Cooley's Cyclopaedia of Practical Receipts Volume Ii Part 180

In Donkin and Gamble's patent process the substances, previously parboiled, are placed in small tin cylinders, which are then filled up with rich soup; the lids are next soldered on quite air-tight, and a small hole is afterwards made in the centre; the cylinders are then placed in a bath of strong brine, or a strong solution of chloride of calcium, which is at once heated to the boiling point, to nearly complete the cooking process; after which the small hole in the lid is hermetically sealed by covering it with solder while the vessel still remains boiling hot; the tins are, lastly, again submitted to heat in the heated bath, the duration of which is proportioned to the quant.i.ty and character of their contents, the 'dressing' of which is to be perfected by this operation.

The ends of the tins, on cooling, a.s.sume a concave form, from the pressure of the atmosphere, without which they cannot be air-tight, and the process has been unsuccessful. To determine this, the patentees expose the canisters, prepared as before, for at least a month in an apartment heated to about 100 Fahr.; when, if the process has failed, putrefaction commences, and the ends of the cases, instead of remaining concave, bulge or become convex. This is called the 'test.' By this process, which was invented by M. Appert in France about the year 1808, fish, flesh, poultry, and vegetables may be preserved for years in any climate.

Goldner's process differs somewhat from the preceding, in the employment of a higher degree of heat, more hastily applied, and not prolonged or repeated after the tins are soldered up.

Gannal's process, having for its object the preservation of butchers' meat in the fresh state, depends on the peculiarly absorbent property of the flesh of recently killed animals, above referred to. This process consists in injecting a solution of sulphate of alumina, or, better, of chloride of aluminium, of the sp. gr. 1070 to 1085 (10 to 12 Baume), into the carotid artery, by means of a syphon, as soon as the blood ceases to flow from the slaughtered animal; both extremities of the jugular vein being previously tied. 9 to 12 quarts of the solution are sufficient for an ox, and a proportionate quant.i.ty for smaller animals. A less quant.i.ty is also required in winter than summer. When the animal has been well bled, and the injection skilfully performed, it is scarcely perceptible that the animal has undergone any preparation. The injected animal is cut up in the usual way; and when intended to be eaten within 2 or 3 weeks merely requires to be hung up in a dry, airy situation free from flies; but if it is to be kept for a longer period, it is directed to be washed with a mixed solution of common salt and chloride of aluminium at 10 Baume, and then simply dried and packed in clean air-tight barrels, and kept in a cool, dry place. If the air cannot be perfectly excluded, it should be packed in dry salt, not for the purpose of preserving it, but to prevent the vegetation of bissus, as, without this precaution, the meat becomes musty from exposure and the action of moisture. Meat preserved by this process may be kept for several years, and merely requires soaking for 24 hours in water, for the purpose of swelling its pores, to give it the appearance and taste of fresh meat, fit for either roasting or boiling.

For hot climates a somewhat stronger solution, or a larger quant.i.ty of the usual one, may be injected. The use of the strong solutions ordered in some recent works, however, deprives the flesh of a portion of its apparent freshness, and makes it more nearly approach in flavour to that which has been slightly salted in the ordinary manner.

In addition to the above it may be added that both flesh and fish may be preserved by dipping them into, or brushing them over with, pyroligneous acid, and then drying them. This gives them a smoky flavour; but if pure acetic acid (Ph. L.) be used, no taste will be imparted. These fluids may be applied by means of a clean painter's brush, or even a stiff feather. A table-spoonful is sufficient to brush over a large surface. Fish and flesh so prepared will bear a voyage to the East Indies and back, uninjured.

Fish may also be preserved in a dry state, and perfectly fresh, by means of sugar alone. Fresh fish may be thus kept for some days, so as to be as good when boiled as if just caught. If dried and kept free from mouldiness, there seems no limit to their preservation; and they are much more nutritious in this way than when salted. This process is particularly valuable in making what is called 'kippered salmon,' and the fish preserved in this manner are far superior in quality and flavour to those which are salted or smoked. A few tablespoonfuls of brown sugar are sufficient for a salmon of five or six pounds' weight; and if salt be desired, a teaspoonful or two may be added. Saltpetre may be used instead of salt, if it be wished to make the kipper hard.

The well-known property possessed by ether, alcohol, pyroxylic spirit, chloroform, and certain other hydrocarbons, of averting putrefaction, has been thus applied by M. Robin:--He encloses the meat or other substances to be preserved in a gla.s.s case, along with a sponge or a capsule containing the preservative liquid, which latter is continually evolved in a vaporous condition, and exercises the preservative agency. In this way the vapours of hydrocyanic acid are found to be very efficacious. Camphor is thus employed in the MUMMY CASES in the British Museum.

It has been a.s.serted by Mr George Hamilton that in an atmosphere of binoxide of nitrogen, in the dark, flesh preserves its natural colour and freshness for about five months; and eats well provided it be boiled in open vessels, to expel nitrous fumes. See CANDYING, EGG, FISH, FRUIT, MILK, PICKLES, POTTING, PRESERVES, SALTING, SMOKING, STUFFING, VEGETABLE SUBSTANCES, &c.

=PUT'TY.= This name is given to the following preparations (when used alone. 'Glazier's putty' is generally indicated):--

=Putty, Glazier's.= From whiting made into a stiff paste with drying oil.

It is used to fix panes of gla.s.s in sashes, to fill holes and cracks in wood before painting it, &c.

=Putty, Plasterer's.= A fine cement used by plasterers, made of lime only.

It differs from 'FINE STUFF' in the absence of hair.

=Putty, Polisher's.= _Syn._ PUTTY POWDER, CALCINE; CINERES STANNI, STANNI OXYDUM CRUDUM, L. A crude peroxide of tin, obtained by exposing metallic tin in a reverberatory furnace, and raking off the dross as it forms; this is afterwards calcined until it becomes whitish, and is then reduced to powder. Another method is to melt tin with rather more than an equal weight of lead, and then to rapidly raise the heat so as to render the mixed metal red hot, when the tin will be immediately flung out in the state of 'putty' or 'peroxide.' The products of both these processes are very hard, and are used for polishing gla.s.s and j.a.pan work, and to colour opaque white enamel. See TIN.

=Putty, To Soften.= Take 1 lb. of American pearlash and 3 lbs. of quick-lime. After slaking the lime in water add the pearlash, and let the mixture be made of a consistence about the same as that of paint. When required for use apply it to both sides of the gla.s.s, and let it remain in contact with the putty for twelve hours; after which the putty will have become so softened that the gla.s.s may be removed from the frame without any difficulty.

=PUZZOLA'NA.= PUOZZOLANA, or, more correctly, PUZZUOLANA, is a volcanic ash found at Puzzuoli, near Naples. When mixed with lime it forms an excellent hydraulic cement. A good FACt.i.tIOUS PUZZOLANA may be made by heating a mixture of 3 bushels of clay and 1 bushel of fresh-slaked lime for some hours to redness. (M. Bruyere.) See CEMENT and MORTAR.

=PYRI'TES.= A term applied to several native metallic sulphides. IRON PYRITES is the best known of these.

=PY'RO-.= The term is applied to several acids that are obtained by the action of heat on other substances; as, PYROGALLIC ACID, PYROLIGNEOUS A., &c.

=PYROACE'TIC SPIRIT.= See SPIRIT (Pyroacetic).

=PYROGAL'LIC ACID.= HC_{6}H_{5}O_{3}. _Syn._ ACIDUM PYROGALLIc.u.m, L.

_Prep._ 1. From either gallic or tannic acid, heated in a retort by means of an oil bath, and steadily maintained at a temperature of about 420 Fahr. as long as crystals are formed in the neck of the retort, or in the receiver, both of which should be kept well cooled. Pure. If a much higher heat is employed, the product consists chiefly of metagallic acid.

2. From Aleppo galls, in very coa.r.s.e powder, heated in a dish covered with thin filtering paper pasted to its edge, and connected with a well-cooled receiver. Dr Ure says that the so-called Chinese galls furnish, by dry distillation, a "very concentrated solution of pyrogallic acid, which, evaporated on the water bath, yields of brown crystalline pyrogallic acid nearly 15% of the weight of the galls."

3. (Dr Stenhouse.) By sublimation from the dry aqueous extract of nut-galls, in a Mohr's apparatus, in the same way that benzoic acid is obtained from benzoin resin, observing the precautions referred to in No.

1 (_above_). Nearly pure. The product is fully 10% of the weight of extract operated on.

_Prop._ Light crystals, which, when perfectly pure, are quite white; freely soluble in water, but the solution cannot be evaporated without turning black and suffering decomposition; it strikes a rich blackish-blue colour with the protosalts of iron, and reduces those of the sesquioxide to the state of protoxide; when heated to 480 Fahr., it is converted into METAGALLIC ACID and water.

_Uses, &c._ Pure pyrogallic acid is now very extensively employed in photography. A solution of the crude acid mixed with a little spirit is used to dye the hair, to which it imparts a fine brown colour, but has the disadvantage of also staining the skin when applied to it.

=PY'ROGEN ACIDS.= Those generated by heat.

=PYRO'LA.= See WINTER GREEN.

=PYROLIG'NEOUS ACID.= _Syn._ VINEGAR OF WOOD, SPIRIT OF W., SMOKING LIQUOR, ESSENCE OF SMOKE; ACIDUM PYROLIGNOSUM, L. Impure acetic acid, obtained by the destructive distillation of wood in close vessels. It comes over along with tar creasote, and other liquid and gaseous matters.

In this state it contains much empyreumatic matter in solution; but by separation from the tar, saturation with slaked lime or chalk, defecation, and evaporation, an impure acetate of pyrolignate of lime is obtained, which, after being gently heated, to destroy part of its empyreumatic matter, without injuring its acetic acid, is again dissolved and defecated, and then precipitated by a solution of sulphate of soda, when a solution of acetate of soda and a precipitate of sulphate of lime are formed by double decomposition. The solution is next evaporated to dryness, the dry ma.s.s (pyrolignite of soda) dissolved in water, and the new solution filtered and recrystallised. The crystals of acetate of soda, obtained by the last process, yield nearly pure acetic acid by distillation along with sulphuric acid. See ACETIC ACID and VINEGAR.

=PYROLIG'NEOUS SPIRIT.= See SPIRIT (Pyroxilic).

=PYROM'ETER.= An instrument to measure high degrees of heat. WEDGWOOD'S PYROMETER, the one best known, depends on the property which clay possesses of contracting when strongly heated. PROF DANIEL'S PYROMETER consists, essentially, of a small rod or bar of platinum, which acts in a precisely opposite manner to the preceding, viz., by its expansion.

=PYROPH'ORUS.= _Syn._ LUFT-ZUNDER, Ger. Any substance that inflames spontaneously when exposed to the air.

_Prep._ 1. Neutral chromate of lead, 6 parts; sulphur, 1 part; triturate them with water, q. s. to form a paste, and make this into pellets; dry these perfectly by a gentle heat, then heat them in a closed tube until the sulphur is all driven off; lastly, transfer them to a stoppered phial.

2. (HOMBERG'S PYROPHORUS.) From alum and brown sugar, equal parts; stir the mixture in an iron ladle over the fire until dry, then put it into an earthen or coated gla.s.s phial, and keep it at a red heat so long as the flame is emitted; it must then be carefully stopped up and cooled.

3. (Dr Hare.) Lampblack, 3 parts; burnt alum, 4 parts; carbonate of pota.s.sa, 8 parts; as the last.

4. (Gay Lussac.) From sulphate of pota.s.sa, 9 parts; calcined lampblack, 5 parts; as No. 2.

5. Alum, 3 parts; wheat flour, 1 part; as No. 2.

6. (LEAD PYROPHORUS--Gobel.) Heat tartrate of lead to redness in a gla.s.s tube, and then hermetically seal it. See TARTRATE OF LEAD.

_Obs._ When the above are properly prepared, a little of the powder rapidly becomes very hot, and inflames on exposure to the air. The accession of the combustion is promoted by moisture, as a damp atmosphere or the breath. With the exception of the first and sixth, "they owe their combustibility to the presence of sulphide of pota.s.sium." (Gay Lussac.)

=PYROPHOSPHOR'IC ACID.= See DIBASIC PHOSPHORIC ACID (Phosphorus).

=PYRO'SIS.= _Syn._ BLACK WATER, WATER BRASH, WATER QUALM. An affection of the stomach, attended by a sensation of heat and the eructation of a thin, sour liquid, often in considerable quant.i.ty, especially in the morning.

The following pill will be found of service in this affection:--Powdered opium, 1/8th gr.; subnitrate of bis.m.u.th, 5 gr.; extract of gentian, sufficient to make into 2 pills. To be taken two or three times a day, before meals.

The solution of bis.m.u.th and citrate of ammonia (Liquor Bis.m.u.thi et Ammoniae Citratis, B. P.), in doses of 1/2 dr. to 1 dr., taken as above, is another medicine which may be had recourse to, should the above fail to give relief.

=PYBOTARTAR'IC ACID.= H_{2}C_{5}H_{6}O_{4}. Obtained by the destructive distillation of tartaric acid. See TARTARIC ACID.

=PYROTECH'NY.= The art of making fireworks. The three princ.i.p.al materials employed in this art are charcoal, nitre, and sulphur, along with filings of iron, steel, copper, or zinc, or with resin, camphor, lycopodium, or other substances, to impart colour, or to modify the effect or the duration of the combustion. Gunpowder is used "either in grain, half crushed, or finely ground, for different purposes. The longer the iron filings are, the brighter red and white spots they give; those being preferred which are made with a coa.r.s.e file, and quite free from rust.

Steel filings and cast-iron borings contain carbon, and afford a more brilliant fire, with wavy radiations. Copper filings give a greenish tint to flame; those of zinc, a fine blue colour; the sulphide of antimony gives a less greenish blue than zinc, but with much smoke; amber affords a yellow fire, as well as colophony (resin) and common salt; but the last must be very dry. Lampblack produces a very red colour with gunpowder, and a pink one with nitre in excess; it serves for making golden showers."

When this substance is lightly mixed with gunpowder and put into cases, it throws out small stars resembling the rowel of a spur; this composition has hence been called 'spur fire.' "The yellow sand, or glistening mica, communicates to fire-works golden radiations. Verdigris imparts a pale green; sulphate of copper and sal ammoniac gives a palm-tree green.

Camphor yields a very white flame and aromatic fumes, which masks the bad smell of other substances. Benzoin and storax are also used, on account of their agreeable odour. Lycopodium burns with a rose colour and a magnificent flame; but it is princ.i.p.ally employed in theatres to represent lightning, or to charge the torch of a Fury." (Ure.) See FIRES (Coloured), FLAME COLOURS, GUNPOWDER, STARS, ROCKETS, &c.

The following substances are in requisition by the Pyrotechnist:--

ZINC. This metal is employed in the form of fine powder, which is obtained as follows:--The metal, scarcely melted, is poured into a hot mortar, where it is reduced to powder, being kept during the operation at a temperature of 401 F. It is then sifted to remove any particles which may have escaped contact with the pestle.

COPPER. This metal may be obtained in a state of minute division by precipitating it from a solution of sulphate of copper by means of iron, the precaution being taken of using a large quant.i.ty of iron. The precipitate, after being well washed, is dried between folds of blotting paper, and kept in well stoppered bottles.

IRON-SAND. A quant.i.ty of sulphur is melted in a crucible over a slow fire, and when it is quite fluid, iron filings are thrown in while the whole is being stirred. The crucible is removed from the fire, and the contents are rapidly stirred until cold. The material is then rolled on a board till it is broken up as fine as corned powder, after which the sulphur is sifted out.

SODA POWDER. This powder is prepared with the same precaution as ordinary gunpowder, the proportions which answer best being: