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twg_000012579000
vacuum in the second vessel. The third vessel may also be heated by means of live steam. The vapours arising from the last vessel of the evaporating plant, or in the case of a "single effect" from the vessel, are conveyed into a condenser and condensed by injection water, which is drawn off by means of the pump employe...
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maintaining a vacuum of inches in the vessel. In the most recent designs of large evaporative installations, the vapours generated from the last vessel are drawn through a device consisting of a number of tubes enclosed in a casing, and the latent heat raises the temperature of the treated lyes proceeding through the t...
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thus be observed that the object of multiple effects is to utilise all the available heat in performing the greatest possible amount of work. Special devices are attached to the plant for automatically removing the condensed water from the steam chambers without the loss of useful heat, and as a precaution against spla...
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conveyance to the steam chamber, dash plates and "catch-alls" or "save-alls" of various designs are fitted on each vessel. In working the plant, the liquor in each vessel is kept at a fairly constant level by judicious feeding from one to the other; the first vessel is, of course, charged with treated lyes. As the liqu...
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Tw. ( B.) salt begins to deposit, and may be withdrawn into one of the many patented appliances, in which it is freed from glycerine, washed and dried ready for use at the soap pans. Difficulty is sometimes experienced with the tubes becoming choked with salt, thereby diminishing and retarding evaporation. It may be ne...
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with lyes or water, but with careful working the difficulty can be obviated by washing out with weak lyes after each batch of crude glycerine has been run away, or by increasing the circulation. It is claimed that by the use of the revolving heater designed by Lewkowitsch, the salting up of tubes is prevented. The salt...
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and removed, evaporation is continued until a sample taken from the last vessel has a density of Tw. (. B.) at F. (. C.). When this point is reached, the crude glycerine is ready to be withdrawn into a tank, and, after allowing the excess of salt to deposit, may be transferred to the storage tank. The colour of crude
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glycerine varies from light brown to dark brown, almost black, and depends largely on the materials used for soap-making. The organic matter present in good crude glycerine is small in amount, often less than per cent.; arsenic, sulphides and sulphites should be absent. Crude glycerine is refined in some cases by the p...
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more particularly in the refined glycerine trade. _Distillation._--Crude glycerine is distilled under vacuum with the aid of superheated steam. The still is heated directly with a coal or coke fire, and in this fire space is the superheater, which consists of a coil of pipes through which high pressure steam from the b...
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a temperature of F. ( C.). To prevent the deposition and burning of salt on the still-bottom during the distillation, a false bottom is supported about foot from the base of the still. With the same object in view, it has been suggested to rotate the contents with an agitator fixed in the still. Every care is taken tha...
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still does not become overheated; this precaution not only prevents loss of glycerine through carbonisation, but also obviates the production of tarry and other bodies which might affect the colour, taste, and odour of the distilled glycerine. The vacuum to be used will, of course, depend upon the heat of the fire and ...
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results are obtained with an inch vacuum. There are quite a large number of designs for still heads, and "catch-alls," having for their object the prevention of loss of glycerine. The distillate passes into a row of condensers, to each of which is attached a receptacle or receiver. It is needless to state that the cond...
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excess of theoretical requirements. The fractions are of varying strengths and quality; that portion, with a density less than Tw. (. B.), is returned to the treated-lyes tank. The other portion of the distillate is concentrated by means of a dry steam coil in a suitable vessel under a inch vacuum. When sufficiently co...
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necessary, by treating with per cent. animal charcoal and passing through a filter press, from which it issues as "dynamite glycerine". The residue in the still, consisting of - per cent. glycerine and varying proportions of various sodium salts--_e.g._ acetate, chloride, sulphate, and combinations with non-volatile or...
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separated, floats on the surface as the liquor is cooling, and may be removed by ladles, or the whole mixed with waste charcoal, and filtered. The filtrate is then evaporated, when the volatile organic acids are driven off; the concentrated liquor is finally mixed with crude glycerine which is ready for distillation, o...
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class of commercial glycerine, although of limited use in various other branches of industry, finds its chief outlet in the manufacture of explosives. Specifications are usually given in contracts drawn up between buyers and sellers, to which the product must conform. The chief stipulation for dynamite glycerine is its...
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a cold mixture of strong nitric and sulphuric acids, it is converted into nitro-glycerine, which separates as an oily layer on the surface of the acid. The more definite and rapid the separation, the more suitable is the glycerine for dynamite-making. Dynamite glycerine should be free from arsenic, lime, chlorides, and...
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more than . per cent., and a portion diluted and treated with nitrate of silver solution should give no turbidity or discoloration in ten minutes. The specific gravity should be . at C. ( F.) and the colour somewhat yellow. _Chemically pure glycerine_ or double distilled glycerine is produced by redistilling "once dist...
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all fractions which do not withstand the nitrate of silver test. The distillation is very carefully performed under strict supervision. The distillate is concentrated and after treatment with animal charcoal and filtration should conform to the requirements of the British Pharmacopoeia. These are specified as follows: ...
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tests for lead, copper, arsenium, iron, calcium, potassium, sodium, ammonium, chlorides, or sulphates. It should contain no sugars and leave no residue on burning. _Animal Charcoal for Decolorisation._--The application of animal charcoal for decolorising purposes dates back a century, and various are the views that hav...
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of the so-called carbon present, and no doubt this is an important factor, coupled with the porosity. Others consider that the nitrogen, which is present in all animal charcoal and extremely difficult to remove, is essential to the action. Animal charcoal should be freed from gypsum (sulphate of lime), lest in the burn...
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into the glycerine and contaminate it. The "char" should be well boiled with water, then carbonate of soda or caustic soda added in sufficient quantity to give an alkaline reaction, and again well boiled. The liquor is withdrawn and the charcoal washed until the washings are no longer alkaline. The charcoal is then sep...
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hydrochloric acid; opinions differ as to the amount of acid to be used. Some contend that phosphate of lime plays such an important part in decolorising that it should not be removed, but it has, however, been demonstrated that this substance after exposure to heat has very little decolorising power. Animal charcoal bo...
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mixture consisting of equal parts of commercial hydrochloric acid (free from arsenic) and water for twelve hours, then washed free from acid, dried, and burned in closed vessels gives a product possessed of great decolorising power for use with glycerines. A good animal charcoal will have a dull appearance, and be of a...
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fine grains and not in the form of a powder. The charcoal from the filter presses is washed free from glycerine (which is returned to the treated lyes), cleansed from foreign substances by the above treatment and revivified by carefully heating in closed vessels for twelve hours. _Glycerine obtained by other Methods of...
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the result of concentration of "sweet water" produced in the manufacture of stearine and by the autoclave process. It contains - per cent. glycerol, possesses a specific gravity of .-., and may be readily distinguished from the soap-crude glycerine by the absence of salt (sodium chloride). This glycerine is easily refi...
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acid saponification methods requires to be rendered alkaline by the addition of lime--the sludge is separated, and the liquor evaporated to crude. The concentration may be performed in two stages--first to a density of Tw. ( B.), when the calcium sulphate is allowed to deposit, and the separated liquor concentrated to ...
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upwards. _Yield of Glycerine from Fats and Oils._--The following represent practicable results which should be obtained from the various materials:-- Tallow per cent. of per cent. Glycerol. Cotton-seed oil " Cocoa-nut oil " Palm-kernel oil " Olive oil " Palm oil " Greases (Bone fats) - " The materials vary in glycerol ...
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this the case with tallows and greases. Every care should be taken that the raw materials are fresh and they should be carefully examined to ascertain if any decomposition has taken place in the glycerides--this would be denoted by the presence of an excess of free acidity, and the amount of glycerol obtainable from su...
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reduced. . ANALYSIS OF RAW MATERIALS, SOAP, AND GLYCERINE. _Fats and Oils--Alkalies and Alkali Salts--Essential Oils--Soap--Lyes--Crude Glycerine._ _Raw Materials._--Average figures have already been given in Chapters III. and VIII. for the more important physical and chemical characteristics of fats and oils, also of ...
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details, text-books dealing exhaustively with the respective subjects should be consulted. FATS AND OILS. It is very undesirable that any of these materials should be allowed to enter the soap pan without an analysis having first been made, as the oil may not only have become partially hydrolysed, involving a loss of g...
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liable to develop rancidity, but actual sophistication may have taken place. Thus a sample of tallow recently examined by the authors contained as much as per cent. of an unsaponifiable wax, which would have led to disaster in the soap pan, had the bulk been used without examination. After observing the appearance, col...
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characteristic feature, the following physical and chemical data should be determined. _Specific Gravity at C._ This may be taken by means of a Westphal balance, or by using a picnometer of either the ordinary gravity bottle shape, with perforated stopper, or the Sprengel U-tube. The picnometer should be calibrated wit...
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may be taken at an elevated temperature, preferably that of a boiling water bath. _Free acidity_ is estimated by weighing out from to grammes of the fat or oil, dissolving in neutral alcohol (purified methylated spirit) with gentle heat, and titrating with a standard aqueous or alcoholic solution of caustic soda or pot...
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the flask are well shaken after each addition of alkali, and the reaction is complete when the slight excess of alkali causes a permanent pink coloration with the indicator. The standard alkali may be N/, N/, or N/. It is usual to calculate the result in terms of oleic acid ( c.c. N/ alkali = . gramme oleic acid), and
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express in percentage on the fat or oil. _Example._--. grammes were taken, and required . c.c. of N/ KOH solution for neutralisation. . . ------------------ = . per cent. free fatty acids, . expressed as oleic acid. The free acidity is sometimes expressed as _acid value_, which is the amount of KOH in milligrammes nece...
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in gramme of fat or oil. In the above example:-- . . ---------- = . acid value. . The _saponification equivalent_ is determined by weighing - grammes of fat or oil into a wide-necked flask (about c.c. capacity), adding c.c. neutral alcohol, and warming under a reflux condenser on a steam or water-bath. When boiling, th...
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of an approximately semi-normal alcoholic potash solution carefully added from a burette, together with a few drops of phenol-phthalein solution, and the boiling under a reflux condenser continued, with frequent agitation, until saponification is complete (usually from - minutes) which is indicated by the absence of fa...
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The value of the approximately N/ alkali solution is ascertained by taking c.c. together with c.c. neutral alcohol in a similar flask, boiling for the same length of time as the fat, and titrating with N/ hydrochloric or sulphuric acid. The "saponification equivalent" is the amount of fat or oil in grammes saponified b...
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potash. _Example._--. grammes fat required . c.c. N/ acid to neutralise the unabsorbed alkali. Fifty c.c. approximately N/ alcoholic potash solution required . c.c. N/ acid.. . - . = . c.c. N/ KOH required by fat. . / . = . Saponification Equivalent. The result of this test is often expressed as the "Saponification Val...
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of milligrammes of KOH required for the saponification of gramme of fat. This may be found by dividing , by the saponification equivalent or by multiplying the number of c.c. of N/ alkali absorbed, by . and dividing by the quantity of fat taken. Thus, in the above example:-- . . / . = . Saponification Value. The _ester...
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_ether value_, or number of milligrammes of KOH required for the saponification of the neutral esters or glycerides in gramme of fat, is represented by the difference between the saponification and acid values. In the example given, the ester value would be . - . = .. _Unsaponifiable Matter._--The usual method adopted ...
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or oil with c.c. of approximately N/ alcoholic potash solution by boiling under a reflux condenser with frequent agitation for about hour. The solution is then evaporated to dryness in a porcelain basin over a steam or water-bath, and the resultant soap dissolved in about c.c. hot water. When sufficiently cool, the soa...
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c.c. of ether added, the whole well shaken, and allowed to rest. The ethereal layer is removed to another separator, more ether being added to the aqueous soap solution, and again separated. The two ethereal extracts are then washed with water to deprive them of any soap, separated, transferred to a flask, and the ethe...
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The residue, dried in the oven at C. until constant, is the "unsaponifiable matter," which is calculated to per cent. on the oil. In this method, it is very frequently most difficult to obtain a distinct separation of ether and aqueous soap solution--an intermediate layer of emulsion remaining even after prolonged stan...
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this, such as addition of alcohol (when petroleum ether is used), glycerine, more ether, water, or caustic potash solution, or by rotatory agitation. A better plan is to proceed as in the method above described as far as dissolving the resulting soap in c.c. water, and then boil for twenty or thirty minutes. Slightly c...
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acid ( to ), boil until the fatty acids are clear, wash with hot water free from mineral acid, and dry by filtering through a hot water funnel. Two grammes of the fatty acids are now dissolved in neutral alcohol saturated with some solvent, preferably a light fraction of benzoline, a quantity of the solvent added to ta...
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unsaponifiable matter, and the whole boiled under a reflux condenser. After cooling, the liquid is titrated with N/ aqueous KOH solution, using phenol-phthalein as indicator, this figure giving the amount of the total fatty acids present. The whole is then poured into a separating funnel, when separation immediately ta...
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water (about C.) followed by neutral alcohol (previously saturated with the solvent), and transferred to a tared flask, which is attached to a condenser, and the benzoline distilled off. The last traces of solvent remaining in the flask are removed by gently warming in the water-oven, and the flask cooled and weighed, ...
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of the Unsaponifiable Matter._--Unsaponifiable matter may consist of cholesterol, phytosterol, solid alcohols (cetyl and ceryl alcohols), or hydrocarbons (mineral oil). Cholesterol is frequently found in animal fats, and phytosterol is a very similar substance present in vegetable fats. Solid alcohols occur naturally i...
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the oil, are not natural constituents of animal or vegetable oils and fats. The presence of cholesterol and phytosterol may be detected by dissolving a small portion of the unsaponifiable matter in acetic anhydride, and adding a drop of the solution to one drop of per cent. sulphuric acid on a spot plate, when a charac...
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coloration is produced. It has been proposed to differentiate between cholesterol and phytosterol by their melting points, but it is more reliable to compare the crystalline forms, the former crystallising in lamin, while the latter forms groups of needle-shaped tufts. Another method is to convert the substance into ac...
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and phytosterol acetate at .- C. Additional tests for cholesterol have been recently proposed by Lifschtz (_Ber. Deut. Chem. Ges._, , -), and Golodetz (_Chem. Zeit._, , ). In that due to the former, which depends on the oxidation of cholesterol to oxycholesterol ester and oxycholesterol, a few milligrammes of the subst...
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a little benzoyl peroxide added, and the solution boiled, after which four drops of strong sulphuric acid are added, when a violet-blue or green colour is produced, if cholesterol is present, the violet colour being due to oxycholesterol ester, the green to oxycholesterol. Two tests are suggested by Golodetz () the add...
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consisting of five parts of concentrated sulphuric acid and three parts of formaldehyde solution, which colours cholesterol a blackish-brown, and () the addition of one drop of per cent. formaldehyde solution to a solution of the substance in trichloracetic acid, when with cholesterol an intense blue coloration is prod...
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a tared porcelain or platinum dish, and stirred with a thermometer, whilst being heated over a gas flame at C. until bubbling or cracking has ceased, and reweighed, the loss in weight representing the water. In cases of spurting a little added alcohol will carry the water off quietly. To prevent loss by spurting, Davis...
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) has suggested that the fat or oil should be added to a previously dried and tared coil of filter paper contained in a stoppered weighing bottle, which is then placed in the oven and dried at C. until constant in weight. Of course, this method is not applicable to oils or fats liable to oxidation on heating. _Dregs, D...
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Adipose Tissue, Fibre, etc._--From to grammes of the fat are dissolved in petroleum ether with frequent stirring, and passed through a tared filter paper. The residue retained by the filter paper is washed with petroleum ether until free from fat, dried in the water-oven at C. and weighed. If the amount of residue is l...
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the proportion and nature of the ash determined. The amount of impurities may also be estimated by Tate's method, which is performed by weighing grammes of fat into a separating funnel, dissolving in ether, and allowing the whole to stand to enable the water to deposit. After six hours' rest the water is withdrawn, the...
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dried, and the ethereal solution filtered through a dried tared filter paper into a tared flask. Well wash the filter with ether, and carefully dry at C. The ether in the flask is recovered, and the flask dried until all ether is expelled, and its weight is constant. The amount of fat in the flask gives the quantity of...
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fat in the sample taken; the loss represents the water and other impurities, and these latter may be obtained from the increase of weight of the filter paper. _Starch_ may be detected by the blue coloration it gives with iodine solution, and confirmed by microscopical examination, or it may be converted into glucose by...
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means of Fehling's solution. _Iodine Absorption._--This determination shows the amount of iodine absorbed by a fat or oil, and was devised by Hbl, the reagents required being as follows:-- () Solution of grammes iodine in c.c. absolute alcohol; () solution of grammes mercuric chloride in c.c. absolute alcohol, these tw...
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twelve hours before use; () a freshly prepared per cent. aqueous solution of potassium iodide; and () a N/ solution of sodium thiosulphate, standardised just prior to use by titrating a weighed quantity of resublimed iodine dissolved in potassium iodide solution. In the actual determination, . to . gramme of fat or fat...
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stoppered c.c. bottle, dissolved in c.c. chloroform, and c.c. of the Hbl reagent added, the stopper being then moistened with potassium iodide solution and placed firmly in the bottle, which is allowed to stand at rest in a dark place for four hours. A blank experiment is also performed, using the same quantities of ch...
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to stand for the same length of time. After the expiration of four hours c.c. of per cent. solution of potassium iodide and c.c. water are added to the contents of the bottle, and the excess of iodine titrated with N/ sodium thiosulphate solution, the whole being well agitated during the titration, which is finished wi...
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The blank experiment is titrated in the same manner, and from the amount of thiosulphate required in the blank experiment is deducted the number of c.c. required by the unabsorbed iodine in the other bottle; this figure multiplied by the iodine equivalent of c.c. of the thiosulphate solution and by , dividing the produ...
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gives the "Iodine Number". _Example._-- c.c. of the N/ sodium thiosulphate solution is found equal to . gramme iodine. . gramme of fat taken. Blank requires . c.c. thiosulphate. Bottle containing oil requires . c.c. thiosulphate. . - . = ., and the iodine absorption of the fat is-- . . ------------------ = .. . Wijs sh...
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employment of a solution of iodine monochloride in glacial acetic acid reliable iodine figures are obtained in a much shorter time, thirty minutes being sufficient, and this method is now in much more general use than the Hbl. Wijs' iodine reagent is made by dissolving grammes iodine in litre of glacial acetic acid and...
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the iodine is all converted into iodine monochloride. The process is carried out in exactly the same way as with the Hbl solution except that the fat is preferably dissolved in carbon tetrachloride instead of in chloroform. _Bromine absorption_ has now been almost entirely superseded by the iodine absorption, although ...
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(_Analyst_, , ) was employed by one of us for many years with very good results, whilst the bromine-thermal test of Hehner and Mitchell (_Analyst_, , ) gives rapid and satisfactory results. More recently MacIlhiney (_Jour. Amer. Chem. Soc._, , -) drew attention to bromine absorption methods and tried to rewaken interes...
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for discriminating between various oils and fats, and, in conjunction with other physical and chemical data, affords another means of detecting adulteration. Where a great number of samples have to be tested expeditiously, the Abb refractometer or the Zeiss butyro-refractometer may be recommended on account of the ease...
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C. The _Titre_ or setting point of the fatty acids was devised by Dalican, and is generally accepted in the commercial valuation of solid fats as a gauge of firmness, and in the case of tallow has a considerable bearing on the market value. One ounce of the fat is melted in a shallow porcelain dish, and c.c. of a
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per cent. caustic soda solution added, together with c.c. of redistilled methylated spirit. The whole is stirred down on the water bath until a pasty soap is obtained, when another c.c. of methylated spirit is added, which redissolves the soap, and the whole again stirred down to a solid soap. This is then dissolved in...
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of dilute sulphuric acid added to liberate the fatty acids, and the whole warmed until the fatty acids form a clear liquid on the surface. The water beneath the fatty acids is then syphoned off, more distilled water added to wash out any trace of mineral acid remaining, and again syphoned off, this process being repeat...
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no longer acid to litmus paper, when the fatty acids are poured on to a dry filter paper, which is inserted in a funnel resting on a beaker, and the latter placed on the water-bath, where it is left until the clear fatty acids have filtered through. About - grammes of the pure fatty acids are now transferred to a
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test tube, " ", warmed until molten, and the tube introduced through a hole in the cork into a flask or wide-mouthed bottle. A very accurate thermometer, graduated into fifths of a degree Centigrade (previously standardised), is immersed in the fatty acids, so that the bulb is as near the centre as possible, and when t...
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to solidify at the bottom of the tube, the thermometer is stirred round slowly. The mercury will descend, and stirring is continued until it ceases to fall further, at which point the thermometer is very carefully observed. It will be found that the temperature will rise rapidly and finally remain stationary for a shor...
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begin to drop until the temperature of the room is reached. The maximum point to which the temperature rises is known as the "titre" of the sample. ALKALIES AND ALKALI SALTS. Care should be bestowed upon the sampling of solid caustic soda or potash as the impurities during the solidification always accumulate in the ce...
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excess of that portion must be avoided or the sample will not be sufficiently representative. The sampling should be performed expeditiously to prevent carbonating, and portions placed in a stoppered bottle. The whole should be slightly broken in a mortar, and bright crystalline portions taken for analysis, using a sto...
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according to the alkali present in the form of caustic (hydrate) and carbonate. About grammes of the sample are dissolved in c.c. distilled water, and titrated with N/ sulphuric acid, using phenol-phthalein as indicator, the alkalinity so obtained representing all the caustic alkali and one-half the carbonate, which la...
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Na_{}O or . gramme NaOH and . gramme K_{}O, or . gramme KOH. After this first titration, the second half of the carbonate may be determined in one of two ways, either:-- () By adding from - c.c. of N/ acid, and well boiling for five minutes to expel carbonic-acid gas, after which the excess of acid is titrated with
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N/ soda solution; or () After adding two drops of methyl orange solution, N/ acid is run in until the solution acquires a faint pink tint. In the calculation of the caustic alkali, the number of c.c. of acid required in the second titration, divided by , is subtracted from that used in the first, and this difference mu...
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., or . gives the amount of Na_{}O or K_{}O respectively in the weight of sample taken, whence the percentage may be readily calculated. The proportion of carbonate is calculated by multiplying the amount of N/ acid required in the second titration by , and then by either . or . to give the amount of carbonate present,...
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twg_000012579083
Na_{}O or K_{}O respectively. An alternative method is to determine the alkalinity before and after the elimination of carbonate by chloride of barium. About - grammes of the sample are dissolved in water, and made up to c.c., and the total alkalinity determined by titrating c.c. with N/ acid, using methyl orange as in...
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chloride solution ( per cent.) until it ceases to give a precipitate, the precipitate allowed to settle, and the clear supernatant liquid decanted off, the precipitate transferred to a filter paper and well washed, and the filtrate titrated with N/ acid, using phenol-phthalein as indicator. The second titration gives t...
60
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two the proportion of carbonate. When methyl orange solution is used as indicator, titrations must be carried out cold. Reference has already been made (p. ) to the manner in which the alkali percentage is expressed in English degrees in the case of caustic soda. _Chlorides_ are estimated by titrating the neutral solut...
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being used as indicator. One c.c. N/ AgNO_{} solution = . gramme sodium chloride. The amount of acid necessary for exact neutralisation having already been ascertained, it is recommended to use the equivalent quantity of N/ nitric acid to produce the neutral solution. _Sulphides_ may be tested for, qualitatively, with ...
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manner; grammes are dissolved in water, rendered acid with HCl, excess of ammonia added, and the gelatinous precipitate of aluminium hydrate collected on a filter paper, washed, burnt, and weighed. * * * * * _Carbonated Alkali (Soda Ash)._--The total or available alkali is, of course, the chief factor to be ascertained...
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weigh out . grammes of the sample, dissolve in c.c. water, and titrate with N/ sulphuric or hydrochloric acid, using methyl orange as indicator. Each c.c. of N/ acid required represents per cent. Na_{}O in the sample under examination. A more complete analysis of soda ash would comprise:-- _Insoluble matter_, remaining...
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washed on to a filter-paper, dried, ignited, and weighed. The filtrate is made up to c.c., and in it may be determined:-- _Caustic soda_, by titrating with N/ acid the filtrate resulting from the treatment of c.c. (equal to gramme) with barium chloride solution. _Carbonate._--Titrate c.c. with N/ acid, and deduct the a...
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c.c. are exactly neutralised with nitric acid, titrated with N/ AgNO_{} solution, using potassium chromate as indicator. _Sulphates._--Twenty c.c. are acidulated with HCl, and the sulphates precipitated with barium chloride; the precipitate is collected on a filter paper, washed, dried, ignited, and weighed, the result...
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evolution of sulphuretted hydrogen and sulphurous acid respectively when the sample is acidulated. Sulphides may also be tested for, qualitatively, with lead acetate solution, or test-paper of sodium nitro-prusside. The total quantity of these compounds may be ascertained by acidulating with acetic acid, and titrating ...
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. gramme Na_{}SO_{}. The amount of sulphides may be estimated by titrating the hot soda solution, to which ammonia has been added, with an ammoniacal silver nitrate solution, c.c. of which corresponds to . gramme Na_{}S. As the titration proceeds, the precipitate is filtered off, and the addition of ammoniacal silver s...
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only a slight opacity. The presence of chloride, sulphate, hydrate, or carbonate does not interfere with the accuracy of this method. The ammoniacal silver nitrate solution is prepared by dissolving . grammes of pure silver in pure nitric acid, adding c.c. liquor ammoni fortis, and diluting to litre. _Carbonate of Pota...
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by taking . grammes of the sample, and titrating with N/ acid directly, or adding c.c. N/ sulphuric acid, boiling for a few minutes, and titrating the excess of acid with N/ caustic soda solution, using litmus as indicator. In this case each c.c. N/ acid required, is equivalent, in the absence of Na_{}CO_{}, to per cen...
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potash may be further examined for the following:-- _Moisture._--From - grammes are heated for thirty minutes in a crucible over a gas flame, and weighed when cold, the loss in weight representing the moisture. _Insoluble residue_, remaining after solution in water, filtering and well washing. _Potassium_ may be determ...
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quantity (say c.c.) of water, and carefully acidulate with hydrochloric acid, evaporate the resultant liquor to dryness in a tared platinum basin, and heat the residue gradually to dull redness. Cool in a desicator, weigh, and express the result as "mixed chlorides," _i.e._ chlorides of soda and potash. To the mixed ch...
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(the quantity may be three times the amount of the mixed chlorides) and evaporate nearly to dryness; add c.c. alcohol and allow to stand three hours covered with a watch-glass, giving the dish a gentle rotatory movement occasionally. The clear liquid is decanted through a tared filter, and the precipitate well washed w...
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the filter, dried and weighed. From the weight of potassium platino-chloride, K_{}PtCl_{}, is calculated the amount of potassium oxide K_{}O by the use of the factor /. or .. _Chlorides_, determined with N/ silver nitrate solution, and calculated to KCl. _Sulphates_, estimated as barium sulphate, and calculated to K_{}...
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potassium as determined above, from the total alkali. _Iron_, precipitated with excess of ammonia, filtered, ignited, and weighed as Fe_{}O_{}. SODIUM CHLORIDE (COMMON SALT). This should be examined for the following:-- _Actual Chloride_, either titrated with N/ silver nitrate solution, using neutral potassium chromate...
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