The scientific feeding of animals / by O. Kellner. Authorised translation of William Goodwin.

  • Kellner, O. (Oscar Johann), 1851-1911.
Date:
1915 [pref. 1908]
Catalogue details

Licence: In copyright

Credit: The scientific feeding of animals / by O. Kellner. Authorised translation of William Goodwin. Source: Wellcome Collection.

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    solid fat, similar to tallow, is the result. If, on the other hand, oleic acid is the chief acid present, then the fat at ordinary temperatures has a more or less fluid form, and is generally called an oil. In this book the word fat will be used to denote all sub¬ stances of this class, whether solid or liquid. Many oils, e.g. linseed, hemp, sunflower seed, take up oxygen when exposed to the air, and when spread in a thin layer become solid. They are called on this account drying oils. In most fats free fatty acids are found in addition to the compounds formed from fatty acids and glycerine. Fats freshly extracted from the animal body, or from new ripe seeds, contain only small amounts of these free fatty acids. Where, however, oily seeds are not fully ripe, or where, owing to bad weather at the time of harvesting, they have sprouted, large quantities of free fatty acids are to be found. When feeding-stuffs rich in fats are stored it is also found that the percentage of free fatty acids rises, particularly if there is much moisture present. Such food-stuffs soon acquire a sour taste and smell, and in time become quite rancid, owing to the further decomposition of the free fatty acids. In order to determine the quantity of fat in a feeding-stuff a finely ground sample is extracted with some solvent that will dissolve the fat. Ether is generally used for the extraction, and the residue left after distilling off the ether is dried and weighed.
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