Chapter VII (9)

To trace the steps of the process from its commencement, let us imagine a vessel of water placed over the fire, and receiving constantly a supply of heat from that source; the effect is, that its temperature gradually rises from about 50° or 60°, the usual warmth of ordinary water, to 212°, the point at which boiling takes place; but before it reaches that height, a number of bubbles may be observed forming on the sides of the vessel; these gradually increase in size, and when they become sufficiently buoyant, quit their position, rise to the surface, and escape; they consist of air previously dissolved in the water, and which is expelled by the increased heat. Water which has been boiled and allowed to become cold, without much exposure to the air, fails to re-absorb the quantity it previously contained, and consequently has its character somewhat altered. Thus, it freezes more readily than water which has not been boiled, in consequence of the air not having to be expelled in the act of solidifying, as is usually the case: hence, the ice from boiled water is free from those numerous air bubbles which are always to be observed in common ice. It possesses also a mawkish unpleasant taste, and is totally unable to preserve the life of any aquatic animal. The presence of this minute quantity of air in ordinary water, is very essential to its utility. Faraday found that water, _totally_ destitute of air, does not boil in the usual mode, but when heated to the boiling point, it at once, with an instantaneous and violent explosion, passes into the form of steam. This strange fact, which shows upon what small, and, apparently, trivial circumstances, the comfort—nay, we may truly say—the existence of man depends, is strikingly shown by a very ingenious experiment, devised by that most celebrated chemist. He took a piece of Wenham Lake ice (which, from peculiar local causes, such as being formed from spring water, is totally destitute of air), and melted it under a covering of sweet oil; this prevented the absorption of any air during the liquefaction; on continuing the heat, the water rose in temperature, and on reaching the boiling point, suddenly burst into steam, with an explosive power, sufficiently great to scatter the glass vessel in which the experiment was made into fragments; and had it not been for a protecting covering of wire gauze, very serious effects might have ensued.

From the precipitation of the dissolved chalk present in most kinds of water, a cloudiness or slight turbidity is always to be observed in boiled water.

After the escape of the air, bubbles of steam, at first very small in size, are formed at the bottom of the vessel, those formed at first are at once cooled from the whole water not being of an equal temperature, and are condensed before they reach the surface: this very rapid and successive condensation of numerous small bubbles gives rise to that peculiar vibration which occasions what is termed the _singing_ of the tea-kettle, and which, as is well known, is indicative of its approach to the boiling point; when the whole water is uniformly heated, this effect no longer occurs, but the bubbles of steam rise to the surface and escape. After having been heated to 212°, the temperature of water no longer rises; it is not possible, under ordinary circumstances, to increase the temperature in the slightest degree, for all the extra heat that is given to boiling water merely produces an increased quantity of steam, by which it is carried off, without affecting the heat of the remaining water. This is a matter of considerable practical importance in cookery; and it should be always borne in mind, that the most gentle simmer is as efficacious in cooking as the most violent boiling, for the degree of heat in both cases is precisely the same, so that after having once raised the water to the boiling point, the most moderate fire is sufficient in ordinary cases to keep it there; by attention to this point, a most enormous saving may often be effected in the consumption of fuel, although this is a consideration that will be more fully entered into in a subsequent article. Thick liquids, which do not readily permit the escape of steam or the rapid motion between the particles of the fluid, may, however, be readily heated at the part exposed to the fire to a much higher degree, whilst those portions not immediately in contact with the heat are much colder; from this cause they are very apt to be charred, and if articles of food, they are totally spoiled. To avoid this effect, recourse may be had to the _bain marie_, which is simply the same contrivance that may be observed in a carpenter’s glue-pot, applied to the preparation of articles of food, being merely an inner vessel to contain the substance to be heated; this is placed in an outer one, the space between the two containing water. On placing this on the fire, it is obvious that the substance in the inner vessel, being heated solely by the boiling water, cannot possibly become burnt; this most useful contrivance is adopted in all first-class kitchens, and is equally indispensable in the chemist’s laboratory; by its aid, soups, gravies, &c., can be kept hot any length of time without risk, preserves made without burning, &c.; the chief precautions required in its use are, that the inner vessel should be thin and formed of metal, so as to allow the rapid transmission of heat from the boiling water, and care should be taken that the outer vessel does not boil dry. One serious disadvantage attends its use as ordinarily employed, it is, that it is impossible to heat substances in it to the boiling point, for the water itself is only at that temperature, and the substance in the inner vessel is always a few degrees below. This evil may, however, be entirely obviated, by using a solution in the outer vessel, which boils at a higher temperature than 212°, and which will therefore raise the inner vessel and its contents to that point; thus, if the water be made to dissolve as much common salt as it is capable of doing, it will not boil until it is heated to 224°; or if it is saturated with sal-ammoniac or nitre, the heat will rise 12° or 14° higher. We need scarcely say that the first of these substances will be found a very useful and economical addition to the _bain marie_. When chemists require a still higher temperature, they have recourse to a bath of olive oil, which is capable of bearing a degree of heat as high as 500°; but its extreme danger over an open fire entirely precludes its use in any culinary operation.

The mode of conducting the operation of boiling should not be uniform, but vary with the different purposes required. Thus, in the case of meat, a temperature of 212° hardens, instead of softening, two of the substances which it contains; namely, the fibrine, or material forming the chief part of the muscular fibre, and the albumen, or portion which is analogous to white of egg; if, on the contrary, meat is cooked by means of water at a lower temperature, the most nutritious parts are dissolved out, and the solid food left comparatively innutritious. The celebrated German chemist, Liebig, proposes the following plan:—he recommends that a piece of meat of considerable size should be taken and plunged into perfectly boiling water, over a good fire; that the water should be kept boiling for a few minutes, and then a portion of cold water, equal in quantity to about one-half of the boiling water, should be thrown in: this will reduce the temperature to about 160°, at which point the meat should be kept until thoroughly done; which, however, takes a much longer time than in the ordinary mode.

The object of this mode of proceeding is, in the first instance, to harden the exterior of the meat, converting it into a sort of crust, which prevents the escape of the nutritious juices into the water, whilst the long continuance of the gentle heat afterwards cooks the interior without hardening either the albumen or the fibrine. Of course, where the object of boiling is to make soup, the opposite plan must be had recourse to; the meat should be in small instead of large pieces, put on in cold water and very slowly heated, so that all the soluble parts may be dissolved before the fibre is hardened by the action of boiling water.

In boiling eggs, the effect of heat in hardening the albumen is well known; by being suddenly plunged into boiling water, the outside is hardened to the greatest degree of which it is capable, and is thereby rendered extremely difficult of digestion, whilst the inside is barely warmed; if, on the contrary, they are placed in cold water, which is then raised to the boiling point, removed from the fire, and allowed to stand about a minute (or two, if required to be well done), it will be found that, instead of having an almost leathery consistence, the white will be uniformly partially hardened, and will furnish a much more pleasant and digestible article of diet; the improvement, in fact, is so great, the common eggs cooked in this manner very nearly approach new-laid ones in quality.

If the operation of boiling has to be performed on any substance containing starchy matters—as potatoes, rice, flour, &c., then the heat must, on the contrary, be raised to a sufficient degree to burst the little grains of which the starch consists, and liberate the interior nutritious portions, before it can become fit food for man; uncooked starch not being readily or easily digested. And even in the case of those vegetable-feeding animals whose power of digesting such substances surpasses that of man, there is the greatest advantage to be derived from the use of cooked food, as the most intelligent and scientific farmers at the present day well know; and we would strongly urge on those of our readers who keep pigs, to try the experiment of baking the potatoes they give them, for this process, like boiling, has the effect of bursting the starch grains; they will find the effect to be that the food will go much further, all of it being digested, and that the quality of the flesh will be very materially improved.

IX.

ECONOMY OF HEAT.

Perhaps few of our readers are aware of the extraordinary wastefulness of our usual processes for obtaining artificial heat; at the most moderate computation, seven-eighths of the warmth produced by an open fire, pass up the chimney, and are entirely useless; and according to other estimates, which we regard as being nearer the truth, fourteen parts out of every fifteen are thus uselessly wasted. In no other civilized country in the world, except in England, is such an enormous waste of fuel allowed; nor would it be the case here, were it not that the comparatively low price of fuel, from the abundance of coal, has led to the extravagance. It may be asked, what are the defects of a common fire-place that render it so wasteful, and in what way is the heat carried off? In reply it may be stated, that one-half the heat produced passes away with the smoke and heated air arising from the fire, a quarter is carried up by the draught of cold air from the room, which, flowing around the fire and between it and the mantel-piece, rises with the smoke. Again, the soot which passes away is unburned fuel, and is, therefore, useless; and a large portion of heat is thrown downwards on to the ashes, and is wasted; whilst the iron, of which the grates are generally made, conveys away a very considerable quantity. On the continent of Europe, where the cold in winter is much more intense than in this country, and where fuel is considerably dearer than with us, the production of heat is more economically managed—stoves of very admirable construction being constantly had recourse to, both for the purpose of producing warmth and for cookery. It is to the latter application of heat that we must mainly confine ourselves in this paper, and having been at some considerable pains in examining the various stoves and ranges now to be obtained in this country, we place the results of our experience before our readers.

The cooking-stove common on the continent, consists of an enclosed fire-pan, with a grating below and a lid at the top for the supply of fuel; this is enclosed in an oven, supported on the floor of the room by feet, and which is heated by the warmth thrown out by the sides of the fire-pan, and also by a flue spreading over the top, which is thus heated; whilst the upper surface of the flue forms a hot plate, on which many saucepans, &c., can be kept boiling, and any vessel can also be placed over the fire by the removal of the lid. As the draught is under perfect control, the fuel is slowly consumed; and the stove affords means of baking, boiling, frying, and stewing, at a very small expense.

Some years since, a modification of this contrivance was introduced here, under the title of the Bruges Stove, by Messrs. Cottam & Hallam, Oxford Street. But it had one deficiency, which, in English eyes, overwhelmed all its advantages, viz., that no fire was visible, and also that boiling, toasting, and roasting, were, not to be performed by its means.

Those of our readers who visited Prince Albert’s Model Cottages opposite the Exhibition, may have noticed a stove, looking very much like a long oblong box, standing on four legs, having two doors in the front, one opening into a large-sized oven, the other disclosing the fire-grate, which was fed by the removal of a lid at the top—the draught from the fire passed over the oven, heating it and the hot plate above. This stove combines all the advantages of the continental cooking stoves, with the cheerful appearance of an open fire; at the same time, by closing up the fire-place door, it is converted into a close stove, with an excessively small consumption of fuel. From experience in its use, we can state that it bakes admirably, either bread or large joints of meat; at the same time, it boils a saucepan and steamer over the fire-hole, and also four large or six smaller saucepans on the top of the hot plate; it fries well, and broils before the fire, and this, with less than one-half the fuel that was employed to do a portion of the work in the range which it has deposed. The _bain marie_, the use of which was described in our last article, and which is so excellent a means of keeping soups, gravies, sauces, &c., hot without burning or drying them up, is readily used with it; and the _sauté_ pan, or deep frying-pan, which is employed as a preliminary operation in most French-made dishes, is conveniently used. This contrivance (which is absurdly termed by our cooks the _sooty_ pan) derives its name from the verb _sauter_, to jump—the meat being rapidly turned over and browned previous to stewing. The only disadvantage attending the use of the stove is, that it is not calculated for roasting; but every other operation in cooking, it performs infinitely better than a common fire, and that at a consumption of less than half a bushel of coke per day. This stove, which is termed the Cottager’s Stove (_Fig. 1_), is made by Messrs. Benham, Wigmore Street.

Those who object to a stove of this character, preferring a range, even at a greater sacrifice of economy, should still be somewhat guided by correct principles in their selection; a range surrounded by iron is an absurdity, as the metal conducts away the heat rapidly; it should be backed and lined with fire-brick or Welsh lumps, which throw out the heat with great power. In an open fire-place, the active combustion is wanted in front for roasting, and there only should air enter the fire; in most ranges the air enters below, causing the greatest heat to be thrown upon the ashes. It may be thought that closing up the bottom would produce the same effect as allowing it to be choked up with ashes in a common grate, deadening the fire; this is not the case with a properly constructed range, backed with a slanting back of fire-clay; the ashes can be readily removed at the bottom, and from all the draught being in front, there is a bright fire at the place where it is required. The range in the Reform Club, which was erected by Messrs. Benham, under the direction of the late Sir Charles Barry, the architect of the new Houses of Parliament, is of this kind, and it is, perhaps, the finest in the world. Our common ranges are far too deep—the burning of such a mass of coal being useless. One of the best constructed ranges, of a small size, is Nicholson’s Cottage Range, that obtained the prize given by the Royal Agricultural Society; it is free from the objections raised above, and comprises an oven and boiler; is economical in price and efficient in use. Unlike the Cottager’s Stove, it is a fixture, requiring setting, and, therefore, is more a subject for the landlord’s than the tenant’s consideration. It may be seen in London at Pierce’s, in Jermyn Street. The improvements in the use of fuel have mainly arisen from philanthropic individuals directing their attention to improving the comfort of the working classes, and the improvements here made have been copied for the use of the wealthier class, by both the makers above named, as well as by others.

In situations where gas is to be obtained, it forms a ready, and, for some purposes, very economical means of obtaining heat; its economy does not arise from its cheapness compared with other means, but from the fact that it need not be lighted till the instant it is required, and can be as quickly extinguished when it has done its required duty; for heating any vessels containing liquids, especially if the heat is required to be only of short continuance, gas will be found extremely advantageous; a ring burner, constructed as shown in _Fig. 2_, less than three inches in diameter, will quickly boil a gallon of water in a metallic vessel; burners of this description are usually used in the laboratory, surrounded by a case made of sheet-iron or tinned plate, as _Fig. 3_; this serves to support the vessel to be heated, to steady the jets of flame, and to conduct every portion of hot air against the bottom; the door also gives a ready access to the burner for the purposes of lighting the gas.

For the domestic use of gas in heating, we believe there is no contrivance so useful as the following:—A circular hole, from two to four or more inches in diameter, is cut in the dresser, through which is passed a sheet-iron tube, supported by three little elbows; this tube projects a few inches above the table, and about a foot and a half below; its lower end is open, and into it projects a gas pipe, furnished with a stop-cock; the upper extremity is covered with a sheet of wire gauze, similar to that used for blinds, on which, as shown in _Fig. 4_, may be placed some pieces of pumice-stone, surrounded and kept together by a broad ring—neither the pumice-stone nor the ring, however, are essential parts of the contrivance. The action of this arrangement is as follows:—When the gas is turned on it escapes from the pipe, rising through the tube, and mixing with the air contained within it; this mixture then escapes through the wire gauze, and may be lighted on its upper side, without passing through it to the gas below; the flame should be perfectly free from smoke, which indicates too much gas—should be pale, colourless, and not soil any bright metal placed in it; if the flame is in the slightest degree yellow it will do this, and then the gas should be partly turned off—on the contrary, if there is not enough gas, the flame will be extinguished. When lighted, the pumice becomes red-hot, and throws out a great heat; when used in boiling, the vessel should be supported a short distance over the flame by a trivet; if it is made to rest on the top of the ring, and is sufficiently large to close it entirely, the current is stopped and the flame extinguished, whilst the unburned gas still escapes below. This contrivance is most useful, it is lighted in an instant, is perfectly free from smoke, no unburned gas escapes, it throws out great heat, and may be employed to heat bright tools with much more convenience than a charcoal fire: the objections to its use are, that in burning it produces, as all gas does, a quantity of carbonic acid gas, deteriorating the air, and that the flame cannot be very much enlarged or diminished, so that if fires of different power are required, two or more of the contrivances must be put in order. Otherwise, the instantaneous action, small cost, great heating power, and cleanliness of the plan, strongly recommend it. In summer weather, in many small families, it can be made to dispense altogether with the use of a fire. By a little variation, the whole contrivance may be made to stand on the table like _Fig. 2_; in this and other cases, vulcanized India-rubber will be found to form by far the best kind of flexible tube, being quite impervious, very durable, and excessively pliant. Those who wish to try the experiment of heating on this plan, may readily do so by covering the top of the glass chimney of any common burner with a piece of wire gauze, folding it over the sides; the gas may then be turned on, and lighted above the gauze, after it has mingled with the air in the chimney; a small burner, however, does not afford sufficient gas for the purpose, and there is consequently too much air, and the flame is weak and liable to go out.

We cannot conclude this article on heat, without entering our most earnest protest against _all_ those injurious contrivances for burning charcoal without a flue; the use of charcoal-braziers in a large kitchen is not to be recommended, but a charcoal stove in a dwelling-room is most objectionable. Charcoal, in burning, produces carbonic acid gas, an invisible and therefore insidious poison, which is so deadly in its effects, that if the air of a room contains but one-tenth of its bulk, the breathing of it for a short time is fatal. Every pound of charcoal, in burning, produces more than three pounds and a half of this deadly gas, and the ill effect of charcoal stoves may be readily imagined.

In Paris, in the years 1834 and 1835, there were 360 cases resulting from the fumes of charcoal, of which more than 260 were fatal. In order to test the effects of these stoves, Mr. Coathupe, of Wraxall, shut himself up in a close room containing eighty cubic yards of air, with one of them in action. In four hours he was seized with giddiness, which, in an hour’s time, became most intense; he then had the desire to vomit, but not the power; this was followed by an utter loss of strength, throbbing at the temples, and agonizing headache, but no sense of suffocation; finding that the experiment was becoming dangerous, he essayed to open the window, but had the greatest difficulty in so doing; and when his wife came into the room, he was found in a speechless state, in which he remained for some time.

In a fatal case, which happened in St. John’s Wood, where two girls were killed by the use of one of these stoves, the writer found, on investigation, that the quantity of carbonic acid produced was capable of rendering poisonous the air of a room ten times the size of the one in which it was used; and yet the maker is guilty, even to the present time, of the moral turpitude of recommending these as fitted for burning in a close room. Men who, knowing the poisonous effects of these stoves, still sell them, recommending them as wholesome, with the deliberate assertion that their prepared fuel, which is merely charcoal disguised, is not deleterious, evince a much more lively interest in the state of their own pockets, than in the lives of their customers.

Let it not be imagined that the case of Mr. Coathupe is only a solitary one; the action of burning charcoal is of the same deleterious nature on all persons. In January, 1836, seventy people suffered the same symptoms, though in a milder degree, in the church at Downham, in Norfolk, where two of these dangerous contrivances had been introduced: and in the _Annales d’Hygéine_, tome xi., will be found an account of the suicides in the department of the Seine in ten years, these were 4595 in number, of which 1426 deaths were produced by burning charcoal. We would again recommend our readers under no circumstances, however much they may be recommended by false assertions, to admit stoves without flues into their houses. In France, the deaths from charcoal have been mostly suicides, as, from their deadly effects, they are never used in close rooms. But in England, persons are often ignorant of the action of charcoal fumes, and relying on the word of some stove makers, whose “conscience,” as Milton says, “is their maw,” the numerous deaths have been chiefly those of innocent persons, victims to the cupidity of the makers.

X.

CLEANING AND DISINFECTING.

In our previous papers on Domestic Manipulation, we have several times given directions as to the best mode of conducting processes for cleaning various articles, such as bottles, glass, &c. What remains, therefore, under this head, is to furnish hints for cleaning miscellaneous articles, which have not been included under previous accounts; and the very important process of disinfecting, which may be regarded as a medical cleaning, falls, naturally, into the same chapter. As the substances to be submitted to the process of cleaning vary greatly from one another, we shall find it more convenient to throw our remarks into the form of miscellaneous hints, than to arrange them in a chapter for consecutive reading.

IRON-WORK which is exposed to wet, rusts rapidly; it is usually preserved from the action of moisture either by covering it with two or three coatings of paint, as is customary in large out-door works, or by brushing it over with a varnish termed Brunswick black; this plan is usually followed in the case of smaller substances used in-doors. A very superior plan of protecting small iron goods from the injurious action of wet, is to heat them a little below redness, and whilst hot to brush them over with common linseed oil, which is decomposed by the heat, and forms a thin, very firm coating of varnish, which is quite impervious to water, and unlike paint or Japan-black does not chip off. It is evident that this plan can only be adopted in a limited number of cases, but where it is available we very strongly recommend it.

FLOOR BOARDING and other wood-work is exceedingly apt to be stained by various substances spilt upon it. Ink stains, for instance, are extremely obstinate; they withstand washing many times, and at last turn to a rusty iron colour, from the application of the alkali of the soap. Both the black stain of recent ink and the rusty iron-mould may be removed by the action of oxalic or muriatic acid. As wood is not likely to be injured like cloth or linen, muriatic acid may be used, being the cheaper, and it should be diluted with two or three times its bulk of water, and applied until the stain is removed. Grease which has been trodden in, or has remained a long time, should be first softened by the application of a little turpentine, and then it will be found to yield much more readily than it otherwise would to the action of fuller’s earth and pearlash or soda. Fruit stains are quickly removed by the action of a little chloride of lime, mixed with water, and applied until the desired effect is produced. It should be borne in mind that all vegetable colours are utterly destroyed beyond any restoration, by the energetic action of this agent.

PAINT, when soiled, is readily cleaned by soap and water; soda and pearlash are frequently employed, but they act by removing a portion of the paint, and if not thoroughly washed off with clean water afterwards, they will be found to soften the whole. Caustic alkalies, such as the solution for washing on the new plan, will rapidly dissolve paint, and are therefore inapplicable for cleaning; they may, however, be usefully employed in removing paint from wood, where such an operation is requisite.

PLATE may be cleaned by rouge, or if this is not readily obtained, by washed whiting; this is readily made by stirring some whiting up with water, then allowing the larger particles and the grit to subside, and pouring off the water charged with the finer powder, which is allowed to settle, and dried for use. When plate is very much stained, it may be cleaned with putty powder, but this preparation would soon wear away the silver if used frequently or unnecessarily. It may be mentioned, that this substance is not made from putty, as its name might seem to imply, but is a rust or oxide of tin, obtained by heating the metal.

JAPANNED GOODS, such as tea-boards, should not have boiling water poured upon them, but should be washed with warm water, and polished with a piece of wash-leather and fine flour.

KNIVES.—The common wooden knife-board wears out the knives very rapidly, it is therefore much better to employ a piece of buff-leather to cover the board; for very superior cutlery emery powder should be used instead of Bath brick. Whatever the material of the board, it will be rapidly spoiled by cleaning the backs of knives upon the edge of the board; to prevent this evil, a small piece of leather should be fixed at one end to clean the backs upon. We have seen several knife-boards lately, covered with a material formed of India-rubber and powdered cork, which was manufactured as a substitute for floor-cloth, and sold under the name of _kamptulicon_; but we have had no experience in their use.

STEEL FORKS are readily cleaned by having a pot of damp moss or hay, with some sand intermixed, into which they may be repeatedly thrust. If knives or forks get an unpleasant taint which cannot be removed readily, they may be plunged into the mould of the garden, which has a very absorptive power, and rapidly removes such odours.

BEDSTEADS may be freed from vermin by brushing them over in the cracks with a mixture formed of one ounce of corrosive sublimate, dissolved in half a pint of oil of turpentine, and the same quantity of any spirit, such as strong gin or whisky; this effectually prevents their harbouring. But when first applied, it possesses a disagreeable odour from the turpentine, and great care must be taken with it as it is excessively poisonous, although from its disagreeable smell it is not likely to be swallowed accidentally. It has been found that the presence of the odour of creosote (in vessels which have been used in carrying railway sleepers prepared with this substance, to prevent their rotting) has effectually driven away these enemies to our nocturnal peace. Unfortunately, the odour of creosote is very powerful and unpleasant, but there may be cases in which it may be applicable. On the whole, constant and unremitting cleanliness, and the employment of iron bedsteads, which are now manufactured of the most elegant forms, are the best means of getting rid of these pests.

As stated in our first article, the operations of dusting, scrubbing, &c., though in strictness, Domestic Manipulations, hardly come within the limits of this series of papers; we pass on, therefore, to the more important operations of disinfecting. Various means have been proposed of lessening or utterly destroying the infectious emanations that proceed from persons in certain diseases, and which frequently have the power of attaching themselves with greater or less tenacity to such articles as wearing apparel, &c. Generally speaking, the presence of a good system of ventilation is sufficient to prevent taking any infection. When rooms are properly aired, a disease can seldom be caught more than a few feet from a patient; or even in the case of those most infectious disorders, scarlet fever and small-pox, it seldom spreads more than a few yards; but if the air of a room is confined, the infection is concentrated, and becomes much more certain in its action.

Downy and fibrous materials readily receive infection; it may, in fact, in many instances, be folded up in them, and so retained almost any length of time; but if they are thoroughly exposed to a free current of air, it is dissipated in a short time. It should be mentioned, that infectious diseases are more readily received in certain states of the body; thus, fear, timidity, mental anxiety; and such states of mind, by lowering the general tone of the system, render it much more liable to contract infectious or contagious diseases; a state of exhaustion from bodily fatigue, or from hunger, has the same tendency. Infection is also more readily received through the lungs than through the skin; therefore, it is important never to receive the breath of a patient, and, as a sailor would say, always keep to the windward side of him. Amongst the domestic disinfectants, vinegar has a great reputation, but undeservedly so; its only action is to overpower, by its odour, the smell of a sick-room—as a destroyer of the peculiar influences that engender disease, it has no power. Burning substances act in the same manner. Burnt brown paper, fumigating pastiles, tobacco, only act by substituting one smell for another. The ridiculous practice of carrying about a piece of camphor is very common, and is perfectly inefficacious. If it has any action at all, it must be an injurious one; for camphor is a stimulant, and its constant inhalation must tend to lower the system, and so produce the very evil it is supposed to remedy.

The best means of preventing infection, are ventilation and cleanliness in every particular. The best means of destroying it are those powerful chemical agents which have the power of uniting with the hydrogen which is supposed to form part of the infectious substances. Nitric acid gas, formed by pouring oil of vitriol on nitre or saltpetre, has been used; but though efficacious, it possesses several disadvantages, being irritating to the lungs, corrosive to metal-work, and also, when largely employed, very expensive.

The most powerful, easily controlled, and in every sense the best disinfectant, is chlorine gas. This agent at once destroys every trace of infection in all substances submitted to its action. Its formation is perfectly under control, and goes on in a gentle manner for days together, without requiring care or attendance. We consider that the slow liberation of chlorine is far superior to the employment of chloride of lime, which gives forth the gas in a modified form.

In our own experience, we have employed it to destroy various infections, and always with complete success. In one case of a school where scarlet fever had returned after several attempts at purification, and in the last instance with a fatal effect, we used chlorine, and effected the complete removal of every trace of the disease. Various modes of liberating chlorine are known to chemists; but, for such purposes as the present, where a slow, uniform, and constant action is required, there are none equal to the following plan:—One pound of common table-salt is to be intimately mixed by stirring with an equal weight of a substance called manganese, which may be readily obtained from any good chemist. Small portions of this mixture should be placed in shallow pans (the saucers of common flower-pots answer the purpose exceedingly well); and upon them should be poured a mixture of oil of vitriol (sulphuric acid) and water, the quantity required for the above weights, viz., for one pound of each ingredient, being two pounds of oil of vitriol and one of water, both by weight. These should have been previously mixed in a wooden vessel, being stirred by a wooden lath, and allowed to become cool before being poured on the salt and manganese, as the mixing of the acid and water generates great heat. Too much care cannot be taken with the acid, as it is excessively corrosive in its nature, and destroys most substances with which it comes in contact. When these materials are all mixed, chlorine is slowly evolved for a period of three or four days, and in so gentle a manner, that not the slightest irritating or unpleasant effect is produced. If it is wished to cause the more rapid production of gas, the saucer may be placed over a basin of boiling water, or upon a hot brick; but the slow generation for a considerable length of time is what should be more especially aimed at. It is needless to say, that all substances supposed to have been contaminated, should be spread out so as to receive the influence of the gas; the bed linen, and all woollen garments, being exposed by being spread out on chairs, lines, &c.; the drawers and cupboards opened; and whilst the disinfecting is in actual operation, the windows and doors should be kept shut, to prevent the dissipation of the chlorine. It is found that two ounces of manganese, with a proportionate quantity of the other materials, is sufficient for a room twenty feet wide, forty feet long, and twelve feet high, which contains 20 × 40 × 12 = 9600 cubic feet.

It may be mentioned, that breathing chlorine in this highly diluted state is decidedly the reverse of injurious to the general health; although, in a concentrated form, or even unless very much diluted with air, it is irritating in the highest degree; but so very innoxious is it in the very dilute state, that it is occasionally prescribed for the inhalation of consumptive patients.

For the satisfaction of those who rely on the authority of a great name, it may be stated, that chlorine used in the manner here recommended was employed, with complete success, by one of the most illustrious of our English chemists, in the case of the Millbank Penitentiary, when a violent and fatal disease broke out there. The operator in this case was FARADAY, than whom there can be no higher authority.

It may occasionally be found more convenient to use another mixture for the liberation of chlorine gas, in which case the following may be employed:—One part of manganese is to be drenched with four parts, by weight, of muriatic acid (the spirits of salts of the shops), mixed with one part of water. The gas is evolved slowly in the cold, and rapidly if assisted by a gentle heat. This process is rather more expensive, and possesses no advantage over the one previously described.

XI.

FERMENTING AND DISTILLING.

In ordinary language, the term fermentation is employed to signify the peculiar changes which take place when a solution of sugar, or any vegetable substance containing saccharine matter, is converted into spirit—this, however, is only one of many such kinds of action, which are well known to chemists. The most important fermentations are the saccharine fermentation, when sugar is formed by a change taking place in starch: the vinous, when spirit is formed from sugar; and the acetous, in which vinegar or acetic acid is formed from spirit.

The saccharine fermentation, or the formation of sugar from starch, is interesting, though it does not influence such operations as are included in our Domestic Manipulations. If starch is dissolved in water, a little wheat flour added, and the whole exposed to a moderately warm temperature, it will be found that after a few days, varying in number with the degree of warmth, the starch has disappeared, and the liquid has become sweet, from the formation of sugar. The same change takes place with much greater rapidity, if starch is boiled with a solution of malt, which contains an active principle called _diastase_, capable of bringing about this fermentation in a short time. The formation of sugar from starch is an operation which constantly occurs in all growing seeds, the effect being to change an insoluble substance such as starch, into one which is capable of being dissolved in the juices of the young plant, and nourishing it during the early stages of its growth. In the operation of malting barley, the change is induced artificially, for the purpose of producing sugar in the malt, which is afterwards made to undergo the second kind of fermentation, namely, the vinous, or that in which spirit is produced.

When sugar, either that which naturally exists in many plants, or as formed from starch as just mentioned, is dissolved in water, so as to form a moderately weak solution, and the whole exposed to a degree of warmth varying from seventy to eighty degrees, it rapidly undergoes a remarkable change, provided a small quantity of any vegetable ferment is present—such as yeast, or the juice of the grape or of many other fruits. The sugar wholly disappears, and is resolved into two substances—one a gas, termed carbonic acid, which escapes giving rise to a slow effervescence; and the other, a portion of spirit, which remains in the liquid. This kind of fermentation is much more difficult to prevent than to establish; in making syrups, it is found specially annoying; for if the quantity of sugar used is too small, the syrup is certain to ferment and spoil; and if too much is added, it crystallizes out in the solid form; as a general rule, however, it is found that two parts, by weight, of sugar, to one part, by weight, of water or other liquid—such as the juice of fruits, made into a syrup by boiling for a short time—neither ferments nor crystallizes.

In the act of fermentation the spirit produced by the process last described is changed into acetic acid, or vinegar. Here, also, the presence of some substance capable of commencing the fermentation is requisite, for pure spirit and water will not undergo the change. The ferment employed may be the vinegar-plant—or it may be a little vinegar, which may have been previously formed.

For the rapid progress of the acetous fermentation, a high temperature is requisite, even as great as about eighty-six degrees, and free exposure to air is essential. The best vinegar is that made from weak wine, at Orleans; the plan followed is to introduce a portion of vinegar into the vessels, adding the wine at intervals, and never quite emptying them. In this country, a weak beer is brewed, without hops, for the purpose of making vinegar, and a small quantity of diluted oil of vitriol is added, after the vinegar is formed, to destroy the mouldiness that is otherwise apt to be present. Vinegar may be formed from any weak spirituous liquid; but it should be borne in mind that two circumstances are essential to success, namely, a high summer temperature, either natural or artificial, and free exposure to air.

The process of distillation is one which is used for separating liquids from each other which boil at different degrees of heat. In domestic economy, it is most frequently employed to obtain spirit, more or less flavoured, or scented, with some volatile essential oil. The apparatus commonly used is the still, for boiling the liquid to generate the vapour, and a long spirally-twisted tube termed the worm, which is placed in a tub of cold water, and through which the steam passes to be condensed. The worm is the most objectionable part of the modern still; its great evil is the difficulty with which it is cleaned, so as to prevent one strong-flavoured substance spoiling those which are distilled afterwards. If the coils of the worm are not very numerous, a bullet, with a string attached, may be passed through it, and a sponge or small bottle-brush, fastened to the string, may be worked backwards and forwards; but if there are several coils, it will be found impossible to do this, from the resistance caused by friction. In this case, the only plan is to close one end of the worm with a cork, and fill it with a solution of caustic alkali, allowing it to remain for some hours, and repeating the application with fresh liquid, if it be required.

In Germany, the worm is being superseded by an excellent condenser, which is so superior that we are induced to give a sketch of it, hoping that it may lead to its adoption in this country. The vapours from the still pass into the tube A (_Fig. 1_), by which they are conducted into B, a hollow globe, made to unscrew at its centre. The vapours, passing along the tube C, are condensed, and the distilled liquid drops from D. The pipe E should convey a constant stream of cold water to the bottom of the tub, and this, rising as it is warmed by extracting heat from the tubes and globe, should escape by F. All the tubes being straight, it is obvious that they can be readily cleaned from their ends.

In the laboratory, distilling is most frequently performed with vessels termed retorts, or even from flasks; but as these are not very applicable to domestic purposes, we pass them over.

In domestic practice, the still is usually employed to obtain some water or spirit flavoured with essential oil, or the oil itself, and the process should be slightly modified so as to suit each case. The vegetable substance should not be placed on the bottom of the still itself, as in that case it might become burnt, and so give an unpleasant flavour to the whole; but a bottom of wickerwork should be placed in the still in the first instance for it to rest upon, or a perforated board. The substance to be distilled should be placed in the still, covered with water, for some hours before the fire is lighted; no more water being added than sufficient to cover it, if the preparation of oil is the object.

Herbs, for distilling, should be collected on a dry day, and—unless the oil resides in the seeds, as in the case of caraway, anise, &c., or in the flowers, as in the rose, lavender, &c.—just before the flowers have opened, as at that period there is the greatest quantity of essential oil in the plant. All plants cultivated for distillation, should be grown in a situation where they can receive a full amount of sun-light, as shade or darkness very much tend to prevent the formation of essential oil.

The liquid which comes out of the worm, is a mixture of water highly flavoured with the substance, and some undissolved oil; this latter is sometimes heavier and sometimes lighter than water, either sinking or floating; in the latter case, the oil may be readily separated by filling a bottle with the mixture, and when the oil has collected at the top, carrying it off by a few threads of cotton placed as in _Fig. 2_, taking care that they are moistened with oil before arranging them. The cotton acts as a syphon, and removes the whole of the oil. If the object of the operation is to obtain the oil, and not the distilled water, the latter should be preserved, and used again and again with fresh herbs, because having in the first operation dissolved up as much oil as it is capable of doing, it causes no loss to the subsequent distillations.

It may, perhaps, be thought that our article is incomplete, from our not giving any particular directions as to the manufacture of spirits, both as regards the first fermentation and subsequent distillation; but our readers should bear in mind that the manufacture of spirit is illegal, and the result is most frequently a heavy fine and imprisonment, to which we have no wish that our articles should be introductory.

HOUSEHOLD RECEIPTS.—CLEANING, DYEING, RENOVATING, MENDING, PRESERVING, ETC.

BLACKING TO PRESERVE LEATHER.—Take spermaceti oil, four ounces; molasses, twelve ounces; mix. Add by degrees twelve ounces of ivory-black, mixing it in smoothly, and rubbing it well, so as to leave no lumps; then add gradually a quart of the best white-wine vinegar. If too thick, add more vinegar; stir it hard, and let it stand in the jar three days, stirring frequently with a round stick. Bottle it for use. If still too thick, even when warmed at the fire, dilute with a little more vinegar.—A. S.

BLACKING FOR DRESS BOOTS AND SHOES.—Gum arabic, eight ounces; treacle, two ounces; ink, half a pint; vinegar and spirit of wine, of each two ounces. Dissolve the gum and treacle in the ink and vinegar; then strain and add the spirit.

FRENCH POLISH FOR BOOTS, SHOES, AND HARNESS.—Take two pints of the best vinegar and one pint of soft water; stir into the mixture a quarter of a pound of glue broken fine, half a pound of logwood chips, a quarter of an ounce of finely powdered indigo, a quarter of an ounce of the best soft soap, and a quarter of an ounce of isinglass. Boil for ten minutes or longer; then strain the liquid, bottle, and cork. When cold it is fit for use. Remove the dirt from the boots, &c., with a sponge and water. Then lay on the polish with a clean sponge. Should it prove too thick, hold it near the fire to warm a little, and the heat will liquify it sufficiently.—J. M.

TO DETECT DAMPNESS IN BEDS.—First have the bed well warmed with a warming-pan; then, the moment the pan is taken out, introduce between the sheets an inverted glass tumbler. After it has remained there a few minutes, withdraw it. If the glass is found dry, you may go to bed without any apprehension of chill or rheumatism. If the glass is covered with drops of wet or damp steam, the safest plan is to take off the sheets and sleep between the blankets, as a second pair would probably be no better than the first.

EXPELLING INSECTS GENERALLY.—All insects dislike penny-royal; the odour of it destroys some and drives away others. At seasons when fresh green bunches of penny-royal are not to be obtained, get oil of penny-royal, pour some into a saucer, and steep in it small bits of wadding or raw cotton; lay them about in corners, closet-shelves, bureau-drawers, boxes, and all places where you have seen cockroaches or ants, or wherever they are likely to be found. If the insects do not speedily disappear, renew the cotton and penny-royal. It is also well to place some of them about the bedsteads, between the sacking and the mattress. Bunches of penny-royal are excellent for brushing off that very annoying little insect, the seed tick.—H. S. C.

TO DESTROY BED BUGS EFFECTUALLY.—Take two ounces of quicksilver, and the whites of two eggs, and so on in this ratio for a larger or smaller quantity. Beat the quicksilver and the whites together until they unite and become a froth. With a feather then apply the compound thus formed to the crevices and holes in your bedsteads. This done once or twice in a year will prove effectual.—J. M.

POISON FOR BUGS.—Spirits of wine and spirits of turpentine, of each four ounces; white mercury and camphor, of each half an ounce: mix. A chemist will make it up; and it must be applied with a brush to the bedstead or box infested by the insects.—J. D.

TO MAKE BOTTLES AIR-TIGHT.—This may be done without luting or grinding, and consists in only having a groove round the neck, into which the cap fits, so that the groove may be charged with water or mercury.

TO BOTTLE PORTER.—To four gallons of porter take three-quarters of a pound of coarse sugar, boil it in three quarts of water five minutes, when cool, add a tea-cup of fresh yeast. Let it work till it creams over, then put the porter to it, and bottle off.—Mrs. H.