Part 106
The above proof-solution is next poured into 12 two-oz. vials, of exactly equal diameters, to the amount of 1/9th of their capacity; these are filled up with bleaching liquid of various strengths; the first at 1/12th of a degree of Twaddell, the second 2/12ths, and so on up to 12/12ths of 1°. They are then well corked up, and, after agitation, arranged side by side on a tray, furnished with holes to receive them. (See _engr._) To ascertain the strength of an unknown sample of bleaching liquor, the proof-solution of iron is put into a phial, exactly similar to the 12 previously used, and in precisely the same proportion (1/9th). The phial is then filled up with the bleaching liquor, well shaken, and placed beside that one of the 12 already prepared which it most resembles in colour. The number on that phial expresses the strength of the sample under examination, in twelfths of a degree of Twaddell's hydrometer.
_Obs._ The preceding method is admirably suited for weak solutions, such as are employed for bleaching textile fabrics, and is well adapted (from its simplicity) to the purposes of practical men. Indeed, it is quite astonishing to see with what ease and accuracy it is applied by unlettered operatives. This gives it great practical value. It has been for some time in extensive use in the bleaching houses of Scotland.
TABLE _exhibiting the quantity of Bleaching Liquid, at 6° on_ TWADDELL'S _scale_ (_sp. gr._ 1·030), _required to be added to a weaker liquor, to raise it to the given strengths. Adapted from_ MR CRUM'S _table by_ MR COOLEY.
| | Proportions required. Strength | Required |----------------------- of Sample | Strength. | Given | Liquor in 1/12°. | | Sample. | at 6°. -----------+-----------+-----------+----------- | | Parts. | Part. Water. | 8/12° | 8 | 1 1 | " | 9-1/4 | 1 2 | " | 11 | 1 3 | " | 13-1/2 | 1 4 | " | 17 | 1 5 | " | 23 | 1 6 | " | 35 | 1 7 | " | 71 | 1 Water. | 6/12° | 11 | 1 1 | " | 13-1/2 | 1 2 | " | 17 | 1 3 | " | 23 | 1 4 | " | 35 | 1 5 | " | 71 | 1 Water. | 4/12° | 17 | 1 1 | " | 23 | 1 2 | " | 35 | 1 3 | " | 71 | 1 Water. | 3/12° | 23 | 1 1 | " | 35 | 1 2 | " | 71 | 1 ------------------------------------------------
According to Mr Crum, the range of strength within which cotton is "safe" is very limited. A solution at 1° of Twaddell's scale (sp. gr. 1·005) is not more than safe, while one at 1/2° is scarcely sufficiently strong for the first operation on stout cloth, unless it is packed more loosely than usual.
_Gay-Lussac's Indigo Process._ One part of the best indigo is dissolved in 9 parts of strong sulphuric acid by the aid of a gentle heat; this solution is then mixed with distilled water, in such proportion that 1 volume of chlorine gas shall exactly decolour 10 volumes of this solution. Each measure so decoloured is called a degree, and each degree is divided into fifths. 5 gr. of the best chloride of lime, dissolved in 500 gr. measures of water, possess the above power, and indicate 10° or proof; or in other words, will decolour 10 times its volume of the indigo solution.
_Obs._ This method of chlorometry is objectionable, and liable to error, from the indigo solution altering by keeping. When, however, the proper precautions are used, it may be safely trusted for weak bleaching liquors.
_Arsenious Acid Process._ This depends on the conversion, by oxidation, of arsenious acid into arsenic acid, in the presence of chlorine and water.
To prepare the test-liquor, pure arsenious acid, 100 gr., are dissolved in about 4 fl. oz. of pure hydrochloric acid (free from sulphurous acid), and the solution diluted with water until, on being poured into a graduated 10,000 grains-measure-glass, it occupies the volume of 7000 grains measure marked on the scale. Each 1000 grains measure of this liquid now contains 14·29 gr. of arsenious acid; corresponding to 10 gr. of chlorine, or 1/10th gr. of chlorine for every division or degree of the scale of the chlorometer.
100 gr. of the chloride of lime to be examined are next dissolved in water as before, and poured into a tube graduated up to 2000 grains measure. The whole is now well shaken, in order to obtain a uniformly turbid solution, and half of it (1000-grains-measure) transferred to a graduated chlorometer, which is, therefore, thus filled up to 0°, or the zero of the scale, and contains exactly 50 gr. of the chloride of lime under examination; whilst each degree or division of the scale contains only 1/2 gr.
1000 grains measure of the arsenious acid test-liquor are now poured into a glass beaker, and a few drops of solution of sulphate of indigo added in order to impart a faint but distinct blue colour to it; the glass is then shaken so as to give a circular movement to the liquid, and whilst it is whirling round, the chloride-of-lime solution from the chlorometer is gradually and cautiously added, until the blue tinge given to the arsenious acid test-liquor is destroyed; care being taken to stir the mixture well during the whole process, and to stop as soon as the decolorisation is completed.
Let us suppose now that, in order to destroy the blue colour of the 1000 grains measure of the arsenious acid test-liquor, 90 divisions or degrees of the chloride-of-lime solution have been employed. These 90 divisions, therefore, contained the 10 gr. of chlorine required to destroy the colour of the test-solution; and since each division represents 1/2 gr. of chloride of lime, 45 gr. of chloride of lime (10 gr. of chlorine) were present in the 90 divisions so employed, from which the per-centage strength may be ascertained. For--
45 : 10 : : 100 : 22·22
The chloride of lime examined, therefore, contained 22-1/4 per cent, (nearly) of chlorine.
_Obs._ This method is extremely simple and trustworthy when properly employed; but to ensure accuracy, certain precautions must be adopted. Instead of pouring the test-liquor into the solution of the sample (as in alkalimetry), the solution of the sample must be poured into the test-liquor.
Vogel found that in a normal solution of arsenious acid that had been prepared for using in the above process, half the quantity of the arsenious acid became oxidised to arsenic acid in the course of about a year. He therefore recommends that the standard solution, if kept for some time, should be tested by a magnesium salt. The formation of a precipitate would show the solution had undergone such a change, as to render it unfit for volumetric estimations.
_Penot's Process._ This is a modification of the previous process. For the arsenious acid solution arsenite of soda is substituted, and for the indigo solution a colourless iodised paper, which is turned blue by the smallest quantity of free acid. The paper is prepared in the following manner:--1 gram of iodine, 7 grams of carbonate of soda, 3 grams of starch, and a quarter of a litre of water are mixed. When the solution becomes colourless it is diluted to half a litre; in this fluid, white paper is soaked. The arsenical fluid is prepared by dissolving 4·44 grams of arsenious acid, and 13 grams of crystallised carbonate of soda in 1 litre of water. This solution is added by means of a burette to the solution of chloride of lime intended to be tested (10 grams of the sample to 1 litre) the completion of the reaction being known by the paper remaining uncoloured.
Lunge says that the same piece of moist iodine test paper may be made use of repeatedly, since the spots produced by testing usually disappear after about twenty-four hours if exposed to the air. The paper must, however, be kept away from dust.
_Wagner's Process._ This method is based upon the fact that a solution of chloride of lime separates the iodine from a weak (1 to 10) and slightly acidified iodide-of-potassium solution, the iodine being quantitatively estimated by means of hyposulphite of soda:--
Iodine 21, } {Iodine of sodium, 2NaI, Hyposulphite of } yield {Tetrathionate of sodium, Na_{2}S_{4}O_{6}, soda, 2Na_{1}SO_{3} } {Water, 5H_{2}O. +5H_{2}O,
The test is performed as follows:--100 c. c. =1 gram of bleaching-powder solution, obtained by dissolving 10 grams of chloride of lime in 1 litre of water, are mixed with 25 c. c. of solution of iodide of potassium acidified with dilute hydrochloric acid. The resulting clear, deep brown-coloured solution is treated with hyposulphite of soda solution until quite colourless. The hyposulphite of soda solution is composed of 24·8 grams of that salt to 1 litre of water; 1 c. c. of this solution neutralises 0·0127 grams of iodine, and 0·00355 grams of chlorine.
_Otto's Process._ This method is based upon the following data. Two molecular weights of protosulphate of iron when brought into contact with chlorine, in presence of water, and free sulphuric acid, give one molecule of persulphate of iron, and two molecules of hydrochloric acid, the process consuming one molecule of chlorine. Two molecules of crystallised sulphate of iron = 556, correspond to 71·0 of chlorine, or in other terms 0·7839 grams of the crystallised sulphate correspond to 0·1 gram of chlorine.
_Bunsen's Process._ This consists in adding iodide of potassium to the bleaching-powder liquor, acidulating the mixture with hydrochloric acid, and running the solution of arsenite of soda into it till only a yellow tint shows itself. A little starch paste is now added, and the arsenite solution cautiously introduced drop by drop, till the blue colour just disappears. The solutions must all be standardised. To preserve the starch paste Mohr advises the addition to it of a little chloride of zinc.
_Mr Davies_ uses glycerin as a solvent for the arsenious acid. He prepares a standard solution as follows:--13·95 grains of arsenious acid in 40 c. c. of glycerin and fitted up to 1 litre. Every c. c. corresponds to 0·1 grain of chlorine. Indigo sulphate solution is used as an indicator, and the bleaching liquor is run into the glycerin solution until the blue colour of the latter is changed to a brownish yellow.
_Dr Ure's_ as follows:--Liquor of ammonia, of a known strength, tinged with litmus, is added to a solution of a given weight of the chloride under examination, until the whole of the chlorine is neutralised, which is known by the colour being destroyed. From the quantity of ammonia consumed the strength of the sample is estimated.
The value of bleaching powder is estimated in England, America, and Germany by degrees corresponding to the per-centage of available chlorine contained in a sample of chloride of lime by weight; but in France the degrees denote the number of litres of chlorine gas at 0° c. and 760° Mm. Bar., which 1 kilo of bleaching powder can evolve. In the following table the chlorometrical degrees of France and England are contrasted:--
French. English. 63 20·02 65 20·65 70 22·24 75 23·83 80 25·42 85 27·01 90 28·60 100 31·80 105 33·36 110 34·95 115 36·54 120 38·13 125 39·72 126 40·04
The per-centage may be calculated by multiplying the French degrees by the coefficient 0·318.
=CHLOROCARBONIC ACID.= (COCl_{2}). _Syn._ PHOSGENE GAS, CARBONIC OXYDICHLORIDE. This compound may be produced by the direct combination of equal volumes of carbonic oxide and chlorine gases under the influence of sunlight (whence its name of "phosgene gas"), when the mixture gradually becomes colourless, and contracts to half its original volume. Chlorocarbonic acid has a peculiar pungent smell, and fumes strongly when exposed to moist air, the moisture of which it decomposes, producing at the same time hydrochloric and carbonic acids.
It is sometimes employed in chemical research for the removal of hydrogen from organic compounds, and the substitution of carbonic oxide, or its elements for the hydrogen.
=CHLOROPHYLL.= The green colouring matter contained in the leaves, stalks, unripe fruit, and juices of most plants.
=CHLORO'SIS.= _Syn._ GREEN SICKNESS. A disease which principally affects young unmarried females.
_Symp._ Languor, listlessness, fatigue after the least exercise, palpitation of the heart, flatulency, indigestion, acidity of stomach and bowels, constipation (generally), appetite for unnatural food, general debility, &c. As the disease advances, the skin at first pale, assumes a peculiar greenish tint, the respiration becomes affected, the feet and legs swell, and various organic affections of the viscera ensue. During the early stages of this disease the catamenia are usually pale and scanty, and return at irregular intervals, and as it progresses they disappear altogether.
_Treat._ This should be tonic and restorative. That recommended under ANÆMIA may be adopted with advantage. See also APPETITE, ATROPHY.
=Chlorosis, Electuary for--Female Electuary.= A greenish-black thick syrup, consisting of sugar, bayberries, carbonate of iron, iron filings, and water. (Buchner.)
=Chlorosis Powder--Female Powder=--consists of a mixture of anise, sugar, and 14 per cent. of iron filings. (Wittstein.)
=Chlorosis Powder--Female Powder=, according to Schott and Strauss, is a mixture of violet root, gum Arabic, and a tasteless green powder with 33 per cent. of steel filings. According to Hager, it is composed of 2 parts ferri pulvis, with 3 parts powdered sweet-flag root.
=Chlorosis Powder--Female Powders.= Steel filings, starch powder, and knot grass, of each 1 part, Florentine orris root, 4 parts.
=Chlorosis Powder--Female Powders.= A mixture of 1 part steel filings and 2 parts of a vegetable powder composed of gum Arabic, Florentine orris, knot grass, &c. (Egb. Hoyer.)
=Chlorosis Water= (Dr Ewich) contains in 10,000 parts 11 of sodium carbonate, 9 of sodium chloride, 1-1/2 sodium sulphate, 7 calcium carbonate, and 1·2 iron carbonate with an excess of carbonic acid. (Hager.)
=CHLOROUS ACID.= HClO_{2}. _Syn._ ACIDUM CHLORO'SUM, L. _Prep._ From chlorate of potassium, 4 parts; arsenious anhydride, 3 parts; nitric acid, 12 parts; (diluted with) water, 4 parts; heated together in a glass flask, furnished with a bent tube, and placed in a water bath. It must be collected in the same way as chlorine, or passed into water, when it forms a solution of chlorous acid.
_Prop., &c._ Chlorous acid is a greenish-yellow gas, non-condensable by a freezing mixture of salt and ice, but liquefiable by extreme cold. The aqueous solution undergoes gradual decomposition, yielding chloric acid and chlorine. Chlorous acid possesses powerful oxidising and bleaching properties; with the bases it forms salts called CHLORITES. These are all soluble in water, and bleach like the acid. They may be recognised by the evolution of chlorous acid gas when acted on by an acid. The use of the arsenious acid is to deoxidise the nitric acid employed in the process. Tartaric acid, or other deodorising agent, may be substituted for it.
=CHOC'OLATE.= _Syn._ CHOCOLA'TA, L.; CHOCOLLATI, Mexican; CHOCOLAT, Fr. A beverage or paste made from the roasted seeds of the _Theobroma Cacao_, or COCOA. Strictly speaking, the term "chocolate" is applicable to all genuine preparations of cocoa, but it is now generally used to distinguish those which contain sugar, and, commonly, flavouring substances. Of late years great attention has been paid to the manufacture of chocolate in England; our principal makers now import the finest descriptions of cocoa, and produce varieties of the manufactured article which are scarcely inferior to those of their French rivals. The different kinds of cocoa, and the processes of roasting, sweating, &c., are described under COCOA, to which article we refer the reader also for particulars respecting the chemistry of chocolate.
_Prep._ The cocoa nibs[245] are ground in a mill consisting of stone or metal rollers, which are usually heated either by charcoal fires or by steam, so as to soften or melt the natural fat.[246] The warm, smooth paste which passes from the mill is then placed in a mixing mill, and incorporated with refined sugar, and usually vanilla or other flavouring substance. The trituration is continued until the whole paste is converted into an entirely homogeneous mass, which is finally shaped, by means of suitable moulds, into various forms, as blocks, loaves, tablets, lozenges, &c.
[Footnote 245: The bruised, roasted seeds, freed from husk and membrane.]
[Footnote 246: Cacao- or cocoa-butter.]
_Obs._ Chocolate, prepared as above, without the addition of aromatics, is known in the trade as PLAIN CHOCOLATE. The Spaniards flavour it with vanilla, cloves, and cinnamon, and frequently scent it with musk and ambergris. With these additions it is termed SPANISH CHOCOLATE. In general, they add too large a quantity of the last four articles. The Parisians, on the contrary, use little flavouring, and that principally vanilla. They employ the best kinds of cocoa, and add a considerable quantity of refined sugar. So prepared, it is called FRENCH CHOCOLATE.
_Proportions._ 1. FRENCH CHOCOLATE:--The proportions used for the best description are said to be--2 beans of vanilla, and 1 lb. of the best refined sugar, to every 3 lbs. of the choicest cacao nuts.
2. SPANISH CHOCOLATE:--The following forms are said to be commonly adopted:--
_a._ Caracas cocoa, 11 lbs.; sugar (white), 3 lbs.; vanilla, 1 oz.; cinnamon (cassia), 1/4 oz.; cloves, 1/2 dr.
_b._ Caracas cocoa, 10 lbs.; sweet almonds, 1 lb.; sugar, 3 lbs.; vanilla, 1-1/4 oz.
_c._ Caracas cocoa, 8 lbs.; island cocoa, 2 lbs.; white sugar, 10 lbs.; aromatics, as above.
_d._ Island cocoa, 7 lbs.; farina, q. s. to absorb the oil. Inferior.
3. VANILLA CHOCOLATE. _Syn._ CHOCOLAT À LA VANILLE, Fr. A variety of French or Spanish chocolate highly flavoured with vanilla. The following proportions have been recommended:--
_a._ Caracas cocoa, 7 lbs.; Mexican vanilla, 1 oz.; cinnamon, 1/2 oz.; cloves, 3 in no.
_b._ Best chocolate paste, 21 lbs.; vanilla, 4 oz.; cinnamon, 2 oz.; cloves, 1/2 dr.; musk, 10 gr.
_Obs._ The vanilla used in making chocolate is reduced to powder by rubbing it with a little sugar before adding it to the paste.
_Pur., &c._ The chocolate commonly sold in England is prepared from the cake left after the expression of the oil, and this is frequently mixed with the roasted seeds of ground peas, and maize or potato flour, to which a sufficient quantity of inferior brown sugar, or treacle and mutton suet, is added to make it adhere together. Inferior sweet almonds are also employed in the same way.
Since the above paragraph was written there has been a vast improvement in English chocolates, though the cheaper sorts of certain makers are still much adulterated. Genuine chocolate should dissolve in the mouth without grittiness, and should leave a peculiar sensation of freshness; after boiling it with water the emulsion should not form a jelly when cold, for if it does starch or flour is present. The presence of animal fat may generally be detected by a cheesy or rancid flavour. See COCOA.
_Qual., &c._ Chocolate is nutritive and wholesome if taken in moderation, but is sometimes apt to disagree with weak stomachs, especially those that are easily affected by oily substances or vegetable food. When this is the case, by adopting the simple plan recommended under BUTTER, chocolate may generally be taken with impunity, even by the dyspeptic. The quantity of aromatics mixed with the richer varieties of chocolate improve the flavour, but render them more stimulant and prone to produce nervous symptoms and head complaints.
Chocolate is taken in the solid form, or made into a beverage; or, combined with sugar, is made into various articles of confectionery.
CHOCOLATE FOR THE TABLE is prepared by slicing or scraping very finely the required quantity into a jug, and adding to it a small quantity of boiling water. This is worked into a thin, smooth paste, and the jug immediately filled up with boiling milk-and-water. A froth is produced by the same means that eggs are beaten up. The operation of "milling," performed by rapidly twirling a notched cylinder of wood in the emulsion, raises the froth very quickly. Sugar may be put in with the scraped chocolate, or added afterwards at pleasure.
Chocolate should never be made for the table before it is wanted, because beating it again injures the flavour, destroys the froth, and separates the body of the chocolate, the oil of the nut being observed, after a few minutes' boiling, or even standing long by the fire, to rise to the top. This is one of the principal reasons why chocolate offends the stomach.
Preparations of chocolate, intended either as nutritious articles of food for convalescents, or as vehicles for medicine, are common among the pharmacop[oe]ial and magistral formulæ of the Continent. The following are a few examples:--
=Chocolate, Aromat'ic.= _Prep._ (Weiglebt.) Cocoa beans and sugar, of each 16 oz.; cinnamon, 1/2 oz.; cloves, 2 dr.; cardamoms and vanilla, of each 1 dr.
=Chocolate, Car'rageen.= See CHOCOLATE, WHITE (Nos. 1 and 2).
=Chocolate, Chalyb'eate.= _Syn._ FERRUGIN'EOUS CHOCOLATE; CHOCOLA'TA CHALYBEA'TA, C. MAR'TIS, L. _Prep._ 1. (Trousseau.) Spanish chocolate, 16 oz.; carbonate of iron, 1/2 oz.; mix, and divide into 1-oz. cakes. One at a time; in anæmia, amenorrh[oe]a, chlorosis, &c.
2. (Pierquin.) Iodide of iron, 2 dr.; chocolate, 16 oz. For 1/2-oz. cakes; as above, and in scrofulous and glandular affections.
=Chocolate, Guarana'.= _Syn._ PAULLIN'IA CHOCOLATE; CHOCOLA'TA PAULIN'IÆ, C. GUARAN'Æ, L. _Prep._ From guarana and white sugar, of each 1 oz., triturated together, and afterwards thoroughly mixed with good plain chocolate, 18 oz. Recommended as a restorative in debility, chlorosis, and other diseases of debility, especially those of a nervous character.
=Chocolate, Ice'land Moss.= _Syn._ CHOCOLA'TA CETRAR'IÆ ISLAND'ICÆ, C. LICHEN'IS, L. _Prep._ 1. (P. C.) Simple chocolate (P. C.), 32 parts; sugar, 29 parts; dried jelly of Iceland moss, 11 parts; mix.
2. (Cadet.) Chocolate, 4 lbs.; sugar, 2 lbs.; Iceland moss (freed from its bitter, and powdered), 1-1/2 lb.; tragacanth and cinnamon, of each 4 oz.; water, q. s.; to be beaten in a warm mortar, or ground with a muller on a warm slab to a paste. Recommended in pulmonary affections, general debility, weakness of stomach, &c. See COCOA (Iceland Moss).
=Chocolate, Pur'gative.= _Syn._ CHOCOLA'TA PUR'GANS, C. CATHAR'TICA, L. _Prep._ 1. Jalap, 1 oz.; chocolate, 9 oz.; mix, and divide into 1-dr. cakes.--_Dose_, 1 to 2 cakes, as a purge.
2. Jalap, 2 oz.; calomel and sugar, of each 1 oz.; triturate together, then add chocolate, 20 oz.; for 1-dr. cakes.
3. Scammony, 2 dr.; chocolate, 3 oz.; for 1 dozen cakes. The last two are given in worms.--_Dose_ (for an adult), 1 cake, taken fasting.
=Chocolate, Sal'ep.= _Syn._ SAL'OOP CHOCOLATE; CHOCOLA'TA CUM SAL'EP, L. _Prep._ 1. (P. C.) Chocolate, 16 oz.; powdered salep, 1/2 oz.
2. (Cadet.) Cacao paste and sugar, of each 1 lb.; powdered salep, 1 oz. Arrowroot chocolate and tapioca chocolate are made in the same manner. (See _below_.)