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ANIMAL . FA T S Name of See also:Fat. Source. Yield per cent. See also:Iodine Value. See also:Principal Use. Drying Fats. See also:Ice See also:bear Ursus maritimus 147 See also:Pharmacy See also:Rattlesnake Crotalus durissus 106 Pharmacy Semi-drying Fats. Horses' fat. . ~ Equus cabatlus 75-85 See also:Food, See also:soap Non-drying Fats. See also:Goose fat . Anser cinereus . 70 Food, pomades See also:Lard See also:Sus scrofa 50-70 Food, soap, candles See also:Beef marrow See also:Bos See also:taurus 55 Pomades See also:Bone . . Bos, Ovis . 46-56 Soap, candles See also:Tallow, beef . Bos taurus 38-46 Food, soap, candles, See also:lubricants Tallow, mutton Ovis See also:aries 35-46 Food, soap, candles, lubricants See also:Butter . Bos taurus 26-38 Food in See also:hair or woollen bags and submitted to See also:hydraulic pressure, by which a further portion of oil or fat is obtained (cf. Pressing, below). In the See also:case of those animal fats which are intended for edible purposes, such as lard, See also:suet for See also:margarine, the greatest cleanliness must, of course, be observed, and the temperature must be kept as See also:low as possible in See also:order to obtain a perfectly sweet and pure material. Pressing.—The boiling out See also:process cannot be applied to small seeds, such as See also:linseed and See also:rape See also:seed. Whilst the See also:original method of obtaining seed See also:oils may perhaps have been the same which is still used in See also:India, viz. trituration of (rape) seeds in a See also:mortar so that the oil can exude, it may be safely assumed that the process of expressing has been applied in the first instance to the preparation of See also:olive oil.. The first woman who expressed See also:olives packed in a See also:sack by heaping stones on them may be considered as the forerunner of the inventors of all the presses that subsequently came into use. See also:Pliny describes in detail the apparatus and processes for obtaining olive oil in See also:vogue among his See also:Roman contemporaries, who used already a See also:simple See also:screw See also:press, a knowledge of which they had derived from the Greeks. In the See also:East, where See also:vegetable oils See also:form an important See also:article of food and serve also for other domestic purposes, various ingenious applications of See also:lever presses and See also:wedge presses, and even of combined lever and wedge presses, have been used from the remotest See also:time. At an See also:early See also:stage of See also:history the See also:Chinese employed the same See also:series of operations which are followed in the most advanced oil See also:mills of See also:modern time, viz. bruising and reducing the seeds to See also:meal under an edge-See also: Since then the hydraulic press has practically completely superseded all other appliances-used for expression, and in consequence of this See also:epoch-making invention, assisted as it was later on by the accumulator—invented by See also: A further quantity is obtained by expressing the seed meal at a somewhat elevated temperature, reached by warming the comminuted seeds or fruits either immediately after they leave the five-roller See also: At present See also:vertical presses are almost exclusively in vogue; the three See also:chief types of these have been already mentioned. Continuously working presses (See also:compression by a conical screw) have been patented, but hitherto they have not been found practicable. Of the vertical presses the Anglo-American type of press is most in use. It represents an open press fitted with a number (usually sixteen) of iron press plates, between which the cakes are inserted by See also:hand. A hydraulic See also:ram then forces the table carrying the cakes against a press-See also:head, and the exuding oil flows down the sides into a tank below. The " Marseilles press" is largely used in the south of France. There the meal is packed by hand in " scourtins," bags made of plaited coco-See also:nut leaves—replacing the woollen cloths used in England. The packing of the press requires more See also:manual labour than in the case of the Anglo-American press; moreover, the Marseilles press offers inconvenience in keeping the bags straight, and the pressure cannot he raised to the same height as in the more modern hydraulic presses. Oil obtained from heated meal is usually more highly coloured and harsher to the See also:taste than cold drawn oil, more of the extractive substances being dissolved and intermixed with the oil. Such oils are hardly suitable for edible purposes, and they are chiefly used for manufacturing processes. According to the care exercised by the manufacturer in the range of temperature to which the seed is heated, various grades of oils are obtained. In the case of those seeds which contain more than 4o% of oil, such as arachis nuts and See also:sesame seed, the first expression in pressbags leads to difficulty, as the meal causes " spueing," i.e. the meal exudes and escapes from the press. Hence, in modern installations, the first expression of those seeds is carried out in so-called cage (clodding) presses, consisting of hydraulic presses provided with circular boxes or cages, into which the meal is filled. These cages or boxes are either constructed of See also:metal staves held together by a number of steel rings, or consist of one cylinder having a large number of perforations. The presses having perforated cylinders, although presenting mechanically a more perfect arrangement, are not preferable to the press cages formed by staves, as the holes become easily clogged up by the meal, when the cylinder must be carefully cleaned out. Modern improvements, with a view to cheapening of cost, effect the transport of the cages from one press See also:battery to another on rails. In order to dispense even with the charging of the presses by hand, in some systems the cages are first charged in a preliminary press,from which they are transferred mechanically by a swinging arrangement into the final press. Whilst the meal is under pressure the oil See also:works its way to the edge of the cake, whence it exudes. For this See also:reason an oblong form is the most favourable one for the easy separation of the oil. The edges of the cakes invariably retain a considerable portion of oil; hence the soft edges are pared off, in the case of the oblong cake in a cake-paring machine, and the parings are returned to edge-runners, to be ground up and again pressed with fresh meal. Through the introduction of the cage (clodding) presses circular cakes have become fashionable, and as the material of these presses can be made much stronger and therefore higher pressure can be employed, more oil is expressed from the meal than in open presses. The oil flowing from the presses is caught in reservoirs placed under the level of the See also:floor, from which it is pumped into storage tanks for settling and clarifying. Extraction by Solvents.—The cakes obtained in the foregoing process still retain considerable proportions of oil, not less than 4 to 5 %usually, however, about to %. If it be desired to obtain larger quantities than are yielded by the above-described methods, processes having for their See also:object the extraction of the seeds by volatile solvents must be resorted to. Extraction by means or See also:carbon bisulphide was first introduced in 1843 by See also:Jesse See also:Fisher of See also:Birmingham. Thirteen years later E. Deiss of See also:Brunswick again patented the extraction by means of carbon bisulphide (Eng. Pat. No. 390, 1856), and added " See also:chloroform, See also:ether, essences, or benzine or benzole" to the See also:list of solvents. For several years afterwards the process made little advance, for the See also:colour of the oils produced was higher and the taste much sharper. The oil retained traces of See also:sulphur, which showed themselves disagreeably in the See also:smell of soaps made from it, and in the blackening of substances with which it was used. Of course, the meal See also:left by the process was so tainted with carbon bisuiphide that it was absolutely out of the question to use the extracted meal as See also:cattle food. With the improvement in the manufacture of carbon bisulphide, these drawbacks have been surmounted to a large extent, and the process of extracting with carbon bisuiphide has specially gained much See also:extension in the extraction of expressed olive See also:mare in the south of France, in See also:Italy and in See also:Spain. Yet even now traces of carbon bisulphide are retained by the extracted meal, so that it is impossible to feed cattle with it. Carbon bisuiphide is comparatively cheap, and it is heavier than water, hence there are certain advantages in storing so volatile and inflammable a liquid. But owing to the physiological effect carbon bisuiphide has on the workmen, coupled. with the chemical See also:action of impure carbon bisuiphide on iron which has frequently led to conflagrations, the employment of carbon bisulphide must remain restricted. In 1863 See also:Richardson, See also:Lundy and See also:Irvine secured a patent (Eng. Pat. No. 2315) for obtaining oil from crushed seeds, or from refuse cake, by the solvent action of volatile See also:hydrocarbons from " See also:petroleum, See also:earth oils, asphaltum oil, See also:coal oil or shale oil, such hydrocarbons being required to be volatile under 2120 F." Since that time the development of the petroleum industry in all parts of the See also:world and the large quantities of low boiling-point hydrocarbons—naphtha —obtained from the petroleum See also:fields, and also the improvements in the apparatus employed, have raised this See also:system of extraction to the See also:rank of a competing See also:practical method of oil production. Of the other proposed volatile solvents See also:ordinary ether has found no practical application, as it is far too volatile and hence far too dangerous. Carbon tetrachloride, chloroform, See also:acetone and See also:benzene are far too expensive. Carbon tetrachloride would be an ideal solvent, as it is non-inflammable and shares with carbon bisulphide the See also:advantage of being heavier than water. Efforts have been made during the last few years to introduce this solvent on a large See also:scale, but its high See also:price and its physiological effect on the workmen have hitherto militated against it. At the present time the choice lies practically only between the two solvents, carbon bisuiphide and See also:naphtha (petroleum ether). Naphtha is preferable for oil seeds, as it extracts neither resins nor gummy matters from the oil seeds, and takes up less colouring matter than carbon bisulphide. Yet even with naphtha traces of the solvents remain, so that the.tneal obtained cannot be used for cattle feeding, notwithstanding the many statements by interested parties to the contrary. It is true that on the See also:continent extracted meal, especially rape meal from See also:good See also:Indian seed and palm See also:kernel meal, are somewhat largely used as food for cattle in admixture with press cakes, but in England no extracted meal is used for feeding cattle, but finds its proper use in manuring the See also:land. The apparatus employed on a large scale depends on the temperature at which the extraction is carried out. In the See also:main two types of extracting apparatus are differentiated, viz. for extraction in the cold and for extraction in the hot. The seed is prepared in a similar manner as for pressing, except that it is not reduced to a See also:fine meal, so as not to impede the percolation of the solvent through the mass. In the case of cold extraction the seed is placed in a series of closed vessels, through which the solvent percolates by displacement, on the " See also:counter-current " system. A battery of vessels is so arranged that one See also:vessel can always be made the last of the series to See also:discharge finished meal and to be recharged with fresh meal, so that the process is practically a continuous one. The See also:solution of the extracted oil or fat is then transferred to a steam-heated still, where the solvent is driven off and recovered by condensing the vapours in a cooling coil, to be used again. The last remnant of volatile solvent in the oil is driven off by a current of open steam blown through the oil in the warm state. The extracting process in the hot is carried out in apparatus, the principle of which is exemplified by the well-known Soxhlet extractor. The comminuted seed is placed inside a vessel connected with an upright refrigerator on trays or baskets, and is surrounded there by the volatile solvent. On heating the solvent with steam through a coil or jacket, the vapours rise through and around the meal. They pass into the refrigerator, where they are condensed and fall back as a condensed liquid through the meal, percolating it as they pass downwards, and reaching to the bottom of the vessel as a more or less saturated solution of oil in the solvent. The solvent is again evaporated, leaving the oil at the bottom of the vessel until the extraction is deemed finished. The solution of fat is then run off into a still, as described already, and the last traces of solvent are driven out. The solvent is recovered and used again. With regard to the merits and demerits of the last two mentioned processes--expression and extraction—the See also:adoption of either will largely depend on See also:local conditions and the See also:objects for which the See also:pro-ducts are intended. Wherever the cake is the main product, expression will commend itself as the most advantageous process. Where, however, the fatty material forms the main product, as in the case of palm kernel oil, or sesame and coco-nut oils from damaged seeds (which would no longer yieid proper cattle food), the process of extraction will be preferred, especially when the price of oils is high. In some cases the See also:combination of the two processes commends itself, as in the case of the production of olive oil. The fruits are expressed, and after the edible qualities and best class of oils for technical purposes have been taken off by expression, the remaining pulp is extracted by means of solvents. This process is known under the name of mixed process (huilerie mixte). Refining and See also:Bleaching. The oils and fats prepared by any of the methods detailed above are in their fresh state, and, if got from perfectly fresh (" sweet ") material, practically neutral. If care be exercised in the process of rendering animal oils and fats or expressing oils in the cold, the products are, as a See also:rule, sufficiently pure to be delivered to the consumer, after a preliminary settling has allowed any mucilaginous matter, such as animal or vegetable See also:fibres or other impurities, and also traces of moisture, to See also:separate out. This spontaneous clarification was at one time the only method in vogue. This process is now shortened by filtering oils through See also:filter presses, or otherwise brightening them, e.g. by blowing with See also:air. In many cases these methods still suffice for the production of commercial oils and fats. In See also:special cases, such as the preparation of edible oils and fats, a further improvement in colour and greater purity is obtained by filtering the oils over See also:charcoal, or over natural absorbent earths, such as See also:fuller's earth. Where this process does not suffice, as in the case of coco-nut oil or palm kernel oil, a preliminary purification in a current of steam must be resorted to before the final purification, described above, is carried out. Oils intended for use on the table which See also:deposit " stearine " in See also:winter must be freed from such solid fats. This is done by allowing the oil to cool down to a low temperature and pressing it through cloths in a press, when a limpid oil exudes, which remains See also:proof against cold—" winter oil." Most olive oils are naturally non-congealing oils, whereas the Tunisian and Algerian olive oils deposit so much " stearine " that they must be " demargarina.ted." Similar methods are employed in the production of lard oil, edible cotton-seed oil, &c. For refining oils and fats intended for edible purposes only the foregoing methods, which may be summarized by the name of See also:physical methods, can be used; the only chemicals permissible are alkalis or alkaline earths to remove See also:free fatty acids present. Treatment with other chemicals renders the oils and fats unfit for See also:consumption. Therefore all bleaching and refining processes involving other means than those enumerated can only be used for technical oils and fats, such .as lubricating oils, burning oils, paint oils, soap-making oils, &c. Bleaching by the aid of chemicals requires See also:great circumspection. There is no universal method of oil-refining applicable to any and every oil or fat. Not only must each kind of oil or fat be considered as a special problem, but frequently even varieties of one and the same oil or fat are See also:apt to cause the same difficulties as would a new individual. In many cases the purification by means of sulphuric See also:acid, invented and patentedby See also: The number of chemicals which have been proposed from time to time for the purification of oils and fats is almost See also:legion, and so See also:long as the nature of oils and fats was little understood, a See also:secret See also:trade in oil-purifying chemicals flourished. With our present knowledge most of these chemicals may be removed into the limbo of useless things. The general methods of bleaching besides those mentioned already as physical methods, viz. filtration over charcoal or bleaching earth, are chiefly methods based on bleaching by means of See also:oxygen or by See also:chlorine. The methods of bleaching by oxygen include all those which aim at the bleaching by exposure to the air and to sunlight (as in the case of artists' linseed-oil), or where oxygen or See also:ozone is introduced in the form of See also:gas or is evolved by chemicals, as See also:manganese dioxide, See also:potassium bichromate or potassium permanganate and sulphuric acid. In the process of bleaching by means of chlorine either bleaching See also:powder or bichromates and hydrochloric acid are used. It must again be emphasized that no general rule can be laid down as to which process should be employed in each given case. There is still a wide See also: The saponification value (saponification number) denotes the number of milligrams which one gramme of an oil or fat requires for saponification, or, in other words, for the neutralization of the See also:total fatty acids contained in an oil or fat. We thus measure the See also:alkali absorption value of all fatty acids contained in an oil or fat. The saponification values of most oils and fats See also:lie in the neighbourhood of 195. But the oils belonging to the rape oil See also:group are characterized by considerably lower saponification values, viz. about 175 on See also:account of their containing notable quantities of erucic acid, CnH.t,O2. In the case of those oils which do not belong to the rape oils and yet show abnormally low saponification values, the suspicion is raised at once that a certain amount of See also:mineral oils (which do not absorb alkali and are therefore termed " unsaponifiable ") has been admixed fraudulently. Their amount can be determined in a direct manner by exhausting the saponified mass, after dilution with water, with ether, evaporating the latter and weighing the amount of mineral oil left behind. A few of the blubber oils, like See also:dolphin See also:jaw and See also:porpoise jaw oils (used for lubricating typewriting See also:machines), have exceedingly high saponification values owing to their containing volatile fatty acids with a small number of carbon atoms. Notable also are coco-nut and palm-nut oils, the saponification See also:numbers of which vary from 240 to 260, and especially butter-fat, which has a saponification value of about 227. These high saponification values are due to the presence of (glycerides of) volatile fatty acids, and are of extreme usefulness to the See also:analyst, especially in testing butter-fat for added margarine and other fats. These volatile acids are specially measured by the Reichert value (Reichert-Wollny value). To ascertain this value the volatile acids contained in 5 grammes of an oil or fat are distilled in a minutely prescribed manner, and the distilled-off acids are measured by titration with decinormal alkali. Whereas most of the oils and fats, viz. all those the saponification value of which lies at or below 195, contain practically no volatile acids,i.e. have extremely low Reichert-Wollny values, all those oils and fats haying saponification'values above 195 contain notable amounts of volatile fatty acids. Thus, the Reichert-Meissl value of butter-fat is 25-30, that of coco-nut oil 6-7, and of palm kernel oil about 5-6. This value is indispensable for judging the purity of a butter.
One of the most important values in oil testing is the iodine value. This indicates the percentage of iodine absorbed by an oil or fat when the latter is dissolved in chloroform or carbon tetrachloride, and treated with an accurately measured amount of free iodine supplied in the form of iodine chloride. By this means a measure is obtained of the unsaturated fatty acids contained in an oil or fat. On this value a scientific See also:classification of all oils and fats can be based, as is shown by the above-given list of oils and fats. The unsaturated fatty acids which occur chiefly in oils and fats are oleic acid, iodine value 90.07; erucic acid, iodine value 75.15; linolic acid, iodine value 181.42; linolenic acid, iodine value 274.1; and clupanodonic acid, iodine value 367.7. Oleic acid occurs in all non-drying oils and fats, and to some extent in the semi-drying oils and fats. Linolic acid is a characteristic constituent of all semi-drying, and to some extent of all drying oils. Linolenic acid characterizes all vegetable drying oils; similarly clupanodonic acid characterizes all marine animal oils.
If one individual oil or fat is given, the iodine value alone furnishes the readiest means of finding its place in the above system, and in many cases of identifying it. Even if a mixture of several oils . and, fats be present, the iodine value assists greatly in the See also:identification of the components of the mixture, and furnishes the most important See also: Thus it points the way to the application of a further method to resolve the isolated fatty acids of an oil or fat into saturated fatty acids, which do not absorb iodine, and into unsaturated fatty acids, which absorb iodine in various proportions as shown above. This separation is effected by converting the alkali soaps of the fatty acids into See also:lead soaps and treating the latter with ether, in which the lead salts of the saturated acids are insoluble, whereas the salts of the above-named unsaturated acids are soluble. The saturated fatty acids can then be further examined, and valuable See also:information is gained by the determination of the melting-points and by treatment with solvents. Thus some individual fatty acids, such as stearic acid and arachidic acid (which is characteristic of ground nut oil) can be identified. In the mixture of unsaturated fatty acids, by means of some more refined methods, clupanodonic acid, linolenic acid, linolic acid and oleic acid can be recognized. By combining the various methods which have been outlined here, and by the help of some further additional special methods, and by reasoning in a strictly logical manner, it is possible tc resolve a mixture of two oils and fats, and even of three and four, into their components and determine approximately their quantities. The methods sketched here do not yet exhaust the armoury of the See also:analytical chemist, but it can only be pointed out in passing that the detection of hydroxylated acids enables the analyst to ascertain the presence of See also:castor oil, just as the See also:isolation and determination of oxidized fatty acids enables him to differentiate blown oils from other oils. Tests such as the Maumene test, the elaldin test and others, which formerly were the only resource of the chemist, have been practically superseded by the foregoing methods. The viscosity test, although of considerable importance in the examination of lubricating oils, has been shown to have very little discriminative value as a general test. Commerce.—It may be safely said of the See also:United See also:Kingdom that it takes the foremost position in the world as regards the extent of the oil and fat industries. An estimate made by the writer (Cantor Lectures, " Oils and Fats, their Uses and Applications," Society of Arts, 1go4, p. 795), and based on the most. reliable information obtainable, led to the conclusion that the sums involved in the oil and fat trade exceeded £1,000,000 perweek; in 1907 they approximated 1,25o,000 per See also:week. The great centres of the seed-oil trade (linseed, cotton-seed, rape-seed, castor-seed) are See also:Hull, See also:London, See also:Liverpool, See also:Bristol, See also:Leith and See also:Glasgow. Linseed is imported principally from the East Indies, See also:Argentina, See also:Canada, See also:Russia and the United States; cotton-seed is chiefly supplied by See also:Egypt and East India; rape-seed and castor-seed chiefly by East India. The importation of See also:copra and palm kernels for the production of coco-nut oil and palm-nut oil is also considerable, but in these two cases Great See also:Britain does not take the first place. See also:Fish and blubber oils are principally produced in See also:Dundee, London and See also:Greenock. The manufacture of See also:cod-See also:liver oil for pharmaceutical purposes is naturally some-what limited, as See also:Norway, See also:Newfoundland, and latterly also See also:Japan, are more favourably situated as regards the See also:supply of fresh cod, but the technical liver oils (cod oil, See also:shark-liver oil) are produced in very large quantities in See also:Grimsby, Hull, See also:Aberdeen, and latterly also on the See also:west coasts of the United Kingdom. The production of edible fats (margarine, lard compounds, and vegetable butters) has taken See also:root in this country, and bids See also:fair to extend largely. With regard to edible oils, edible cotton-seed oil is the' only table oil produced in Great Britain. The United Kingdom is also one of the largest importers of fatty materials. Practically the whole trade in palm oil, which comes exclusively from West See also:Africa,• is confined to Liverpool, and the bulk of the tallow imported into Europe from See also:Australasia, South See also:America and the United States, is sold in the marts of London and Liverpool. Lard reaches Great Britain chiefly from the United States. Amongst the edible oils and fats which are largely imported, butter takes the first rank (to an amount of almost £25,000,000 per annum). This food-stuff reaches Great Britain not only from all butter-exporting countries of the continent of Europe, but in increasing quantities also from See also:Australia, Canada, See also:Argentine, See also:Siberia and the United States of America. Next in importance is margarine, the See also:British production of which does not suffice for the consumption, so that large quantities must be imported from Holland, edible olive oil from Italy, the south of France, Spain and the Mediterranean ports generally. Coco-nut oil and copra, both for edible and technical purposes, are largely shipped to Great Britain from the East Indies and See also:Ceylon, See also:Java and the West Indies. Of lesser importance are greases, which form the by-product of the large slaughter-houses in the United States and Argentina, and American (See also:Canadian) and See also:Japanese fish oils. On the continent of Europe the largest oil-trading centres are on the Mediterranean (Marseilles and Triest), which are geographically more favourably placed than England for the production of such edible oils (in addition to the home-grown olive oil) as arachis oil, sesame oil and coco-nut oil. Moreover, the native See also:population itself constitutes a large consumer of these oils. In the north of Europe, See also:Hamburg, See also:Rotterdam, See also:Antwerp and See also:Copenhagen are the largest centres of the oil and fat trade. Hamburg and its neighbourhood produces, curiously enough, at present the largest amount of palm-nut oil. The United States takes the foremost place in the world for the production of cotton-seed and See also:maize oils, lard, bone fat and fish oils. Canada is likely to outstrip the United States in the trade of fish and blubber oils, and in the near future Japan bids fair to become a very serious competitor in the supply of these oils. Vast stores of hard vegetable fats are still practically wasted in tropical countries, such as India, Indo-See also:China and the Sunda Islands, tropical South America, Africa and China. With the improvement in transport these will no doubt reach See also:European manufacturing centres in larger quantities than has been the case hitherto. WAXES The waxes consist chiefly of the fatty acid See also:esters of the higher monohydric See also:alcohols, with which are frequently associated free alcohols as also free fatty acids. In the following two tables the " acids " and " alcohols " hitherto identified in waxes are .enumerated in a classified order: — AcIns Boiling Point. Melting Point. I ° C. Characteristic of Pmm.ressure. ° C I. Acids of the Acetic series C„H2n02 C13H2602 .. .. 57 Gondang See also:wax Ficocerylic acid . Myristic acid . . C14H2802 IOC. 250`5 53'8 See also:Wool wax Palmitic acid . . C16H32Q2 too 271'5 62.62 Beeswax, See also:spermaceti Carnaiibic acid . C24H4802 .. 72.5 Carnauba wax, wool wax Pisangcerylic acid . . . C24H4802 • . .. 71 Pisang wax Cerotic acid . C26H52O2 .. • • 77.8 Beeswax, wool wax, See also:insect wax lVielissic acid . . C36H6602 .. .. 91 Beeswax Psyllostearylic acid . C36H6602 . . . • 94–95 Psylla wax II. Acids of the Acrylic or Oleic series CnH2, ..2 02 Physetoleic acid . C16H36O2 .. • • 30 Sperm oil Doeglic acid (?) C19H2602 .. . . Lanopalmic acid . Cocceric acid . . C31H6203 • • • • 92-93 See also:Cochineal wax I V. Dihydroxylated acids of the series C„H2n04 — C26H6604 .. .. 104–105 Wool wax Lanoceric acid ALCOHOLS Boiling Point. Melting point. mm ° C ° C. Characteristic of Pressure. L Alcohols of the Ethane series C„Hzn+20 C16H340 . .. • 78 Pisang wax Pisangceryl See also:alcohol Cetyl alcohol (Ethal) . C16H160 76o 344 5o Spermaceti Octodecyl alcohol . C,8H380 15 210'5 59 Carnaubyl alcohol . C241-150O .. .. 68-69 Wool wax Ceryl alcohol . C26H64O .. .. 79 Chinese wax, See also:opium wax, wool fat Myricyl (Melissyl) alcohol . C36H62O .. .. 85-88 Beeswax, Carnauba wax Psyllostearyl alcohol C22H68O .. .. 68–7o Psylla wax II. Alcohols of the Allylic series C„H2n0 C12H240 .. .. ' 102–104 Wool wax See also:Lanolin alcohol . . . Ficoceryl alcohol . . . IV. Alcohols of the Glycolic series CnH2n+202 C36H62O2 .. .. 101-104 Cochineal wax Cocceryl alcohol . . . . V. Alcohols of the Cholesterol series C26H440 .. • • 148'4-150.8 Wool wax Cholesterol . . Isocholesterol . C26H440 .. .. 137-138 Spermaceti consists practically of cetyl palmitate, Chinese wax of ceryl palmitate. The other waxes are of more complex See also:composition, especially so wool wax. The waxes can be classified similarly to the oils and fats as follows: I. Liquid waxes. II. Solid waxes. A. Vegetable waxes. B. Animal waxes. The table enumerates the most important waxes:—WAXES There are only two liquid waxes known, sperm oil and See also:arctic sperm oil (bottlenose-See also:whale oil), formerly always classed together with the animal oils. In their physical properties the natural waxes simulate the fatty oils and fats. They behave similarlyto solvents; and in their liquid See also:condition leave a grease spot on See also:paper. An important See also:property of waxes is that of easily forming emulsions with water, so that large quantities of water can be incorporated with them (lanolin). The liquid waxes occur in the blubber of the sperm whale, and in the head cavities of those whales which yield spermaceti; this latter is obtained by cooling the crude oil obtained from the head cavities. Vegetable waxes appear to be very widely distributed throughout the vegetable kingdom, and occur mostly as a very thin film covering leaves and also fruits. A few only are found in sufficiently large quantities to be of com- mercial importance. So far carnaiiba wax is practically the only vegetable wax which is of importance in the world's markets.. The animal waxes are widely distributed amongst the See also:insects, the most important being beeswax, which is collected in almost all parts of the world. An ex- ceptional position is occupied by wool wax, the main constituent of the natural wool fat which covers the hair of See also:sheep, and is obtained as a by-product in scour- See also:ing the raw wool. Wool fat is now being purified on a large scale and brought into commerce, under the name of lanolin, as an Name of Wax. Source. Iodine Principal Use. Value. Liquid Waxes. Sperm oil. Physeter macrocephalus . 81-90 Lubricant Arctic sperm oil (Bottlenose oil) Hyperoodon rostratus 67–82 Lubricant Vegetable Waxes— Solid Waxes. 13 Polishes. See also:Phonograph mass Carnauba wax . .. Corypha cerifera . Animal Waxes Ovis aries 102 Ointment Wool wax . . Beeswax See also:Apis mellifica . 8.11 Candles, polishes Spermaceti (Cetin) Physeter macrocephalus 0–4 Candles, See also:surgery Insect wax, Chinese wax . Coccus ceriferus . I 0–1.4 Candles, polishes, sizes ointment the beneficent properties of which were known to Dioscorides in the beginning of the present era. Its chemical composition is exceedingly complex, and specially remarkable on account of the considerable proportions of cholesterol and isocholesterol it contains. Commerce.—The sperm oils are generally sold in the same markets as the fish and blubber oils (see above). For beeswax London is one of the chief marts of the world. In See also:Yorkshire, the centre of the woollen industry, the largest amounts of wool-fat are produced, all attempts to recover the hitherto wasted material in Argentine and Australia having so far not been attended with any marked success. Spermaceti is a comparatively unimportant article of commerce; and of Chinese wax . small quantities only are imported, as the home consumption takes up the bulk of the wax for the manufacture of candles, polishes and sizes. 2. Essential or Ethereal Oils. The essential, ethereal, or " volatile " oils constitute a very extensive class of bodies, which possess, in a concentrated form, the odour characteristic of the See also:plants or vegetable substances from which they are obtained. The oils are usually contained in special cells, glands, cavities, or canals within the plants either as such or intermixed with resinous substances; in the latter case the mixtures form oleo-resins, balsams or resins according as the product is viscid, or solid and hard. A few do not exist ready formed in the plants, but result from chemical See also:change of inodorous substances; as for instance, See also:bitter almonds and essential oil of See also:mustard. The essential oils are for the most part insoluble or only very sparingly soluble in water, but in alcohol, ether, fatty oils and mineral oils they dissolve freely. They ignite with great ease, emitting a See also:smoke freely, owing to the large proportion of carbon they contain. Their chief physical distinction from the fatty oils is that they are as a rule not oleaginous to the See also:touch and leave no permanent grease spot. They have an aromatic smell and a hot burning taste, and can be distilled unchanged. The crude oils are at the ordinary temperature mostly liquid, some are solid substances, others, again, deposit on See also:standing a crystalline portion (" stearoptene " in contradistinction to the liquid portion (" elaeoptene "). The essential oils possess a high refractive power, and most of them rotate the See also:plane of the polarized See also:light. Even so nearly related oils as the oils of See also:turpentine, if obtained from different See also:sources, rotate the plane of the polarized light in opposite directions. In specific gravity the essential oils range from 0.850 to 1.142; the See also:majority are, however, specifically lighter than water. In their chemical constitution the essential oils present no relationship to the fats and oils. They represent a large number of classes of substances of which the most important are: (t) Hydrocarbons, such as pinene in oil of turpentine, camphene in citronella oil, limonene in See also:lemon and See also:orange-See also:peel oils, caryophyllene in clove oil and cumene in oil of See also:thyme; (2) See also:ketones, such as camphor from the camphor See also:tree, and irone which occurs in orris root; (3) phenols, such as See also:eugenol in clove oil, See also:thymol in thyme oil, saffrol in sassafras oil, anethol in See also:anise oil; (q.) See also:aldehydes, such as citral and citronellal, the most important constituents of lemon oil and lemon-grass oil, See also:benzaldehyde in the oil of bitter almonds, cinnamic aldehyde in See also:cassia oil, vanillin in See also:gum See also:benzoin and heliotropin in the spiraea oil, &c.; (5) alcohols and their esters, such as geraniol (rhodinol) in rose oil and See also:geranium oil, linalool, occurring in See also:bergamot and See also:lavender oils, and as the acetic ester in rose oil, terpineol in See also:cardamom oil, menthol in See also:peppermint oil, eucalyptol in See also:eucalyptus oil and borneol in See also:rosemary oil and See also:Borneo camphor; (6) acids and their anhydrides, such as cinnamic acid in See also:Peru See also:balsam and See also:coumarin in woodruff; and (7) nitrogenous compounds, such as mustard oil, indol in See also:jasmine oil and eathranilic methyl-ester in neroli and jasmine oils. - Preparation from Plants.—Before essential oils could be prepared synthetically they were obtained from plants by one of the following , methods : (r) See also:distillation, (2) expression, (3) extraction, (4) enfleurage, (5) maceration. The most important of these processes is the first, as it is applicable to a large number of substances of the widest range, such as oil of peppermint,and camphor. The process is based on the principle that whilst the odoriferous substances are insoluble in water, their vapour tension is reduced on being treated with steam so that they are carried over by a current of steam. The distillation is generally performed in a still with an inlet for steam and an outlet to carry the vapours laden with essential oils into a See also:condenser, where the water and oil vapours are condensed. On standing, the distillate separates into two layers, an aqueous and an oily layer, the oil floating on or sinking through the water according to its specificgravity. The process of expression is applicable to the obtaining of essential oils which are contained in the rind or skin of the fruits belonging to the citron See also:family, such as orange and lemon oils. The oranges, lemons, &c., are peeled, and the peel is pressed against a large number of fine needles, the exuding oil being absorbed by See also:sponges. It is intended to introduce machinery to replace manual labour. The process of extraction with volatile solvents is similar to that used in the extraction of oils and fats, but as only the most highly purified solvents can be used, this process has not yet gained commercial importance. The process of enfleurage is used in those cases where the odoriferous substance is present to a very small extent, and is so See also:tender and liable to deterioration that it cannot be separated by way of distillation. Thus in the case of neroli oil the petals of orange blossom are loosely spread on trays covered with purified lard or with fine olive oil. The fatty materials then take up and See also:fix the essential oil. This process is principally employed for preparing pomades and perfumed oils. Less tender plants can be treated by the analogous method of maceration, which consists in extracting the odoriferous substances by macerating the See also:flowers in hot oil or molten fat. The essential oil is then dissolved by the fatty substances. The essential oil itself can be recovered from the perfumed oils, prepared either by enfleurage or maceration, by agitating the perfumed fat in a shaking machine with pure concentrated alcohol. The essential oil passes into the alcoholic solution, which is used as such in See also:perfumery. Synthetic Preparation.—Since the See also:chemistry of the essential oils has been investigated in a systematic See also:fashion a large number of the chemical individuals mentioned above have been isolated from the oils and identified. This first step has led to the synthetical production of the most characteristic substances of essential oils in the laboratory, and the synthetical manufacture of essential oils bade fair to See also:rival in importance the production of See also:tar See also:colours from the hydrocarbons obtained on distilling coal. One of the earliest triumphs of synthetical chemistry in this direction was the production of terpineol, the artificial See also:lilac See also:scent, from oil of turpentine. At present it is almost a by-product in the manufacture of artificial camphor. This was followed by the production of heliotropin, coumarin and vanillin, and later on by the artificial preparation of ionone, the most characteristic constituent of the See also:violet scent. At present the manufacture of artificial camphor may be considered a solved problem, although it is doubtful whether such camphor will be able to compete in price with the natural product in the future. The aim of the chemist to produce essential oils on a manufacturing scale is naturally confined at present to the more expensive oils. For so long as the great bulk of oils is so cheaply produced in nature's laboratory, the natural products will hold their field 'for a long time to come. A pplications.—Essential oils have an extensive range of uses, of which the principal are their various applications in perfumery (q.v.). Next to that they play an important part in connexion with food. The value of flavouring herbs, condiments and spices is due in a large measure to the essential oils contained in them. The commercial value of See also:tea, See also:coffee, See also:wine and other beverages may be said to depend largely on the delicate aroma which they owe to the presence of See also:minute quantities of ethereal oils. Hence, essential oils are extensively used for the flavouring of See also:liqueurs, aerated beverages and other drinks. Nor is their employment less considerable in the manufacture of See also:confectionery and in the preparation of many dietetic articles. Most See also:fruit essences now employed in confectionery are artificially prepared oils, especially is this the case with cheap confectionery (jams, marmalades, &c.) in which the artificial fruit esters to a large extent replace the natural fruity flavour. Thus amyl acetate is used as an See also:imitation of the jargoneile-See also:pear flavour; amyl valerate replaces See also:apple flavour, and a mixture of See also:ethyl and propyl butyrates yields the so-called See also:pine-apple flavour. Formic ether gives a See also:peach-like odour, and is used for flavouring fictitious See also:rum. Many of the essential oils find extensive use in See also:medicine. In the arts, oil of turpentine is used on the largest scale in the manufacture of varnishes, and in smaller quantities for the production of terpineol and of'artificial camphor. Oil of See also:cloves is used in the silvering of See also:mirror glasses. Oils of lavender and of spike are used as vehicles for See also:painting, more especially for the painting of pottery and See also:glass. The examination of essential oils is by no means an easy task. Each oil requires almost a spacial method, but with the progress of chemistry the extensive adulteration that used to be practised with fatty oils has almost disappeared, as the presence of fatty oils is readily detected. Adulteration of expensive oil with cheaper oils is now more extensively practised, and such tests as the determination of the saponification value (see above) and of the See also:optical rotation, and in special cases the isolation and quantitative determination of characteristic substances, leads in very many cases to reliable results. The colour, the boiling-point, the specific gravity and solubility in alcohol serve as most valuable adjuncts in the examination with a view to form an estimate of the genuineness and value of a See also:sample. Quite apart from the genuineness of a sample, its special aroma constitutes the value of an oil, and in this respect the judging of the value of a given oil may, apart from the purity, be more readily solved by an experienced perfumer than by the chemist. Thus See also:roses of different origin or even of different years will yield rose oils of widely different value. The cultivation of plants for essential oils has become a large industry, and is especially practised as an industry in the south of France (See also:Grasse, See also:Nice, See also:Cannes). The rose oil industry, which had been for centuries located in the valleys of See also:Bulgaria, has now been taken up in See also:Germany (near See also:Leipzig), where roses are specially cultivated for the production of rose oil. India and China are also very large producers of essential oils. Owing to the See also:climate other countries are less favoured, although lavender and peppermint are largely cultivated at See also:Mitcham in See also:Surrey, in See also:Hertford-See also:shire and See also:Bedfordshire. Lavender and peppermint oils of See also:English origin rank as the best qualities. As an See also:illustration of the extent to which this part of the industry suffers from the climate, it may be stated that oil from lavender plants grown in England never produces more than 7 to to% linalool acetate, which gives the characteristic scent to lavender oil, whilst oil from lavender grown in the south of France frequently yields as much as 35 % of the ester. The proof that this is due mainly to See also:climatic influences is furnished by the fact that Mitcham lavender transplanted to France produces an oil which See also:year by year approximates more closely in respect of its contents of linalool acetate to the product of the See also:French plant. For the essential oils, see F. B. Power, Descriptive See also:Catalogue of Essential Oils; J. C. Sawer, Odorographia (London, 1892.and 1894); E. Gildemeister and F. See also:Hoffmann, See also:Die aetherischen Ole (See also:Berlin, 1899), trans. (1900) by E. Kremers under the See also:title Volatile Oils (See also:Milwaukee, See also:Wisconsin) ; F. W. Semmler, Die aetherischen Ole nach ihren chemischen Bestandteilen unter Beriicksichtigung der geschichtlichen Entwickelung (Leipzig) ; M. See also:Otto, L'Industrie See also:des parfums (See also:Paris, 1909) ; O. Aschan, Chemie der alicyklischen Verbindungen (Brunswick, 1905) ; F. R. Heussler (translated by See also:Pond), The Chemistry of the See also:Terpenes (London, 1904). (J. Additional information and CommentsThere are no comments yet for this article.
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