, 1 oz.; rectified spirit, 1 pint; digest a week and filter. Tonic, stomachic, and vermifuge.--_Dose_, 10 drops to a teaspoonful.

2. (Van Mons.) Tincture of wormwood, 1 pint; salt of wormwood, 5 dr.; extract of wormwood, 1 dr.; digest as before.--_Dose_, 1/2 to 1-1/2 fl. dr.

=Essences, Fla''vouring.= _Syn._ CULINARY ESSENCES, SPICE E., ESSENCES FOR THE TABLE, &c. Those used by cooks, confectioners, liqueurists, &c., are all made by either dissolving 1 fl. oz. of the essential oil of the particular substance in 1 pint of rectified spirit, or by digesting 4 to 6 oz. of the bruised spice, or 5 to 10 oz. of the dried herb, in a like quantity (1 pint) of spirit. The first method is preferable, from being the least troublesome, and yielding the finest product. They are commonly labelled 'CONCENTRATED ESSENCE OF ----.' An inferior article, vended under the names of 'ESSENCES OF CULINARY HERBS,' 'CULINARY TINCTURES,' 'TINCTURES FOR KITCHEN USE,' &c., are prepared from half the above quantity of oil or spice, infused in a pint of proof spirit or British brandy. The principal compounds of this class are the essences of allspice, caraway, cardamoms, cassia, cayenne, celery seed, cinnamon, cloves, coriander seed, fennel, garlic, ginger, lemon peel, mace, marjoram, nutmegs, orange peel, peppermint, spearmint, sweet basil, and the like. The whole of these are employed to flavour soups, gravies, sweetmeats, pastry, wines, mulled wines, liqueurs, &c.

=Essences, Flower.= Those for which separate formulæ are not given in this work may most of them be made from the essential oil of the flowers and rectified spirit, as the last; or by digesting the flowers (crushed or bruised), 3 to 5 lbs., in proof spirit, 2 galls., for a few days, and then drawing over, by distillation, 1 gall. For the essences of those flowers which are not strongly odorous, the spirit thus obtained is distilled from a like quantity of flowers, a second, and a third time, or even oftener. The essences of other organic substances, whose fragrant principles are volatile, may be prepared in the same manner. A small quantity of some other odorous essence is frequently added to the product, to enrich or modify the fragrance. See FLOWERS and ESSENCES BY INFUSION.

=Essences, Fra'grant.= See FLOWER ESSENCES (_above_), ESSENTIA ODORATA, PERFUMERY, &c.

=Essences, Fruit.= See ESSENCES OF APPLE, PINE-APPLE, JARGONELLE, &c.

=Essences by Infu'sion.= This term, among perfumers, is commonly applied to those essences, eaux, and esprits, which are prepared by digesting the ingredients in the spirit used as the vehicle for the aroma, in opposition to those obtained by 'distillation,' or by 'contact,' or 'pressure.' Thus, the ESSENCES OF AMBERGRIS, MUSK, and VANILLA, are of this class.

=Essences, Vi'nous.= _Syn._ ESSENTIA VINOSA, L. These are prepared in a similar way to the wines (VINA) of the pharmacop[oe]ia, by using 8 times the usual quantity of ingredients, and the very strongest sherry wine. 1 fl. dr., added to 7 fl. dr. of wine or water (properly the first only), forms an extemporaneous imitation of the officinal VINA MEDICATA. Some of the above are largely used in dispensing, and by travellers. See LIQUOR and WINE.

=ESSENTIA BI'NA.= See COLOURING.

=Essentia, Odora'ta.= _Prep._ 1. Oil of lavender, 1 dr.; oils of cloves, cassia, and bergamot, of each 1/2 dr.; neroli, 20 drops; essence royale, 2 fl. dr.; rectified spirit, 1/2 pint; mix.

2. (Redwood.) English oil of lavender, 48 drops; oil of cloves, 32 drops; oil of orange peel, 16 drops; oil of bergamotte and sweet spirit of nitre, of each 8 drops; oil of yellow sandal-wood, neroli, and otto of roses, of each 2 drops; oil of cinnamon, 1 drop; rectified spirit, and essence of ambergris and musk, of each 1 oz.; honey water, 8 oz.; mix. Used as a perfume for the handkerchief, &c. The last form seems unnecessarily complicated and minute.

=Essentia Odorif'era.= _Prep._ 1. Grain musk and balsam of Peru, of each 10 gr.; civet, 4 gr.; oil of cloves, 5 drops; oil of rhodium, 3 drops; salt of tartar (dried by a dull-red heat and cooled), 1/2 dr.; rectified spirit (strongest), 2-1/2 fl. oz.; macerate for 14 days, and pour off the clear.

2. Oil of rhodium and balsam of Peru, of each 1/2 dr.; oil of cloves, 1 dr.; spirit of ammonia, 2 fl. dr.; essence of civet and vanilla, of each 2 fl. oz.; essence of musk, 5 fl. oz.; neroli, oils of lavender, verbena, and cassia, of each 6 drops. As last. Both are very pleasant, durable, and powerful perfumes for personal use.

=ESSENTIAL OIL.= See OIL (Volatile).

=ESSENTIAL SALT OF BARK.= See BARK and =Extract=.

=ESSENTIAL SALT OF LEMONS.= _Syn._ SALT OF LEMONS; SAL LIMONUM, L. The preparation sold under this name is made by mixing cream of tartar (bitartrate of potassa) with twice its weight of salt of sorrel (quadroxalate of potassa), both in fine powder. It is used to remove fruit stains, &c., from linen, by rubbing a little of it on the part moistened with warm water. It is poisonous, if swallowed in quantity.

=ETCH'ING.= A species of engraving, in which the design is formed on the plate by the action of an acid, or some other fluid, instead of being cut out by the graver.

_Proc._ In the ORDINARY PROCESS OF ETCHING the plate is covered with 'etching ground' (an acid-resisting varnish), and the design is scratched on the metal through the ground, by means of a pointed tool of steel called the 'etching needle' or 'point.' A border of wax is then placed round the plate, and the 'biting' fluid poured on, and allowed to remain till the 'lights' or finest portions of the design are sufficiently 'bitten in,' The etching fluid is then poured off, the plate washed, and the light parts 'stopped out' with Brunswick black or other varnish; the solvent is again poured on, and allowed to remain until the finest portion of the exposed lines are sufficiently deep, when the acid is again poured off, and the whole process is repeated till the very darkest lines or shadows are sufficiently 'bitten in,' The plate is then cleaned, and is ready to be printed from. Occasionally the etched design receives a few finishing touches with the 'graver.'

There are several varieties of etching, of which the following are the principal:--ETCHING WITH A SOFT GROUND, when a coating of lard or tallow is employed, and the design is drawn on a piece of paper, laid evenly on the ground, by which means the fatty matter adheres to the paper, on the parts pressed on by the point or pencil, and the copper beneath becomes exposed, and is then acted on by the acid. The effect resembles that of chalk or pencil drawings.--STIPPLING, or executing the design in dots instead of lines.--AQUATINTA or AQUATINT, a mode of etching on copper for producing an effect resembling a drawing in Indian ink. It is performed by sifting powdered asphaltum or lac resin on the plate, previously slightly greased, and, after shaking off the loose powder, gently heating it over a chafing dish; on cooling, the lights are covered with turpentine varnish coloured with lampblack, by means of a hair pencil, and a rim of wax being placed round the plate, a mixture of 'aquafortis' and water is poured on it, and allowed to remain for 5 or 6 minutes, when it is poured off, the plate dried, and recourse had to the pencil as before. The process of 'stopping' and 'etching' is repeated again and again, until the darkest shades are produced. Sometimes, instead of using asphaltum, an alcoholic solution of shell-lac or gum mastic is poured over the plate, placed in a slanting direction; this varnish forms a film, which, on drying, leaves innumerable cracks or minute fissures through which the acid acts on the plate. The fineness or coarseness of the grain depends entirely upon the condition of the powdered asphaltum, or on the quantity of matter dissolved in the spirit employed to form the ground.

The fluids employed for 'biting in' the designs vary considerably, almost every artist having his own receipt. Aquafortis, more or less diluted, is, however, generally employed for COPPER, and this, with the addition of pyroligneous acid, for etching on STEEL; but any fluid that rapidly dissolves the metal may be used for the purpose. The 'etching ground' may be formed of any substance capable of resisting the action of the etching fluid, and which is, at the same time, sufficiently soft to allow of the free use of the needle or point, and sufficiently solid to prevent an injury to the design during the 'scratching in,'

In ETCHING ON GLASS, the ground is laid on, and the design 'scratched in' in the usual way, when liquid hydrofluoric acid is applied, or the glass is exposed to the action of hydrofluoric acid gas. The former renders the surface of the etching transparent, the latter opaque. A simple modification of the process is to wet the design with sulphuric acid, and then to sprinkle on some finely pulverised fluor spar (fluoride of calcium), by which means hydrofluoric acid is set free and attacks the glass. This method may be very easily applied to the graduation of glass vessels, thermometer tubes, &c.

ETCHING ON GLASS BY ELECTRICITY. Planté ('Ann. Chem. Phys.' [5], xiii, 143-144). The author had previously drawn attention to the fact that when an electric current is passed through saline solutions in glass vessels, platinum wire serving as electrodes, the glass is immediately attacked, and he therefore proposes the following method for etching on glass:

The surface of the glass to be engraved is coated with a concentrated solution of potassium nitrate, and beneath the layer of liquid a platinum wire, connected with one of the poles of a battery, is stretched across the plate. With the other pole is connected another platinum wire, the whole of which, except the point, is insulated; with this the designs are drawn on the glass, which is engraved wherever the wire comes in contact with it, flashes of light being emitted at the same time.

The depth of engraving depends on the rate at which the platinum wire moves; the slower the rate the deeper the line.

A RAPID METHOD OF ETCHING ON IRON OR STEEL, capable of very general application, is as follows:--"The metal is warmed until it is capable of melting a piece of beeswax, or 'etching ground,' which is then carefully rubbed over it, so as to form a thin and even coating; when cold, the design is 'scratched in' in the common way; a little powdered iodine is then sprinkled on the exposed parts, and at the same time a few drops of water are added, and the two worked into a liquid paste with a camel-hair pencil. The paste is then moved about over the intended etching, for a period varying from one to five minutes, according to the depth of the lines required to be produced. Afterwards the whole is removed, and reapplied, &c., as with the usual etching fluids. The same etching-paste, by being kept for a few days, again acquires the property of dissolving iron, and may be used again and again; but independently of this, the iodide of iron formed during the process, if rapidly evaporated to dryness in a clean iron vessel by a moderate heat, and placed in stoppered bottles, will sell for more than the original cost of the iodine. To travellers and amateurs who amuse themselves with the delightful art of etching, iodine, from its portability and convenience, will, doubtless, prove invaluable. We have adopted it with considerable success, and have found it especially useful in marking surgical instruments, razors, and other edge tools. We published this method many years ago. Several parties have since availed themselves of our suggestions and formulæ, but without the slightest acknowledgment of the source from which they obtained them." (A. J. Cooley.)

=Etching, Electro-.= This mode of etching, which is in many respects superior to the ordinary mode, is based upon the destructive action of certain 'anions' during 'electrolysis.'[281] If two plates of copper be connected with the opposite ends of a voltaic battery, and placed in a vessel containing very dilute sulphuric acid, the plate connected with the copper of the battery will be attacked by the anion oxygen which is released during the decomposition of the acid. This destructive action can be localised at pleasure by covering certain parts of the plate with a protecting stratum of varnish, ordinary 'etching ground' for instance. In the practice of electro-etching, the drawing is 'scratched in' in the usual way through an ordinary ground; a stout wire is then soldered to the plate, and this, as well as the back of the plate, is coated with sealing-wax varnish. Thus prepared, the plate is placed in a suitable 'decomposition cell' opposite a plate of somewhat similar size, and the two are connected respectively with the copper and zinc of a 'Daniell's cell,' or the silver and zinc of a 'Smee's cell.'[282] After about ten minutes the plate is removed, washed, and dried; and when the 'fine work' has been stopped out with Brunswick black, it is returned for another space of ten minutes. By alternately exposing the plate to the action of the decomposing fluid, and 'stopping out' parts of the work, the required gradation in tints is obtained. The exact duration of the various exposures, as well as their number, must, of course, be regulated by circumstances. See ETCHING FLUIDS (_below_).

[Footnote 281: See ELECTROLYSIS and ELECTROTYPE, pages 428 and 429.]

[Footnote 282: See VOLTAIC ELECTRICITY.]

=Etching Fluids.= 1. (For COPPER.)--_a._ From 'aquafortis,' 2-1/2 fl. oz.; water, 5 fl. oz.; mix.

_b._ To the last add of verdigris, 1 oz.; water, 2-1/2 fl. oz.; dissolve. For light touches.

_c._ (EAU FORTE,--Callot and Piranesi.) Alum, sal-ammoniac, sea salt, and verdigris, of each 4 oz.; vinegar (pyroligneous acid), 8 fl. oz.; water, 16 fl. oz.; mix, dissolve, boil for 1 or 2 minutes in a glazed or stoneware vessel, cool, and decant the clear portion. Used as the last.

_d._ Water acidulated with sulphuric acid. Used in the process of electro-etching.

2. (For STEEL.)--_a._ From iodine, 1 oz.; iron filings or wire, 1/2 dr.; water, 4 fl. oz. It must be kept in a stoppered bottle, until required for use.

_b._ From iodine, 3 dr.; iodide of potassium, 1 dr.; proof spirit, 1 fl. oz.; water, 2 fl. oz. As the last.

_c._ (Mr Turrel.) Pyroligneous acid, 4 fl. oz.; alcohol (rectified spirit), 1 fl. oz.; mix, and add of nitric acid or double aquafortis (sp. gr. 1·28), 1 fl. oz.

_d._ From hydrochloric acid, 5 parts; water, 95 parts; mix, and add the liquid to a solution of chlorate of potassa, 1 part, in water, 50 parts.

_e._ A solution of common salt. Used in the process of electro-etching.

=Etching Ground.= _Syn._ ETCHING VARNISH. _Prep._ 1. Beeswax, 5 parts; linseed oil, 1 part; melted together.

2. (Callot's HARD VARNISH, FLORENTINE V., FLORENCE V.) From linseed oil and mastic, equal parts, melted together.

3. (Callot's SOFT VARNISH.) From linseed oil, 4 oz.; gum benzoin and white wax, of each 1/2 oz.; boil to two thirds.

4. (Lawrence.) White wax, 2 oz.; black pitch and Burgundy pitch, of each 1/2 oz.; melt, add by degrees, of powdered asphaltum, 2 oz.; and boil together, until a piece, when thoroughly cold, will break by being bent double 2 or 3 times between the fingers; next pour it into warm water, make it into small balls, and place each of them in a piece of taffety for use.

_Obs._ The preceding compositions are applied to the surface of the plates, previously made sufficiently warm to melt them easily, their even diffusion being promoted by dabbing them with a wad of cotton. Those that are white are then generally blackened on the surface by skilfully passing them over the smoky flame of one or more candles, by which the marks of the etching point on the bright metal are rendered the more visible.

=E'THER.= _Syn._ OXIDE OF ETHYL. Described under ETHYL, OXIDE OF. Several substances are known under the name of ethers besides the true ethers or salts of ethyl, and are given below.

=Ether of Canthar'ides.= _Syn._ ÆTHER CANTHARIDALIS, L. _Prep._ ([OE]ttinger.) From powdered cantharides, 1 part; ether, 2 parts; digested together for 3 or 4 days, and the tincture expressed. Used as a vesicant, &c.

=Ether, Chlo''ric.= This name was applied by Dr T. Thomson to the CHLORIDE OF OLEFIANT GAS, or 'DUTCH LIQUID,' and afterwards, by Guthrie and Silliman, to CHLOROFORM, which they took for an alcoholic solution of chloride of olefiant gas. It now forms one of the synonyms of chloroform. The medicinal 'CHLORIC ETHER' of the shops is a solution of chloroform, 1 part, in rectified spirit 8 parts; of which the _dose_ is 20 or 30 drops in water, as an antispasmodic and anodyne. See CHLOROFORM.

=Ether, Chlorinet'ted.= Formed by the action of dry chlorine on pure ether. When the action is long continued, a heavy, oily product (BICHLORINETTED ETHER), smelling like fennel, is formed. By the still further action of chlorine, aided by sunlight, a white, crystalline substance (PENTACHLORINETTED ETHER), a compound resembling sesquichloride of carbon, is obtained.

=Ether, Cu''preous.= _Syn._ TINCTURA CUPRI CHLORIDI ÆTHEREA, L. _Prep._ (Van Mons.) Sulphate of copper, 6 parts, and chloride of barium, 5 parts, are triturated together, and the mixture digested in ether, 3 or 4 parts, until all the chloride of copper is dissolved.--_Dose_, 2 to 5 drops; in epilepsy, &c.

=Ether, Methy'lic.= _Syn._ OXIDE OF METHYL, WOOD-ETHER, METHYL-ETHER; ÆTHER METHYLICUS, L. _Prep._ From wood spirit, 1 part; concentrated sulphuric acid, 4 parts; mix in a retort, apply heat, pass the evolved gas (methylic ether) through a little strong solution of potassa, and then collect it over mercury. See METHYL.

=Ether, Spirits of Nitrous.= See SPIRITS.

=Ether, Washed.= _Syn._ ÆTHER LOTUS, L. Ordinary ether, agitated first with 2 or 3 times its volume of distilled water, and a few grains of carbonate of potassa, or a few drops of milk of lime; and after decantation, again agitated with a like quantity of water only. Used for inhalations. For other purposes the washed ether is afterwards digested on chloride of calcium, to deprive it of retained water.

=E'THERIN.= _Syn._ CAMPHOR OF OIL OF WINE. A volatile, white, crystalline substance, deposited by light oil of wine when left in a cold situation for some time. It is isomeric with etherole, and received its name from the assumption of its being the base of the ethereal compounds. According to this hypothesis, ether is a hydrate of etherin. Etherin forms brilliant prisms and plates; is tasteless; soluble in alcohol and ether; fuses at 230° Fahr., and boils at 500° Fahr.; and is a little lighter than water. The crystals are purified by pressure between the folds of bibulous paper, solution in ether, and evaporation.

=E'THEROLE.= The yellowish, oily liquid, forming the residual portion of light oil of wine, after it has deposited its etherin. It is lighter than water; is freely soluble in both alcohol and ether; and has a rather high boiling-point. See ETHERIN and OIL OF WINE.

=ETHION'IC AC'ID.= _Prep._ An alcoholic solution of the crystals of sulphate of carbyle is diluted with water, the whole neutralised with carbonate of baryta, the filtered liquid evaporated by a very gentle heat to a small bulk, and a large quantity of alcohol added; the precipitate (ethionate of baryta) is treated (cautiously) with dilute sulphuric acid (avoiding excess), by which the baryta is withdrawn, and ethionic acid left in solution.

_Prop., &c._ Ethionic acid closely resembles sulphovinic acid. It is decomposed by heat. Its salts (ethionates), however, differ completely from the sulphovinates. They are all soluble in water, and are said to be anhydrous. The ethionates of ammonia, potassa, and soda crystallise readily; those of lead, baryta, lime, and the other earths are uncrystallisable. See ISETHIONIC ACID, and _below_.

=ETHION'IC ANHY'DRIDE.= _Prep._ Pure and dry olefiant gas is passed over anhydrous sulphuric acid ('sulphuric anhydride') contained in a U-shaped tube.

_Prop., &c._ When thus produced, it is in white, milky crystals, which speedily deliquesce in the air, giving rise to ethionic acid. It is similar in appearance, and probably identical with, 'sulphate of carbyle,' which results from the absorption of the vapour of anhydrous sulphuric acid by absolute alcohol.

=E'THIOPS.= _Syn._ ÆTHIOPS, L. A name given by the older chemists to several black powders on account of their colour, and still occasionally employed in medical works.

=Ethiops, Graphi'tic.= _Syn._ ETHIOPS OF PLUMBAGO; ÆTHIOPS GRAPHITICUS, L. From plumbago, 2 parts; quicksilver, 1 part; triturated together until the globules disappear.--_Dose_, 5 to 10 gr.; in herpes, and some other obstinate skin diseases.

=Ethiops, Martial.= Black oxide of iron, prepared by keeping iron filings under water, and occasionally shaking them. It is washed with water, dried as quickly as possible, and preserved from the air, to prevent further oxidation. Formerly much esteemed as a tonic.