In Sind large quantities of oil are prepared from the livers of different fish. The sharks (Carcharias melanopterus) are caught principally in October and November, for at that period the livers are much more developed than at any other season. The oil obtained from them is of the same quality whatever the season, but they furnish about three times the quantity in autumn that they do in any other season. The most esteemed livers are firm, and of a rose colour; those which are whitish and flabby are rejected as inferior. After having separated the vesicle, the livers are washed, and all the blood is taken out through incisions. They are then cut into medium-sized pieces, which are placed in a large earthen vessel with enough water to cover them. They are now heated for 15 or 20 minutes, after which they are allowed to cool. The oil, which soon floats to the surface, is gathered in ladles made from the half of a cocoa-nut, and is then poured into glazed earthenware jars. It is now passed through a sieve, and all which does not pass through is thrown away. Three or four days later, it is again filtered through a thick strainer, in order to separate the abundant deposit of stearine, and it is necessary to repeat this operation four times, at intervals of from 20 to 25 days, to separate the deposit; after which the oil remains clear, of a fine straw colour, and smelling very much like cod-liver oil. Thus prepared, it is reserved for medical purposes.

In India a manufacture of inferior oil is also carried on, which is used for lighting and other domestic purposes. It is prepared from the liver of sharks, rays, and other sorts of fish mixed. The livers are heated without being previously washed or picked, and the product is not purified.

From Bombay sharks' fins weighing 6000 to 9000 cwts. are exported annually, valued at from £14,000 to £20,000.

Besides the local catch, large quantities are imported from the Arabian and Persian Gulfs. There is a small export of these fins from Madras to the extent of 250 to 300 cwts. annually. They are assorted into the "white" and "black," the former being the dorsal fins, which are uniformly light coloured on both sides, and reputed to yield more gelatine than the other; the "black" are the pectoral, ventral, and anal fins, which are less esteemed than the white, and consequently realize a lower price.

Sharks' fins are sent to China from various quarters; from Akyab, Sumatra, Manila, Borneo, the Sandwich Islands, and other places. They are much esteemed as a food substance, being used for making soup.

CHAPTER VIII.

THE ISINGLASS OF COMMERCE.

Description and uses of isinglass-Fish from which obtained-Russian isinglass --Vesiga-Brazilian isinglass-West Indian isinglass-North American isinglass-Chinese isinglass-Fish maws and sharks' fins.

ISINGLASS, one of the purest and finest of the animal glues, is a product the preparation of which was long carried on almost exclusively in Russia, and chiefly obtained from the sturgeon. The value of the isinglass from this fish is chiefly due to its peculiar organic texture, on which the property of clarifying wines and beers depends. No artificial isinglass, however pure the gelatine, or identical as to chemical composition with the air-bladder of the sturgeon, answers the purpose of the preparers of fermented liquors.

Isinglass is brought to market in different forms; sometimes in that of plates or lumps, or in the form of a bag or purse, at other times rolled up in different shapes, which pass under the names of book, leaf, long and short staples, tongue or pipe, and it is cut into fine threads. When of good quality, isinglass is of a whitish colour, thin, and semitransparent, but tough and flexible, destitute of taste as well as of smell. The inferior kinds are thicker, yellowish coloured, opaque, and sometimes have a fishy smell and taste. When placed in cold water, it becomes soft, then

swells, and if held up to the light in this state is opalescent. In boiling water pure isinglass is entirely dissolved, with the exception of a very minute proportion of impurities. Though the best isinglass is thus completely dissolved in hot water, yet most of that met with in commerce does not become so, in consequence of the presence of albuminous parts.

The fine shreds into which it is cut and kept in shops. give great facility for making a jelly in the shortest possible time. This can be made palatable and nourishing by the addition of sugar and milk, acids or spices; about one-third or half an ounce is sufficient for a pint of water. It may also be taken in the form of a soup, with the addition of salt, spices, and sweet herbs, or it may be employed medicinally as a demulcent, either externally or internally. The best kinds of isinglass are alone employed in articles of diet and for the best confectionery, being added in small quantities to other, especially vegetable, jellies, to give them a tremulous appearance; but gelatine is now frequently substituted.

Isinglass appears to have been discovered many ages since, for certainly it was known to the Romans, being mentioned by Pliny. It is obtained in several parts of the world from the air-vessels (termed "sounds or maws") of various species of sea, estuary, and fresh-water fishes, England procures the best from Russia, where it is principally collected from the family Accipenserida or sturgeons, and the following species, according to Brandt and Ratzeburg, furnish it :-Accipenser sturio, the common sturgeon; A. huso, the great sturgeon; A. Guldenstadtii, the osseter; A. rathenus, the sterlet; A. stellatus, the sevruga or starred sturgeon, in which account are likewise included the A. brevirostris; A. schypa; A. Ratzeburgii;

A. Lichtensteinii; also A. maculosus, and A. oxyrhynchus from North America.

Isinglass has, in a measure, had its consumption checked by its high price, and substitutes are employed, such as gelatine (of which it is itself the purest form). It is of a highly nutritious and unirritating nature, admirably adapted for the sick room, and the preparation of some forms of confectionery and cookery, besides being employed both externally and internally in medicine, in the preparation of court plaster, in some arts and manufactures, but more extensively for clarifying or fining wines and beer. The brewer employs it as follows:-Some, having been finely divided, is dissolved in sour beer, to the consistence of a

thick mucilage, and a portion is added to the fluid which it is intended to clarify, and after a longer or shorter period, suspended substances subside. Some suppose that all floating particles become entangled in the isinglass, and, uniting with it, form an insoluble compound which becomes precipitated; others, that when dissolved in a fluid it lessens its affinity for the suspended particles, which, being thus set free, subside.

The finest description of isinglass is thin, tough but flexible, white, semi-transparent, and destitute of both taste or smell; it almost entirely dissolves in boiling water, and