Cooley's Cyclopaedia of Practical Receipts Volume Ii Part 110

=OYS'TER.= _Syn._ OSTREA, L. This well-known sh.e.l.l-fish is the _Ostrea edulis_ (Linn.)

"The oyster is a genus of lamellibranchiate molluscs of the section with a single adductor muscle. The sh.e.l.l consists of two unequal and somewhat irregularly-shaped valves of laminated and closely foliated structure, and the hinge is without tooth or ridge, the valves being held together by a ligament lodged in a little cavity in each. The animal is in its organisation among the lowest and simplest of lamellibranchiate molluscs.

It has no foot, and, except when very young, no power of locomotion, or organ of any kind adapted to that purpose. Its food consists of animalcules, and also of minute vegetable particles, brought to it by the water, a continual current of which is directed towards the mouth by the action of the gills. The gills are seen in four rows when the valves of the sh.e.l.l are separated, a little within the fringed edge of the mantle.

In the most central part is the adductor muscle; and between the adductor muscle and the liver is the heart, which may be recognised by the brown colour of its auricle. The mouth--for, as in the other lamellibranchiata, there is no head--is situated beneath a kind of hood formed by the union of the two edges of the mantle near the hinge. It is jawless and toothless. The ovaries are very large during the season of reproduction, which extends over certain months when oysters are out of season for the table. Oysters are hermaphrodite."[82]

[Footnote 82: Chambers' 'Encyclopaedia.']

The fecundity of the oyster is amazing. Leeuwenhoek estimated that an oyster, when full of sp.a.w.n, contained from 3000 to 4000 of its offspring, and it has also been computed that one oyster alone produces nearly a million and a quarter of eggs. The eggs are hatched and the young produced within the sh.e.l.l and mantle of the parent, where they continue floating or swimming about in the vicinity of the gills in a creamy-looking kind of mucus or fluid until expelled. Their expulsion is preceded by a change of appearance in the fluid to a brownish or muddy colour; a circ.u.mstance that may possibly indicate an alteration of composition in the liquid unfavorable to the infant oyster, and thus lead to its departure. Their departure or expulsion from all the parent molluscs of the oyster-bank or bed takes place at the same time.

When they leave the parent sh.e.l.l the young oysters, which in this condition are called _spat_, are not more than 1/120th of an inch in length; and two millions of them when closely packed do not occupy a s.p.a.ce of more than a cubic inch. Thus cast adrift they are carried away by currents, their mult.i.tudinous numbers being considerably diminished by their falling a prey to numerous fish, as well as from their frequent inability to find a suitable resting-place. This obtained, the young oyster or spat attaches itself to it, and makes it the permanent home on which it eats, grows, and breeds, and, debarred of locomotion, pa.s.ses its existence unless, of course, removed by external causes. Pending its obtaining a suitable locality the young oyster is provided with a powerful swimming apparatus which, it has been surmised, becomes absorbed or otherwise disappears when its function is rendered unnecessary by the stationary life of the oyster after it has secured a habitat.

The objects to which it attaches itself are numerous. The _Ostrea parasitica_, a species of oyster found in warm climates, fixes itself to the roots and branches of trees growing within reach of and washed by the tide. Again, in some of the southern states of North America, large oyster-beds, which are sometimes of such magnitude as to form b.u.t.tresses against the force of the tides and winds, originate from the habit of young oysters attaching themselves to the sh.e.l.ls of old ones. Similarly the banks of some of the rivers of Georgia, which run up some few miles inland from the sea, are composed of ma.s.ses of living oysters attached to each other. These banks, which are so ma.s.sive as to make a channel for the river, are known as _rac.o.o.n banks_, because this animal is one amongst others which frequents them for the sake of devouring the oysters.... In some of the French _parcs_, or artificial oyster-beds, the young oysters attach themselves to large unglazed tiles, or to f.a.ggots or other solid bodies which are placed in suitable situations for the purpose; in the English artificial beds hurdles are frequently employed, upon which the spat become deposited. It appears the young oysters select dark objects, such as slate or black stones, in preference to bodies of a lighter colour to fix themselves to, and that they choose, where practicable, the inner side of the object, or that portion of it away from the light. After a time the young oysters are removed from the breeding beds, placed in the fattening beds, from whence they are removed when they have attained a sufficient size, and sent upon the market. In England oysters are not regarded as fit to be eaten until they are at least three years old; whereas in France they are served up to table about a year earlier. The chief enemy of the young oyster is a species of whelk, known in France as the _bigourneau_, _dog whelk_, or _piercer_. These creatures, which are found in immense quant.i.ties in the celebrated oyster-beds at Arcachon, near Bordeaux, cause great destruction amongst the bivalves. Part of their anatomy consists of a boring apparatus, with which they pierce the sh.e.l.l of the oyster; whatever of the dead oyster is left by the whelk is devoured by the crabs, which creep into the aperture in the sh.e.l.l made by the former.

We have already alluded to the abundance of oysters in parts of Georgia, where, we may add, they are not only confined to the alluvial sh.o.r.es of the rivers, but are also found in large numbers amongst the long gra.s.s of the adjoining low lands.

In these districts it is by no means an uncommon practice for the inhabitants to improvise a meal by picking up a bunch of oysters and roasting them over a fire kindled on the spot. In many of these localities the oysters occur in quant.i.ties so immense that a vessel of 100 tons might be loaded within three times her own length.[83]

[Footnote 83: Chambers' 'Encyclopaedia.']

There are also many other parts of America in which the yield of the oyster-beds is enormous. In the State of Maryland 6000 persons are said to be employed dredging, and nearly 11,000,000 bushels of oysters were taken in 1870-71.

In Baltimore as many as 10,000 persons are employed in tinning this bivalve. Comparing the plenteousness of the oyster in America with its great scarcity of late years in our country, and the consequent much lower price of the foreign bivalve, we should be prepared to learn that considerable supplies of oysters, both alive and preserved in tins, come to us from America. The bulk of those consumed in Britain are a small variety, and come from Maryland and Virginia.

In 1872, owing to the diminished yield of the English oyster-beds, an attempt was made to introduce the American oyster into British waters; and we believe the depot for this purpose still exists at Cleesethorpes, at the mouth of the Humber, where operations in this branch of oyster culture are being carried on by the Conway Company. If, however, the opinion of an eminent pisciculturist be correct, viz. that the American oyster will not breed in our waters, we should conceive the experiment will be abandoned, since nothing will be gained by relaying them, that cannot be attained by simply importing them and sending them to the market, since it is a.s.serted they are kept alive out of water for a month.

A few years back a Select Committee appointed by Parliament to inquire into the causes of the scarcity of oysters issued in 1876 a report in which, endorsing the opinion of previous authorities on oyster culture, they attributed the diminished yield of our oyster-beds to continual over-dredging for them in open waters, without allowing sufficient 'close time.' The Committee found that, in France, where the stringent observances of the 'close season' was enforced, the supply of oysters had increased concurrently. The Committee, therefore, recommended the establishment 'of a general close time,' extending from May 1st to September 1st, subject to certain exceptions under the supervision of the Board of Trade; the levying of penalties for buying or selling oysters for consumption during the 'close season' being also recommended. The Committee further recommended that no oysters should be sold from the deep-sea fisheries under 2-1/2 or 3 inches in diameter. Commenting upon the above report, 'Nature' very sensibly remarks:--"What is really wanted for the protection of the oyster is the a.s.surance that these animals shall not be sold before they have a chance of reproducing their kind. Since the introduction of the railway system, the demand for oysters in distant places has become so great and the price has risen so high, that oyster culturists are tempted to send immature animals to market, and it is this fact, more than any failure of spat, that is leading to the scarcity.

There are not, in consequence of the unceasing demand and consequent high price, so many full-grown oysters left to spat as there ought to be; hence the scarcity. Any Act of Parliament that decrees two oysters to grow where only one grew before will be greedily welcomed both by oyster culturists and by the public, and we hope that the issue of the present Report will lead to some effective measures being taken for the preservation of this delicious creature ere it be too late." Previous to 1846 the wholesale price of best English natives was 2 2s. a bushel; since then the price has risen rapidly to 4 4s. in 1865, in 1866 to 5, and in 1869 it had advanced to 8; that is, they had risen nearly 300 per cent. in 8 years, which is equivalent to an advance of from 1/2d. to 2d. each. At the present time they are, we believe, sold at from 3s. to 3s. 6d. a dozen by the retail dealer.

Oysters are nutritious and easy of digestion when fresh, but are apt to prove laxative to those unaccustomed to their use. It is generally believed that they are in season each month of the year the name of which contains the letter R. Whitstable in Kent, and Colchester and other places in Ess.e.x, are the great nurseries or feeding-grounds for supplying the metropolis, and, indeed, the whole of England, with the most esteemed variety (NATIVES) of this sh.e.l.l-fish. The sh.e.l.ls (TESTae PREPARATae, T.

OSTREARIae) were formerly used in medicine as an absorbent.

Of the various species of oysters, that which holds the foremost place in the estimation of the _gourmet_ is the 'English native,' now, alas! owing to the unwise rapacity of the collector, nearly dredged out of existence.

The native has a historic reputation too, since it appears it was eagerly sought after by the old Romans, and was a frequent dish at their tables.

The enthusiasm of the celebrated Dr Kitchener for this particular oyster was very intense. He is very particular in directing its sh.e.l.l to be opened with the greatest care so that it may be eaten alive and "_tickled to death by the teeth_."

The green oyster of Ostend is also prized by epicures; it acquires its colour from its food, which consists chiefly of green monads and confervaae. Some of the American oysters are excellent in flavour, and are said to be without the copper taste occasionally to be met with in English oysters. They smack a little of the mussel.

Payen gives the following as the composition of the oyster:--

Mean of two a.n.a.lyses.

Nitrogenous matter 14010 Fatty matter 1515 Saline matter 2695 Non-nitrogenous matter and loss 1395 Water 80385 ------ 10000

See Sh.e.l.l FISH, SAUCES, &c.

=Oyster, Scalloped.= Put them with crums of bread, pepper, salt, nutmeg, and a bit of b.u.t.ter, into scallop sh.e.l.ls or saucers, and bake them before the fire in a Dutch oven.

=Oysters, Fried= (to garnish boiled fish). Make a batter of flour, milk and eggs, add a little seasoning to it; dip the oysters into it, and fry them a fine yellow brown. A little nutmeg should be put into the seasoning, and a few crumbs of bread into the flour.

=Oysters, Stewed.= Open them, and separate the liquor from them, then free them from grit by was.h.i.+ng, strain the liquor, and add it to the oysters with a small piece of mace and lemon peel, and a few white peppercorns.

Simmer very gently, and add some cream and a little flour and b.u.t.ter. Let them be served with sippets.

=Oysters, To Feed.= Pat them into water, and wash them with a birch broom till quite clean. Then place them bottom downwards in an earthenware pan; sprinkle them with flour, oatmeal, and salt, and then cover with water.

Repeat this treatment every day, taking care to make the water pretty salt.

=OZOKERIT.= _Syn._ FOSSIL WAX, MINERAL WAX. This substance, which has within the last few years been utilised as a source of paraffin and the mineral hydrocarbon oils, is found in various localities in the tertiary strata, mostly occurring in, or in close proximity to, the coal measures.

But although extensive deposits of it are to be met with in Gallicia and on the slopes of the Carpathian mountains, it is by no means an abundant body. In the Austrian empire there are many large manufactories for its conversion into paraffin and the mineral oils. In our country there is we believe only one, that of Messrs Field. Ozokerit is usually met with as a brown and compact substance, occasionally yellow; however, it is sometimes black. It melts at a temperature varying from 60 to 80 C.

NEFT-GIL is a substance very similar to ozokerit, and is formed on the island of Swatoi-Ostrow in the Caspian Sea. According to Rossma.s.sler, neft-gil is treated in the following manner:--15 cwt. of the crude material is put into iron stills provided with a leaden worm, and submitted to fractional distillation, yielding 68 per cent. of distillate, consisting of 8 per cent. of oil, and 60 per cent. of crude paraffin. The oil thus obtained is yellow, opalescent, possesses an ethereal odour, and a sp. gr. of 075 to 081. Each distillation yields a quant.i.ty of a light oil boiling below 100 C., which is used for the purpose of purifying the paraffin. The crude paraffin obtained by the first distillation is tolerably pure, has a yellow colour, and can at once be treated by the hydraulic press and centrifugal machine; the oil from these operations is again submitted to fractional distillation in order to obtain more paraffin. The pressed paraffin is melted and treated at 170 to 180 C.

with sulphuric acid, which is next neutralised by means of lime, and the paraffin again rapidly distilled, then again submitted to strong pressure, and the material obtained treated with 25 per cent. of the light oil; then again melted, again pressed, and finally treated with steam for the purpose of eliminating the last trace of essential oil. The material obtained by this treatment is a perfectly pure, colourless material, free from smell, transparent, and so hard as to exhibit in large blocks almost a metallic sound. The fusing point is 63 C.

=OZONE= (Greek, ???h, I smell) is a peculiar variety of oxygen, characterised by its greater weight, its peculiar chlorous smell, its intensely active oxidising powers, and, finally, by the ease with which it pa.s.ses into common oxygen. The history of ozone may be summed up as follows:--In 1785 Van Marum observed the production of a peculiar smell when electric sparks were pa.s.sed through oxygen. This smell, which every one who has worked with an electric machine must have noticed, Van Marum regarded as the "smell of electricity," thinking that electricity was a substance. In 1840 Schonbein, of Basle, proved the existence of a definite substance, to which he a.s.signed the name of ozone, and discovered several modes of producing it, a delicate test for it, and several of its most striking properties. He subsequently added many new facts, but to the time of his death he never held a correct theory in regard to its nature. Later researches by Marignac and Dedalline, Becquerel and Fremy, Andrews and Tait, Soret, Brodie, and others, have established the true nature of this remarkable body. It is now generally admitted that it only differs from common oxygen in containing three atoms of oxygen in each molecule instead of two. In fact, as the formula for oxygen is O_{2}, that of ozone is O_{3}. It follows that ozone is half as heavy again as oxygen, and it has accordingly been demonstrated that its specific gravity is 24 (H = 1), that of oxygen being 16. All the known reactions of ozone are easily explained in accordance with this view.

Ozone may be generated in several ways. 1. By the action of electricity on oxygen or air, sparks are far less efficacious than the silent or 'slow'

discharge; but the best apparatus is the induction-tube of Siemens. This consists of two tubes, one inside the other. The inner side of the inner and the outer side of the outer tube are coated with tinfoil, and these coatings are connected with the terminals of a powerful induction-coil.

Dry air or oxygen streams between the tubes and pa.s.ses out, strongly charged with ozone.

2. M. Boillot has proposed a modification of Siemens' apparatus, which consists of two gla.s.s tubes, one fitting within the other, and each coated externally with powdered c.o.ke made to adhere by means of gelatin. The coatings of the two tubes are connected with the poles of an induction coil, and a stream of oxygen is made to pa.s.s between the tubes, and becomes thus exposed to the influence of the silent discharge, as in Siemens' contrivance.

3. Hozeau has invented an apparatus which he calls an 'ozoniser,' by means of which ozone is produced in considerable quant.i.ties. In an ordinary straight gas-delivery tube is placed a wire of copper, lead, or, better, platinum, 4 to 6 decimetres long, with one of its extremities pa.s.sing through the side of the upper portion of the tube. On the exterior of the tube is coiled a similar wire over the path of the preceding. When the two are placed in communication with a Ruhmkorff's coil, giving a 2 or 3 centimetre spark, a slow stream of oxygen pa.s.sing through the tube will be strongly charged with ozone. By this apparatus Hozeau has prepared oxygen containing 60 to 120 (once 188) milligrams of ozone per litre.

Electrolysis of water furnished only 3 to 5 milligrams, barium peroxide and sulphuric acid 10 milligrams per litre.[84]

[Footnote 84: 'Comptes Rendus' ('Watt's Dictionary,' second supplement), lxx, 1286.]

4. During certain processes of oxidation a piece of phosphorus, half covered with water in a bottle of air, absorbs a portion of the oxygen, while another portion becomes partially ozonised.

5. By plunging a clean gla.s.s rod heated to about 260 C. into a jar containing a few drops of ether.

6. By mixing very gradually 3 parts of strong sulphuric acid and 2 of permanganate of potash.

7. It has been shown that ozone is formed in small quant.i.ty during the burning of hydrogen at a jet, and in several a.n.a.logous reactions.

8. During the liberation of oxygen at low temperatures, when barium dioxide is moistened with sulphuric acid, the odour of ozone is at once apparent, and the evolution proceeds for a considerable time.

9. In the electrolysis of water the oxygen evolved consists partly of ozone, especially if the poles are small.

10. Linder has suggested an easy method for the production of ozone for hygienic purposes, which is as follows:--Make a mixture of manganese peroxide, pota.s.sium permanganate, and oxalic acid. Two spoonfuls of this powder, if placed on a dish and gradually mixed with water, will generate ozone sufficient for a room of medium size; more water is added in small portions from time to time as the evolution ceases; the powder may be kept in a bottle ready for use.

Ozone has never been isolated. By the use of Siemens' apparatus, oxygen containing, as a maximum, twenty volumes per cent. of ozone may be obtained. This represents a contraction of about 1-11th during formation.

But it is at present impossible to separate the one from the other. Ozone is entirely converted into oxygen by a temperature of 270 C. The conversion is effected more slowly at lower temperatures. Silver, iron, copper, when moistened, are oxidised on the surface immediately at ordinary temperatures by ozone.

Silver even becomes converted into a peroxide, although it will not combine with ordinary oxygen, either when moist or dry. Little or no absorption of ozone takes place when the metals are perfectly dry, except with dry mercury and dry iodine, both of which remove it immediately. It was conclusively shown by Andrews and Tait that little or no contraction followed the absorption of ozone by these or any other agents. Hence, as suggested by these observers, it seems probable that the ozone is resolved into a quant.i.ty of ordinary oxygen equal in bulk to itself, which is liberated at the moment when another portion of its oxygen enters into combination with the metal or the iodine.

Ozonised air becomes deozonised when pa.s.sed over cold manganese dioxide, silver dioxide, or lead dioxide. When ozone is mixed with peroxide of hydrogen, water and oxygen are formed. In these cases the ozone is converted into ordinary oxygen, and the peroxides into monoxides.

=Antozone=, which Schonbein surmised to be oxygen in an oppositely electrified condition to ozone, has been shown with great probability by Van Babo to be peroxide of hydrogen.