The principal use of gelatine is in the manufacture of various alimentary substances. It has proved very useful for taking casts of delicate and intricate objects, without showing seams. Its use among dyers has already been noted. Recently a new demand has been created, by the discovery that gelatine, in presence of a salt of chromium, is rendered insoluble by the chemical action of light. The most important application of so-called chromatized gelatine hitherto has been in the heliatype process, which is virtually a new art of lithography. If paper coated with a solution of bichromate of potash and gelatine be exposed to the light, the gelatinous film becomes to all intents and purposes a lithographic stone, from which an indefiuite number of copies of pbotog,raphic negatives may be taken. The compound is also used in a new process for rendering woven fabrics waterproof; cotton and linen that have been soaked in a weak solution of gelatine (or glue) and bichromate of potash become waterproof on exposure to daylight, without being impervions to air.
Probably a larger quantity of bones is applied to the fertilization of the soil than is consumed in all the other ways together. They are applied raw, calcined, or dissolved in sulphuric acid. Since the growth of Australian meat-preserving companies, a plan has been tried far reducing tbe enormous bulk of banes, and their consequently heavy freight, between that country and this. The hones are crushed fine, and then moulded into cakes resembling flooring tiles, measuring about 6 in. square and 3 in. thick, and weighing about 6 lb. each. They are sufficiently adhesive to be handled freely, while they are rapidly dissalved by wate,r. A tan weight can be got into 29 cub. ft.
Tho price of bones varies between about 5/. and 8/. per ton, according to cleanness, size, and fatness. Bone-ash sells at 7L ta 8/. per ton.
The following are the latest procnrable statistics concerning the imports and exports of bones to and from the United Kingdom :— Exports.
The quantities of bones exported fram the T.Tnited Kingdom in 1877 to all countries were, for manufacturing purposes, 26 tons, value, 292/. ; and for manure anly, 226 tons, value, 1469/.
See Blocks, Buttons, Celluloid, Cements (Glue), Ivory, Manures, Pottery.
Whalebone, or Baleen. (FR., Baleine ; GER., Fischbeine.)—ln deference to popular miscanc,ep tion regarding this substance, attributable partly to its unscientific name, it has been judged advisable to introduce it here, despite the fact that it does not possess a single feature in common with bone. The method of growth of the whalebone is a modification of the system of the rabbit's tooth or the elephant's tusk ; it contains no bone whatever, hnt resomble's rather a number of hardened hairs, cemented together by a sort of gum, its chemical composition, according to Brande, being a basis of albumen hardened by a small proportion of phosphate of lime. It forms a substitute for teeth in certain species of whales, especially the Balcena mysticetus (Greenland whale), and B. australis (Southern whale). The very diminutive nature of the creatures au which these animals feed— scarcely larger than a common house-fly—renders teeth unnecessary, and requires a kind of sieve, in which the prey may become entangled and crushed, and thus the interior of a whale's mouth has the appearance of being furnished vvith a forest of bristles.
The baleen is a depending growth from the sides of the upper jaw, and consists of a number of flat plates, or "blades," as they are technically termed, separated by gum, and fringed with coarse hair to assist in securing the food. Tbe position of the baleen is shown in the accompanying illus trations. In Fig. 383, the mouth is represented open, as when the animal is feeding ; A is the crown-bone whence the baleen depends ; B the lower jaw ; C the baleen or whalebone. Fig. 384
indicates the mouth closed, and the blades of baleen packed away by the action of the lower jaw. The number of blades on each side is commonly about 300. They are longest in the middle, reaching a maximum of 15 ft., but generally not exceeding 12 or 13 ft. ; their breadth at the mot is about 10 or 12 in., and thickness, 0.4 to 0.5 in. A full-grown Greenland whale yields about a ton of the substance. Aa imported from the Greenland seas, which are its chief source, it is generally divided into bandy pieces of 10 or 12 blades each ; but sonaetlmes the sailors have bad time during the voyage to strip off each blade separately, and to divest it of its hairy fringes. Before cutting up the blades for use, they aro cleaned and softened, by boiling for about two hours in long coppers, and are then fixed, while still hot, in the large wooden vice of a carpenter's bench, in a convenient position for being planed or shaved into the required strips by means of the tool shown in Fig. 385. It consists of two handles A D, an iron plate C D, with a guide notch E, and a semicircular knife F, which is screwed firmly to each end of the iron plate, and adjusted with its cutting edge on a plane exactly so much lower than the bottom of the notch as will repre sent the desired thickness of the slice to be stripped off. The notch of the tool is applied at the end of the " blade " farthest from the operator, and is theu dmwn towards the person, so as to cut always in the direction of the fibres, and never across them. These slices are dried, and planed smooth on their other surfaces. Whalebone is polished in different ways. According to ono plan, it is first scraped with pieces of glass, or steel scrapers, then rubbed with emery paper, and finally with tripoli or rotten-stone on a woollen cloth ; or iu another way, it is rubbed with ground pumice, or wet felt, and finished with dry quick lime, spontaneously slaked and sifted.
It possesses the valuable qualities of elasticity, flexibility, lightness, and strength combined. Heated by steam or in a sand-bath, it softens, and may be bent or moulded into various shapes, which It will retain if cooled under compression. When boiled, it becomes harder and darker coloured. Unlike tortoiseshell, it cannot be soldered. Its industrial applications are multifarious and important. The fibres detached in slicing the blades are used as a substitute for bristles in common brushes, and instead of hair for stuffing mattresses. From the thick parts of the blades, are made knobs for walking-sticks, and snuff-boxes. It is also used in the framework of hats, and in making ladies' bonnets, and even artificial flowers have been naade from white whalebone, which will take many bright aud durable colours. Narrow strips, grooved or rnade into ribs by being drawn through an aperture in a steel plate, are used for covering pocket telescopes, &c., being Wound around the tube and tucked under the rings at the ends ; broad, flat slices of parti-coloured whalebone are sometimes similarly used, the light portions being dyed green, and the dark remaining unchanged. Solid pieces of mixed colours are occasionally made into walking-sticks, and plaited strips of black and white are often employed on whips. A considerable quantity is still consumed in the manufacture of ladies' stays, but not nearly so much as formerly, and probably the principal demand now is for malting the stretchers of umbrellas, &c.
The price of whalebone fluctuates exceedingly, and may be put roughly at 50/. to 150/. per ton. The imports of whalebone were, in :— The quantity for 1877 was contributed as follows :— The northern whale fisheries, 987 cwt.; United States, 380 cwt.; other countries, 602 cwt.
The exports of whalebone in 1877 were, to Germany, 251 cwt., value, 15,216/. ; France, 126 cwt. value, 4700/.; other countdes, 96 cwt., value, 456/.