162 THE FARMER AT HOME. 



various kinds ; but the principal division of fevers is into remitting 

 fevers, which subside or abate at intervals ; and continued or contin- 

 ual fevers, which neither remit nor intermit. 



FIBRIN. A peculiar organic compound, found both in vegeta- 

 bles and animals. It is a soft solid, of a greasy appearance, insoluble 

 in water, which softens in the air, becoming viscid, brown, and semi- 

 transparent. On hot coals it melts, throws out greasy drops, crackles, 

 and evolves the smoke and odor of roasting meat. It is procured, in 

 its most characteristic state, from animal matter. It exists in chyle ; 

 it enters into the composition of blood ; and it forms the chief part of 

 muscular flesh ; and hence it must be regarded as the most abundant 

 constituent of the soft solids of animals. 



FILAMENTS. Vegetable filaments form a substance of great 

 use in the arts and manufactures, furnishing thread, cloth, cordage, 

 and the like. For these purposes the filamentous parts of henip and 

 flax are employed among us. Different vegetables have been em- 

 ployed in different countries for the same uses. In some parts of 

 Sweden a strong cloth is said to have been prepared from the stalks 

 of hops. These have been tried elsewhere, but without success. 

 Vegetable filaments, and the thread or cloth prepared from them, dif- 

 fer remarkably from wool, hair, silk, and other animal productions, 

 particularly in their disposition to imbibe coloring matters ; sundry 

 liquors, which give a beautiful and durable dye to those of the animal, 

 giving no stain at all to those of the vegetable kingdom. 



FILTRATION. This is the act of clarifying impure water for 

 domestic purposes. Filters for doing it are of various construction ; 

 but they all act, somehow or other, as a sieve, or strainer, having 

 innumerable small passages through which the fluid can percolate 

 slowly ; but as the passages are not sufficiently large to allow the 

 particles of matter which are mixed with the fluid to escape, they are 

 detained by the instrument. In cities where the water of wells is 

 usually impregnated with the various substances with which the entire 

 earth is there saturated ; and, indeed, wherever the water furnished 

 is impure, artificial filters are of great importance in domestic economy. 

 Every family should be supplied with one. Rarely can spring water 

 be found so free from extraneous mixtures, as that which has thus 

 been artificially purified. 



All springs of water which we are accustomed to call pure, are 

 only rendered so by the effect of natural filtration ; for the rain falling 

 upon the surface of the earth, soaks first into the vegetable mould 

 with which the surface is almost everywhere covered ; in passing 

 through this, it takes up not only dirt or earthy particles, but the 

 remains of vegetable substances, which are in the progress toward 

 decomposition ; the water is thus rendered turbid arid unwholesome 

 for domestic purposes ; such is the state of the waters of most rivers 

 \vhich are not supplied by springs alone, but by brooks running on 



