Rosin or Colophony, thus named after the ancient city of Colophonia, in Ionia, where it seems to have first formed an article of commerce, but perhaps best known as "fiddler's rosin," exhibits properties varying according to the different kinds of resins. It may be transparent, translucent, or opaque, in proportion to the degree in which the crystallised abietinic acid is transformed into its amorphous anhydride; and it may vary in colour from pale yellow, golden, amber, or reddishyellow to a deep dark-brown or almost black. Then, too, some rosins are soft and can be indented with a finger-nail, while others are so hard that they can only be scratched with iron. Hard rosin is almost odourless and tasteless, has a glassy surface, is very brittle, and can easily be pulverised. It has a sp. gr. of 1·04-1'11 at 60° Fahr., softens at about 160°, and melts between 212°-275° Fahr.; and as regards solubility, it closely resembles resin. It is used in making sealing-wax, varnish, and resinous soaps, for sizing paper and papiér-mâché, &c.; but one of its special uses is for making brewers' pitch for coating the insides of beer-casks, and for distilling resinous oils, when the pitch used by shoemakers, &c., is left as residuum.

As pure resin is unsuitable, owing to its brittleness, for cleaning and lining the insides of beer-casks, about 8-10 per cent of linseed-oil, cotton-oil, resin-oil, or paraffin has to be added to give elasticity, and this compound forms brewers' pitch. It is made simply by melting the rosin in an open vessel and adding the oil or paraffin, while keeping the whole well stirred to mix it thoroughly, and form a golden to dark-brown pitch, which neither froths when melted, nor becomes hard and brittle when cool, and which neither taints the smell or the taste of the beer (as is ascertained by tests for 3-4 days in pitched and unpitched bottles).

Resin-oils are oily fluids obtained by the dry distillation of rosin in cylindrical iron retorts with worm-condensers. When the rosin in the retort melts at about 285° Fahr., the lid is closed and the distillation begins. Up to about 520° acetised water and light resin-oil (pinolin) is given off, and the latter is mixed with sodium-lye to neutralise the acid, then washed with water and re-distilled, when it forms the refined pinolin known commercially as "spirit or essence of resin." From about 520°-550° a dark oil, of a brown colour and sharp, pungent odour is given off, which is also refined by mixing with sodium-lye and washed with water, then used for making waggon-grease and lime-soap. From about 550° clear, aromatic pale oil distils off, which gives the largest and best product, that can either be used as a crude lubricating oil, or else refined by a somewhat elaborate process (consisting of washing, steaming, neutralising, saponifying, re-washing, and oxidising, &c.) to produce a clear, pale yellowish-green, non-resinous, and almost odourless oil used for lubricating and medical purposes, making perfumery, printers' ink, linoleum, &c. From about 600° a blue oil is given off, which can be refined in a similar manner. At about 650° a green oil is obtainable, which can be used to make waggon-grease, and a dry coke-like residuum is left. But as this is useless, even for fuel, the distillation usually ceases on the blue oil stage being completed, and the remainder forms pitch, which is poured out into moulds and used for ships' caulking, brush- and shoe-making, &c. The yield of these products varies from 6 to 8 per cent light resin-oil, 4 to 5 per cent dark oil, 50 to 55 per cent pale oil, 15 to 20 per cent blue oil, and 6 to 7 per cent green oil, the rest being either coke-like residuum or loss in distillation (Schwackhöfer, op. cit., pp. 355-365). The dry pitch-coke can, however, be made into lamp-black, by burning it under a cotton awning, like a tent or an inverted wine-filler, hung over it; and as the smoke filters through this, the fine particles of soot are left adhering, and can afterwards be scraped off.

VI. NOTE ON GRAZING IN WOODLANDS, AND ON

LEAF-FODDER.

As was remarked in the concluding portion of the Introduction (see vol. i. p. 102), grazing may often prove worth attention in woods and plantations. Judging from the whole tenor of many of the old forest laws, there seems to be no doubt that grazing was habitual in the natural woods, and that rights of common in pasturage were frequent throughout the tracts afforested— e.g., such as the grazing-rights still extant in the New Forest. But now, from various causes, there is far less of woodland grazing than formerly, or than there might be if purely economic considerations were to obtain in place of special care being given to kinds of game requiring quiet and stillness in the woods.

Owing partly to the humidity of our island climate and the comparative mildness of the winter season, and partly to very heavy thinning being customary, there is usually a far stronger and more luxuriant growth of grass and weeds throughout our woodlands than is to be found in inland Continental countries. Here, in most coniferous woods over about twenty years old, and especially under Larch, there is usually an undergrowth of grass; and though this is rather aperient at first, and neither so solid nor so gratifying a food for cattle as good meadow-grass, yet it is of much larger bulk and greater value in feeding-capacity than the rough and scanty herbage furnished by land of similar quality forming rough pasturage outside the plantations. The pasturing of sheep and cattle does no real damage to plantations of that age; and the improvement in pasture which was found to take place in woodlands, as well as in adjoining pastures sheltered to the leeward, was one of the advantages claimed for extensive plantations of Larch by those who advocated this early in the last century (see vol. i. p. 30). And when any Conifer-crop is cleared for re-plantation, a very good class of grazing can be had for the three to four years during which it is customary to leave the land fallow, in order to allow the treestumps to dry, and thus obviate danger to the new crop from the Pine-weevil. The quality of the grazing in woodlands depends mainly, other things being equal, on the amount of light acting on the soil.

On the Castlerigg estate (Derwentwater, Cumberland) the largest of the Conifer plantations is a block of 200 acres (Coomb Wood), an outlying plantation formed in 1846-8, of Larch with slight admixture of Spruce in moist parts and Scots Pine in exposed places. Here the rate of growth ascertained from the stems showed that they have taken from 10 to 16 years to increase by the last inch of radius (or 64 inches in girth), representing a current increase of over 3 per cent on the trees now forming the crop. Methodical and carefully kept estate accounts show (1) that this plantation was made at a cost of about £2 an acre (there being then no necessity for expensive wire-netting against rabbits) on land the fee simple of which was not more than £1 an acre; and (2) that from a very

1 That, in any case, after three or four years the grass begins to fall off in quality is probably due to a reduction in the quantity of readily available supplies of potash and phosphoric acid, because good grass gives (according to Wolff) 7.2 per cent of ash, containing 1.3 per cent potash and 0.3 per cent phosphoric acid.

early age this wood, being periodically thinned in sections, has yielded thinnings almost regularly year by year. As for some years past these thinnings have really been of the nature of partial clearances of the maturing (and nearly mature) crop, which have thus already liquidated a portion of its capital value, the stock of 53- to 55-year-old timber is not so large per acre as it otherwise would have been; but, as the grazing (of good quality) in the now rather open wood is let along with other pasture land at about five shillings an acre, this of itself forms an improved income from what the land could possibly have yielded for pasturage in the condition it was in before planting. The well-kept estate accounts consequently prove that this compact block of plantation of about 200 acres has been a very profitable and beneficial investment to the landowner (Nisbet, article on Forestry, in the Victoria County History of Cumberland, vol. ii., 1905).

The general fodder-value of woodland grazing is reckoned at from about one-half to two-thirds of that of good meadow-grass; hence, if 3 per cent of the living weight of each beast be required for a good, satisfying feed of meadow-grass, from 4 to 6 lb. weight of woodland fodder will be required for each 100 lb. live weight of the beasts grazed. The number of cattle that can be grazed on every 10 acres of plantation must therefore depend on the given conditions, and no general average can be quoted.

On the Continent woodland grazing still forms an important branch of rural economy in many Alpine and other mountainous districts, although in general it has gradually sunk in national-economic importance during the last century. But even where grazing is no longer customary in the woods, the grass along green lanes, or in young plantations, or on recent falls, &c., is in many places cut once or twice each summer, and brings in a small but regular annual return. Or it is sometimes harvested by the landowner himself, for feeding red-deer during the severe time of winter.

In many parts of Southern Europe the foliage of woodland trees is stripped and used as fodder for sheep and goats, and sometimes even for cattle in dry years like 1893 and 1901. All kinds of foliage, except Pine and Larch, are thus employed; but Maple and Sycamore, Ash, Canadian Poplar, Lime, Elm, Sallow or Goat-willow, and Acacia give the best fodder. In 1893, and for some years following, experiments were made to ascertain the fodder-value of bruised and boiled sprays of Spruce, &c., and with results that were not unfavourable. The chemical composition of the foliage was found closely to resemble that of meadowhay as regards the quantity of protein and food-stuffs; but as to the actual nutrition-value only a few empirical results are known, complete investigations regarding the digestibility of foliage-fodder not having been carried out. Proposals have been repeatedly made, however, to make extensive fodder-plantations in the poorly wooded districts of Dalmatia and Hungary.

The foliage is either stripped by hand from the shoots in coppices or copse-underwoods, or the shoots are cut off and dried with the leaves attached by being tied loosely in bundles and, if possible, brought under roof for protection against rain, which makes it black and unfit for fodder. An acre of Oak coppice gives about 4 to 8 cwt. of leaves and twigs, 40 per cent of which can be used as fodder, with a feeding-value equivalent to that of about 1 to 3 cwt. of hay, and worth locally from 8s. to 16s. Such foliage-fodder is provided by pollarding, or by thinning out unnecessary shoots in the coppice. The leaves and twigs are richest in mineral substances, and most nutritious as fodder when cut immediately after they have flushed fully (Bühler, in Lorey's Handbuch, &c., 1903, vol. ii. p. 286).