The part played by fats and closely allied compounds in normal and abnormal metabolism need not here be discussed, as the subject is too complex and the views on it are conflicting.
These discoveries of Geoffroy and Scheele formed the basis of Chevreul's researches by which he established the constitution of oils and the true nature of soap. In the article Oils it is pointed out that all fatty oils and fats are mixtures of glycerides, that is, of bodies related to the alcohol glycerin C 3H5(OH)3 i and some fatty acid such as palmitic acid (C 16 H 31 0 2)H.
Of the natural fats or glycerides contained in oils the most important in addition to palmitin are stearin and olein, and these it may be sufficient to regard as the principal fatty bodies concerned in soapmaking.
Numerous varieties of soaps are made; the purposes to which they are applied are varied; the materials employed embrace a considerable range of oils, fats and other bodies; and the processes adopted undergo many modifications.
The most important of the animal fats are those of the ox and hog, and of the vegetable oils cotton-seed and coco-nut; it is also to be remembered that resin, although not a fat, is also important in soap-making.
The process of manufacturing soaps by boiling fatty acids with caustic alkalis or sodium carbonate came into practice with the development of the manufacture of candles by saponifying fats, for it provided a means whereby the oleic acid, which is valueless for candle making, could be worked up. The combination is effected in open vats heated by a steam coil and provided with a stirring appliance; if soda ash be used it is necessary to guard against boiling over.
Lewkowitsch, Oils, Fats and Waxes.
The neutral fats are composed of fatty acids and glycerin.
Hydrates, such as starches and sugars; fats; proteids, such as meat and eggs; salts; and last, but not least, water.
The fatty (fixed) oils and fats form a well-defined and homogeneous group of substances, passing through all gradations of consistency, from oils which are fluid even below the freezing-point of water, up to the hardest fats which melt at about 50° C. Therefore, no sharp distinction can be made between fatty oils and fats.
To this attitude he offered uncompromising opposition, and by the synthetical production of numerous hydrocarbons, natural fats, sugars and other bodies he proved that organic compounds can be formed by ordinary methods of chemical manipulation and obey the same laws as inorganic substances, thus exhibiting the "creative character in virtue of which chemistry actually realizes the abstract conceptions of its theories and classifications - a prerogative so far possessed neither by the natural nor by the historical sciences."
They are mainly carbohydrates such as starch and sugar, proteids in the form of globulins or albumoses, and in many cases fats and oils, while certain other bodies of similar nutritive value are less widely distributed.
It is obtainable from most natural fatty bodies by the action of alkalis and similar reagents, whereby the fats are decomposed, water being taken up, and glycerin being formed together with the alkaline salt of some particular acid (varying with the nature of the fat).
Berthelot, and many other chemists, from whose researches it results that glycerin is a trihydric alcohol indicated by the formula C 3 H 5 (OH) 3j the natural fats and oils, and the glycerides generally, being substances of the nature of compound esters formed from glycerin by the replacement of the hydrogen of the OH groups by the radicals of certain acids, called for that reason "fatty acids."
The chief constituent of hard animal fats, such as beef and mutton tallow, &c.; also contained in many vegetable fats in smaller quantity.
The simplest modes of preparing pure glycerin are based on the saponification of fats, either by alkalis or by superheated steam, and on the circumstance that, although glycerin cannot be distilled by itself under the ordinary pressure without decomposition, it can be readily volatilized in a current of superheated steam.
The processes and extent of the manufacture were revolutionized at about the beginning of the 19th century by Chevreul's classical investigations on the fats and oils, and by Leblanc's process for the manufacture of caustic soda from common salt.
Previous to Chevreul's researches on the fats (1811-1823) it was believed that soap consisted simply of a binary compound of fat and alkali.
Geoffroy in 1741 pointed out that the fat or oil recovered from a soap solution by neutralization with a mineral acid differs from the original fatty substance by dissolving readily in alcohol, which is not the case with ordinary fats and oils.
Organic acids also condense with alcohols to form similar compounds: the fats, waxes, and essential oils are naturally occurring substances of this class.
The imports consist principally of food stuffs, building materials, drinks, sugar, machinery, glass, fats, clothes, wooden and stone wares, and various manufactured goods.
Typical animals are holozoic, that is, they obtain their food by eating the tissues of other animals and plants: they take their food substances in the organized forms of proteids, fats and carbohydrates.
Fats doubtless originate by the " cleavage " of the synthetically formed proteids, or from carbohydrates.
It aids the absorption of fats and may be used with cod liver oil when the latter is administered by the skin.
V.) are undoubtedly the result of excessive ingestion of food material containing more neutral fats than the normal tissues can oxidize, or these, as a result of defective removal owing to enfeebled oxidative capacities on the part of the tissues, become stored up in the tissues.
In the physiological process of intestinal digestion, the precursors of such fats are split up into these two radicles.
By the reverse action on the part of the same ferments in the cell, these neutral fats may be redissolved and pass into the.lacteals.
The soluble soaps which are probably conveyed by the blood will be quickly taken up by such cells, synthetized into neutral fats, and stored in a non-diffusible form till required.
This splitting up of the fats previously combined with albumin in the cell by the action of natural ferments - lipases - and the setting free of the fats under the influence of toxins represent the normal and the pathological process in the production of so-called fatty degeneration.
The coloured fats, or lipochromes, are found normally in some of the cells of the internal organs, and under certain pathological conditions.
It is an excellent solvent for gums, resins, fats, &c.; sulphur, phosphorus and iodine also dissolve in it.
Olive oil), the soft fats which may be fluid in their country of origin (e.g.
Coco-nut oil, palm oil), the hard fats (e.g.
Fixed Oils, Fats and Waxes.
Fatty (fixed) oils and fats on the one hand, and waxes on the other, the distinction between the two classes being based on a most important chemical difference.
The fixed oils and fats consist essentially of glycerides, i.e.
The true chemical constitution of oils and fats was first expounded by the classical researches of Chevreul, embodied in his work, Recherches sur les corps Bras d'origine animale (1823, reprinted 1889).
The natural oils and fats are mixtures of at least two or three different triglycerides, the most important of which are tristearin, tripalmitin, C3H5(0'C16H310)3 and triolein, C 3 H 5 (0C1811330)3.
These three glycerides have been usually considered the chief constituents of most oils and fats, but latterly there have been recognized as widely distributed trilinolin, the glyceride of linolic acid, and trilinolenin, the glyceride of linolenic acid.
These glycerides are, therefore, characteristic of the oils and fats named.
Oils and fats must, therefore, not be looked upon as definite chemical individuals, but as representatives of natural species which vary, although within certain narrow limits, according to the climate and soil in which the plants which produce them are grown, or, in the case of animal fats, according to the climate, the race, the age of the animal, and especially the food, and also the idiosyncrasy of the individual animal.
The oils and fats are distributed throughout the animal and vegetable kingdom from the lowest organism up to the most highly organized forms of animal and vegetable life, and are found in almost all tissues and organs.