ORGANIC CHEMISTRY. 



OSIER. 



faction, to this last phenomenon several requi- 

 sites are necessary; moisture must be present, 

 and the temperature must not be below 32 of 

 Fahrenheit: in fact, it proceeds with extreme 

 slowness at a temperature below 46. It is re- 

 tarded in its progress by the absence of the 

 atmospheric air, but its presence is not essen- 

 tial : when water, however, is entirely absent, 

 putrefaction cannot proceed. 



The disagreeable odour which is emitted dur- 

 ing putrefaction is owing to the gaseous sub- 

 stances which are generated. Those plants 

 which contain nitrogen emit ammonia: onions 

 produce phosphuretted hydrogen. By all of 

 them carbonic acid gas and carburetted hydro- 

 gen gas are emitted in considerable quantities. 

 These gases, being, when presented to the roots 

 and leaves of plants, exceedingly invigorating, 

 are one of the causes of the increased luxuri- 

 ance of all crops manured with green vegeta- 

 ble matters. When the putrefaction of the 

 vegetable substance is at an end, the carbon, 

 hydrogen, and oxygen, of which it is composed, 

 are gone, and nothing remains but the earths 

 and salts with which the purely vegetable mat- 

 ters were once combined in the plant. The 

 ashes which are left when putrefaction ceases, 

 are in fact nearly the same as those left after 

 combustion. See PUTREFACTION. 



Animal substances. The analysis, of animal 

 substances is attended with all the difficulties 

 to which I have alluded as attendant upon the 

 examination of vegetable substances ; and the 

 progress of chemical philosophy has not yet 

 succeeded in demonstrating the composition of 

 any great proportion of the many substances 

 met with in the animal world. The great mass 

 of animal matters contain nitrogen, and this is 

 the chief general chemical difference between 

 animal and vegetable substances ; hence, when 

 animal substances putrefy, ammonia is disen- 

 gaged, for this alkali is composed of nitrogen 

 and hydrogen. 



The following analysis of several animal 

 matters will show how generally present is 

 nitrogen in this class of substances : 



These are the chief animal substances of 

 which most others are compounded. Thus 

 the principal solid matter of animal muscle is 

 fibrin. The outer skin or cuticle of animals is 

 composed of from 93 to 95 per cent, of albumen. 

 The solid matter of the blood is chiefly com- 

 posed of the same substance. Under the heads 

 A.MMAL MAXIIIKS, FISH, BOXES, GELATIN, &c., 

 the reader will find all the animal chemistry 

 bearing upon farming and rural affairs, with 

 which I am acquainted. The relative propor- 

 tions of the inorganic constituents of vegetable 

 substances forms a topic of great interest ; and 

 Professor G. F. W. Johnston's lectures upon the 

 subject, just published, will be read with satis- 

 866 



faction. See Lest IX., on the Application of Che* 

 niistry and Geologi. to .Agriculture. 



ORNITHOLOGY (Gr.). The science which 

 teaches the natural history and arrangement 

 of birds. 



OSIER. The name given to various species 

 of willow or salix, chiefly employed in basket- 

 making. Although under the heads SALLOW and 

 WILLOW are noticed most of the species of this 

 genus, it may be well to describe in this place, 

 a few of those which are more generally known 

 under the name osier. Osiers differ from sal- 

 lows in their long, straight, flexible, and mostly 

 tough twigs ; thin, generally sessile germens, 

 and elongated styles and stigmas. The osier 

 forms a hardy and useful hedge for excluding 

 boisterous winds ; and as it flourishes in wet 

 situations is frequently planted with a view to 

 prevent the banks of rivers being washed away 

 by the force of the current. Osiers are divided 

 into two classes : the first is known by their 

 blunt and downy or mealy leaves, which in the 

 other are more pointed, smooth, and green, re- 

 sembling the myrtle. 



The common osier (S.virninalis) is one of the 

 most abundant species. This tree is found 

 growing in wet meadows, osier-holts, the banks 

 of rivers, and other moist situations. The 

 branches are straight, erect, wand-like, very 

 long and slender, round, polished, downy when 

 young, with fine silky hairs. Leaves on short 

 foot-stalks, almost upright, about a span long, 

 and half an inch wide. The value of the com- 

 mon osier for various kinds of basket-work is 

 universally known. There is a variety much 

 esteemed, called the velvet osier, in which no 

 external difference is discernible, but the twigs 

 are said to be more pliant. There are also 

 various species as well as varieties compre- 

 hended under the name of osiers, some of 

 which, having smooth leaves, are noticed under 

 the articles SALLOW and WILLOW. 



The silky-leaved osier (S. Smithiana) is a 

 shrub found growing in meadows and osier 

 grounds, the branches of which are brittle and 

 unfit for basket-work. It is therefore important 

 for cultivators of osiers to distinguish carefully 

 between this and the velvet osier ; for while 

 the latter is, for some kinds of work, greatly 

 esteemed, the silky-leaved osier proves of no 

 utility. 



The auricled osier (S. stipularis') is a com- 

 mon species in osier-holts, hedges, and woods, 

 and is easily known at first sight by its coarse, 

 tall habit, and conspicuous stipules, but not 

 worthy of cultivation for any economical pur- 

 pose. The twigs are upright, tall, soft, and 

 downy, of a pale reddish-brown, brittle, and of 

 little or no use as an osier. 



The fine basket osier (S. Forbiana) is a shrub 

 grown in the meadows and osier-holts of the 

 eastern part of England. The stem is erect, 

 bushy, with upright, slender, smooth twigs, very 

 flexible and tough, of a grayish-yellow, not 

 purple hue, highly esteemed and much culti- 

 vated for the finer kinds of basket-work. 



Green-leaved osier (S. rubra). This is a 

 small tree, with long, upright, smooth, grayish 

 or purplish, more frequently tawny branches, 

 very tough and pliant, this being one of the 



