A Treatise on Soap-Making/Treatise on hard and soft soap-making

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A Treatise on Soap-Making
by John Carmichael





ALTHOUGH it is not absolutely needful that soap-makers should know where, and how, their materials are originally produced; yet it is essentially so, that he be acquainted with what is more intimately connected with his own real interest; that is, how to detect frauds therein when made, and be enabled to judge of the strength, quality, and fitness of such materials for his purpose, when prepared and brought to market.

These necessary precautions known, will guard the manufacturer at all times against every imposition, whether attempted in quality or price.

To obtain a perfect knowledge, or as much information with regard to alkaline salts as possible, ought to be the principal study of the soap-boiler. The whole art of the trade, the sole prospect of aggrandisement, depends upon, and must accrue from such knowledge well digested.

As the making of soap is the avowed purpose of this Treatise to explain, the doing so, by barely exhibiting the method of treating the materials in a soap-work, preparatory for using; of charging, boiling, and finishing a pan of soap, only, would be doing nothing; would be communicating no more information than any laboring man, with a small degree of attention, in one of those works, may soon be master of. To complete the soap-maker, a far different, and more extensive degree of knowledge is necessary. An intimate acquaintance with the alkaline materials, and their consequents, the leys, ought to be attentively cultivated, so as to be rendered perfectly familiar; the nature, strength, quality, and fitness of such reduced to a demonstration, clear and simple. After these necessary acquirements are substantiated, soap-making, with the various phenomena incident thereto, will become exceedingly plain, easy, and comprehensive. We shall therefore commence this treatise, by giving a short explanation, by way of introduction, of the different alkalis, with their source of production; avoiding all extraneous or useless matter, that could only serve to swell the book, without communicating any thing of importance to the soap-boiler.

Alkalis are of two kinds, fixed and volatile. The fixed kind are subdivided into two, the vegetable, and mineral or fossile alkali. The vegetable is so called, because it is procured from the ashes of burnt vegetables; the fossile, because it is found native in some places of the earth, and is the basis of sea-salt, and, in other parts, is dug out of mines in vast quantities.

They are called fixed, because they endure a very intense degree of heat without being dissipated in vapour, so as even to form a part of the composition of glass.

The volatile alkali is generally obtained by distillation from animal substances. In its pure state, this alkali is perfectly invisible, but affects the sense of smelling to such a degree as not to be approached with safety.

The acids and alkalis are generally thought to be entirely opposite in their nature to one another.

Some, however, imagine them to be extremely similar, and to be as it were parts of one substance violently taken from each other. Certain it is, that, when separated, they appear as opposite to one another as heat from cold.

Their opposite action, indeed, very much resembles that of heat and cold, even when applied to the tongue; for the alkali has a hot, bitter, burning taste, while the acid, if not considerably concentrated, always gives a sensation of coldness. In their action, too, upon animal substances, the alkali dissolves, and reduces the part to a mucilage (or clammy, glutinous, ropy substance); while the acid, if not very much concentrated, tends to preserve it uncorrupted. If an alkaline salt, and moderately strong acid, in a liquid state, be mixed together, they will immediately unite; and, provided the alkali has not been deprived of its fixed air, their union will be attended with a very considerable effervescence, or seeming fermentation.

If the alkali has been deprived of air, no effervescence will ensue, but they will quietly mix together; but, if a due proportion of each has been added, the liquor will neither have the properties of an acid nor an alkali, but will be what is called neutral. The bringing the liquor into this state is called saturating the acid, or alkali, or, combining them to the point of saturation.

If the liquor, after such a saturation, be gently evaporated, a saline mass will be left, which is neither an acid nor an alkali, but a new compound, formed by the union of the two, and which is called a perfect neutral salt. The epithet perfect is given it, to make a distinction between the salts formed by the union of an acid and an alkali, and those formed by the union of acids with earthy or metallic substances; for these will likewise unite with acids: and some of the compounds will likewise crystallise into regular figures; but because of their weaker union with these substances, the salts resulting from combinations of this kind are called imperfect.

All acids, the volatile sulphurous one excepted, change the blue infusions of vegetables, such as violets, to a red; and alkalis, as well as some of the imperfect neutrals, change them to a green.

This is the nicest test of an acid or alkali abounding in any substance, and seems the most proper method of determining whether a solution, intended to be neutral, really is so or not.

The two great divisions of salts are, into acids and alkalis. The first of these are known by their peculiar taste, which are called acid or sour. They are not found in a solid form; neither are any of them, except the acids of vitriol, of tartar, of phosphorus, and of borax, capable of being reduced to solidity.

The others, when highly concentrated, that is, brought to the utmost degree of strength of which they are capable, always become an invisible vapour, permanently elastic, until it comes in contact with water, or some other substance with which they are capable of uniting.

For such acids the name of salts seem less proper, as we can scarcely say that a vapour which is already much more fluid than water can be dissolved in that element.

Both vegetable and mineral alkali appear to be composed of an exceedingly caustic salt, united with a certain quantity of fixed air. This may be increased so far as to make the vegetable alkali assume a crystalline form, and lose great part of its alkaline properties. But, as the adhesion of great part of this air is very slight, it easily separates with a gentle heat.

The only method of depriving it of its fixed air entirely, is by mixing an alkaline solution with quicklime.

The alkaline salts for the use of the soap-boiler, are produced from the following materials: The first of which to be noticed is that well-known article, the produce of our own sea-shores, &c. called kelp.

From the large quantity of alkali therein contained, it is very justly esteemed an excellent and useful material in hard soap-making. The best of this article is made from sea-ware, or weed, cut from the rocks of the shores at low water-mark, not under four or five years old, and distant from a communication with fresh-water rivers. All the sand ought carefully to be washed from the ware when cutting, and the remainder, if any, shaken off while drying.

Particular attention should be had that no sand be mixed in the kiln when burning. The pernicious effects of sand are twofold; first, robbing the purchaser, making him pay for sand instead of kelp; and, 2dly, what is still worse, kelp burnt with sand is converted into a kind of vitrified substance, and from which it is next to impossible for the soap-maker to extract the alkali.

Kelp is always esteemed the best which is hardest, finest grained, and free from sand or earth. Sea-ware is a most useful article otherwise, besides the making of soap: it is an excellent manure for land, for which purpose it is often applied in the maritime parts of Scotland and other countries.

In the island of Jura and Skye, it frequently serves as a winter food for cattle, which regularly come down to the shores at the recess of the tides to seek for it. In Gothland and Sweden also, the inhabitants boil it in water, and mixing therewith a little coarse meal, feed their hogs with it. And we are informed, that in Jura, and some other of the Hebrides, the inhabitants dry their cheeses without salt, by covering them with the ashes of this plant. These ashes abound with such quantity of salts, that from five ounces of them, may be procured two ounces and a half of fixed alkaline salt, that is, half of their whole weight.

But the most beneficial use which such sea-weed can be put to, in the way of œconomy, is in making kelp; a work much practised in the Western Isles, Orkney, Shetland, Norway, &c.

I shall next take notice of an article peculiarly adapted to white soap-making, although equally good for yellow. It is the produce of the kingdom of Spain, at least the best is from that country, and called


The description we meet with of this plant is as follows, viz.

Barilla or baritha, the name of a plant cultivated in Spain for its ashes, from which the purest kinds of alkali are obtained.

There are four plants which, in the early part of their growth, bear so strong a resemblance of each other, as would deceive any but the farmers and nice observers. These four are, barilla, gazul (or, as some call it, algazul), soza and salicornia, or salicor. They are all burnt to ashes, but applied to different uses, as being possessed of different qualities. Some of the roguish farmers mix more or less of the three last sort with the first; and it requires a complete knowledge of the colour, taste, and smell of the ashes, to be able to detect their knavery.

Barilla is sown fresh every year; its greatest height above ground is four inches; each root pushes out a vast number of little stalks, which again are subdivided into smaller sprigs, resembling samphire[1]; and altogether form a large, spreading, tufted bush. The colour is bright green. As the plant advances to maturity, this colour vanishes away, till it comes at last to be a dull green, tinged with brown.

Gazul bears the greatest affinity to barilla, both in quality and appearance. The principal difference consists in its growing on a still dryer, salter earth, consequently it is impregnated with a stronger salt. It does not rise above two inches out of the ground, spreading out into little tufts. Its sprigs are much flatter and more pulpy than those of barilla, and are still more like samphire. It is sown but once in three, four, or five years, according to the nature of the soil.

Soza, when of the same size, has the same appearance as gazul, but in time grows much larger, as its natural soil is a strong salt marsh, where it is to be found in large tufts of sprigs, treble the size of barilla, and of a bright green colour, which it retains to the last.

Salicor has a stalk of a deep green colour, inclining to red, which last becomes by degrees the colour of the whole plant. From the beginning it grows upright, and much resembling a bush of rosemary.

Its natural soil is on the declivity of hills, near the salt marshes, or on the edge of the small drains or channels made by the husbandmen for the purpose of watering the fields. Before it has acquired its full growth, it is very like the barilla of those in which the ground has been dunged before sowing. In these years of manuring, barilla, contrary to its usual nature, comes up with a tinge of red; and when burnt, falls far short of its wonted goodness, being bitter, more impregnated with salts than it should be, and raising a blister, if applied a few minutes to the tongue.

Barilla contains less salt than the others. When burnt, it runs into a mass resembling a spungy stone, with a faint cast of blue.

Gazul, after burning, comes as near barilla in its outward appearance, as it does when growing in its vegetable form; but, if broken, the inside is of a deeper and more glossy blue. Soza and Salicor are darker, and almost black within, of a heavier consistence, and very little or no sign of spunginess.

All these ashes contain a strong alkali, but barilla the best and purest, though not in the greatest quantity. Upon this principle, it is fittest for making glass, and bleaching linen. The others are used in making soap. Each of them would whiten linen, but all, except barilla, would burn it.

The method used in making barilla is the same as that followed in Britain in burning kelp.

The plant, as soon as ripe, is plucked up, and laid in heaps, then set on fire; the salt juices run out below into a hole made in the ground, where they collect into a vitrified lump, which is left about a fortnight to cool. An acre may give about a ton.


Is a fixed vegetable alkali, another valuable material in hard soap-making, prepared from the ashes of burnt wood in America, Russia, &c. The process of preparation is nearly as follows.

A quantity of wood being burnt to ashes, these, while hot, are raked together into a heap, in which state they remain for ten or twelve hours. The purpose of this is, to give the embers, or black bits of the wood, sufficient time to dissolve, and be thoroughly converted into a white ash. These white ashes are boiled with water, for the purpose of extracting the salt. This water being drawn off, is again boiled, and evaporated in a broad pan, over a strong fire, until the whole is reduced to a perfect dry salt.

In this state, the salt is thrown into a proper fluxing furnace, where they are converted by a strong heat into a red hot mass. This is drawn off by means of a hole in the side of the furnace, and received into iron, or other moulds, and left to cool. When cold, the lumps are broke up, and packed in close casks for exportation, being then completely ready for use. Most other ashes of the pot kind are prepared after a similar process; it is therefore unnecessary here to say more respecting them.

There is also a second and third sort made; but these are in general so full of refuse, especially the last, as to render them of little or no consequence to soap-makers.

Having mentioned a few of the principal, and certainly the best ashes used in the manufacturing of hard soap, we shall turn for a little our attention to the mode used for detecting sand therein.

This low, dirty, and abominable fraud, is but too frequently practised, not only by kelp-burners, but barilla-makers also; that is, mixing sand with their commodity while manufacturing, and in a liquid state.

The process I have used for detecting sand is simple, and not tedious, viz. take two ounces of a fair sample from any parcel meant to be purchased; beat it down in a mortar very small, pour some boiling water upon it, and rub it well in the mortar; pour off this, and add more, and so continue until all the black light substance is gone off with the water. The sand will then be found in the bottom of the mortar, and, if surveyed with a magnifier, will resemble in appearance small pebble stones, or channel, of various colours. Dry and weigh the sand; and from the quantity contained in the two ounces, a calculation may be made for the hundred weight or ton.

A certain given quantity of water ought always to be allotted for trying this expeririment; say, one or two pints; and by weighing one pint thereof afterwards, when the experiment is finished, the quantity of alkaline salt may also be discovered which one pint of said ley contains; thus, an English pint of spring water weighs 15 oz. 3 drs. 12 gr., so that all above that weight in the rubbing water, or ley, must be supposed alkaline salt. The price of the article ought to be regulated according as the experiment turns out.

From these ashes already mentioned, the strongest and purest vegetable alkali is obtained. From other vegetables, as fern, broom, bean-stalks, &c. an alkaline salt is produced, but so impure, and in such small quantities, that no soap-manufacturer in this country can use them, with any reasonable expectation of profit.

The other ashes (although sometimes used in hard soap-making, are more proper for bleaching linen, being preferred for their whitening quality, and mildness of the alkali) are the following:


These appear to be a pure alkaline salt, mixed with a small quantity of vitriolated tartar and earth. Half a pound of these will give about 5½ ounces of pure salt.


Are nearly of the same quality with the former, half a pound of them giving five ounces and seven drams of pure salt, with some vitriolated tartar and earth.


Have very much the appearance of slaked lime, and are, like it, friable, or may be powdered or crumbled betwixt the fingers. Half a pound of them will only give about ten drams and fifteen grains of a very caustic salt. These consist, therefore, of a small quantity of alkaline salt, united with a large quantity of lime.


Are of the colour of iron-stone, and extremely hard, with many shining particles of charcoal in them. They have a saline taste, with a considerable degree of pungency or prickling heat. Half a pound of these ashes being boiled in a quantity of water for twenty-four hours, and evaporated, produced only ten drams of a brown salt, having a strong caustic alkaline taste. Upon examination, they appear to contain an earth half vitrified, some lime, alkaline salt, and a quantity of sulphur.


Are of a paler colour than the former, with some small pieces of charcoal in their composition. Half a pound of them dissolved in water, filtrated and evaporated, yielded only eleven drams one scruple and two grains of alkaline residuum.

The blue and white pearl ashes, discovered by experiment to be pure alkaline salts, without any considerable mixture of heterogeneous bodies, may be used in hard soapmaking, mixed with kelp or barilla, with certain success. When used alone, a large quantity of common salt is necessary; nor is the soap ever so firm and hard as when they are combined with kelp, &c.; and soap made with these ashes alone, is always apt to get softer by age. Upon this account, pearl ashes seem much better calculated for soft, or green soap, than hard. A boil, however, with these pearl ashes, after the rosin have been melted, is peculiarly serviceable for killing the tallow, (according to the common phrase); it converts the whole mass in the pan to a consistence, or thin weak soap. But this will be better understood when we come to the operation of boiling or making the soap; a process which we shall immediately set about.

Let us now suppose that every thing is ready for commencing the operation upon a moderate scale, viz. that there is a small soap-pan, capable of casting from 20 to 24 cwt. of soap, six or eight iron vats, or caves, with receivers that will contain 12 or 14 cwt. of kelp or ashes, each; that there is also kelp, ashes, tallow, lime-shells, and palm oil at hand. These are all the materials necessary for performing the operation, and finishing a pan, or making of hard soap.

The first thing to be done is, to prepare for setting a cave, viz. Break down very small about 12 cwt. of kelp, and, to make a good ley, 2 or 3 cwt. of American pot-ash may also be broke and mixed therewith. Barilla ash is generally set by itself alone. The breaking, however, of the American pot-ash, from the danger of sparks (if great care is not taken) of flying into the eyes, or lodging about the feet, &c. would be as well altered to melting down, or dissolving in boiling water, and then poured upon the other materials (just now to be mentioned), after they are put into the cave.

The kelp now broke, spread about one-sixth part of it upon the floor, or slake-pit, if there is one, upon which lay about half a bushel lime-shells, and water them. When the shells begin to burst and crack, put on another layer of kelp, then more shells, and water them; and so on, stratum super stratum, or one above the other, until there is about the quantity of 2½ or 3 American ash barrels of shells mixed with the 12 cwt. of kelp. Let this stand for the space of two hours. The cave in the interim may be got ready for receiving them, thus: Lay two rows of bricks upon the bottom, from the hole or pipe quite across to the opposite side, forming therewith a small channel, of three or four inches breadth. Cover this over with any convenient thing, such as slate, tyle, a piece of dale, &c. And to crown the whole, lay on some straw, or an old bass mat, &c. This is to prevent the grosser parts of the materials from getting in and stopping up the channel, intended only for the leys to run in. Stop up the pipe, or hole in the cave, with a pin, about which ought to be lapt a piece of paper to keep all close.

These preparations now accomplished, we proceed to what is generally termed,


The principal object here to be observed, is to mix the compound well together, previous to putting into the cave. The first backet or two should be very gently laid upon the covered drain, or bottom of the cave. This will secure the straw, or mat, from being disturbed afterwards, by throwing in the rest of the materials.

Throw on two or three pales of water, at different periods, during the setting, which will have the effect to dissolve any small particles of the shells that may formerly have escaped the water. Observe always to leave a vacancy at the top of the cave, of about eight or ten inches at least, in order to give room for swelling of the lime, and filling up with water.

Supposing now the kelp and lime all put into the cave, and no American ash therewith, but that these ashes have been melted down, or dissolved in boiling water, and are converted into a ley; pour that upon the top of the other materials just put into the cave, and fill up with water until the whole is completely saturated therewith; the completion of which will be evident, when the bubbling in the cave ceases to arise. Let the whole now stand for 12 or 14 hours, adding, however, a little more water as the stuff appears to dry up, or absorb that already put on. When the cave has stood the above time, loose the pin, and let the ley run briskly off. When all is off, stop up again, and fill with water, which may stand the half of the former time; the pin may again be loosed, and the leys allowed to run gently off, keeping the cave always filled up or supplied with water. It may be unnecessary here to remark, that we must hitherto be supposed as laying down directions to a person just going to commence soap-making, but perfectly ignorant of the operation, and that he is preparing every necessary agreeable thereto. In that case, descending to particulars will, I hope, be excused by the knowing, or more experienced reader.

We shall now go on by informing, that before beginning to boil, more leys must be got ready; consequently, another cave may be prepared in the same manner as the former one; with this exception only, that, instead of filling up, or supplying the second cave with pure water, let it be run through the former cave first, and then put upon the second. The intention of this is obvious; that, while the last is supplied with water, the remaining strength of the first is extracted, and collected into the second; and this must be the uniform practice at all times, that none of the alkali be lost; never turning out a cave, as spent, until you discover by the test the alkali is vanished.

Having just mentioned the test, I shall take this opportunity of explaining what it is.

The test is a thing so necessary for a soap-boiler, that it is impossible for him to conduct his operations with propriety without it; yet, I believe, there are hundreds in the trade that know nothing at all about it: be that as it will, I say, they ought to know it; nor can any man discover when a soap-ley is totally deprived of its alkali, without its assistance.

It is prepared in the following manner: Take a parcel of the blue flowers of any vegetable, violets, for instance, or the blossom of the mallow; beat them with the edge of a knife, and squeeze the juice of it into a tea-cup; with a small brush, or hair pencil, lay over a sheet of white paper with this juice, and when dry it is fit for use. All alkalis will turn it green, and all acids will turn it of a red colour. A combination of them both to the point of saturation, will not in the smallest degree alter the colour of the test, because they are then said to be neutral, having neither the properties of an acid, or an alkali; but add a few drops more, of either the one or the other, the effect will be evident. If alkali is added, the test will be green; if acid, it will be red.

An intimate acquaintance with every particular relative to the leys, is the one thing needful for a soap-boiler, being as it were the ground-work of the whole operation, and materially essential to be well understood, before any attempt ought to be made at soap-making.

We come now, of course, to examine the leys already prepared, and to determine by experiment whether they are, or are not, fit for soap-making; that is, whether they are caustic and fit, or in a mild state, consequently unfit for the purpose.

Unless a soap-ley be rendered caustic, or deprived of its fixed air, it can have no natural attraction for vegetable or animal subtsances, such as oil, tallow, or grease of any kind, so as to convert them into a soap. For the sole purpose, therefore, of extracting the fixed air from the leys, do soapmakers use quicklime. Depriving the mild alkali of its fixed air, renders it caustic, or of a burning, corroding quality, and of that peculiar nature that instantly attach themselves to all greasy substances, and converts them into soap.

The common vulgar notion, of using quicklime for its heat, is a mistaken idea, although I know it to be entertained by many soap-makers. Our most celebrated professors of chemistry[2], when preparing a soap-ley, generally slake and sift their lime; consequently, banish entirely all regard for heat in the lime; using warm water rather.

A mild ley, or that possessing fixed air, can have no effect upon vegetable or animal substances, so as to convert them into a soap.

Hence we may perceive the pernicious practices of some soap-boilers, (or pretenders to be so), namely, melting down, or dissolving American ash in boiling water, and, in that mild and improper state, adding those leys to the boiler.

Such consummate ignorance persevered in, must, and always have proved ultimate ruin to the person himself, or his unfortunate employer.

To determine, therefore, the proper state of the ley, take a quantity in a glass, or teacup, drop therein a few drops of vitriolic acid, or oil of vitriol; if this causes an effervescence, or seeming fermentation in the ley, the fixed air is not fully extracted; but, if no such appearance ensue upon the combination of the acid and alkali, the ley is fit for immediate use, being arrived at the state of a proper caustic soap-ley.

A soap-ley, by being long exposed in open vessels, will lose the whole of its causticity, and seem entirely restored to the state of an ordinary fixed alkali. The keeping them as close as possible, therefore, appears exceedingly necessary.

By means of the acid may be discovered also the comparative strength between one ley and another, and so ascertain which of the two contains the greatest quantity of fixed alkaline salt. Thus, take a specific quantity of each; a wine glassful, for instance; drop therein a dozen drops, or so, of acid; stir with a bit stick, and apply a slip of the test-paper. If it appear green, more acid must be added, and stirred again. Applying the test a second time, if still green, a few more drops must be added; and so continue, until you find the paper is by no means altered in the colour, neither green nor red. The ley is then neither an acid nor an alkali, but neutral, or a combination of both, brought to the point of saturation. A few drops more of the acid, would occasion the test-paper to take a red, instead of a green colour, which would distinctly show the power of the acid to prevail.

Treating in this manner the different leys, then counting the number of drops taken to neutralize them, the strongest ley will be discovered to be that which have required the greatest quantity of acid, to overcome the power of the alkali.

Soap-leys are also judged of by their specific gravity, or weight, comparative to water.

  oz. dr. gr.
An English pint of spring water weighs about 15 3 12
A strong soap-ley, the English pint, weighs about 17 6 24
The difference between the two is, 2 3 12

—and supposed to be the quantity of fixed alkaline salt contained in one pint of such ley. A most accurate and easy method for ascertaining the strength of soap-leys for immediate use, is as follows, viz.

Take a small bottle, and having filled it with water, put it into one scale, and as many small lead-shot into the other will exactly balance it. Suppose 12S is requisite for that purpose. Suppose, again, that the bottle and water just weighs 4 ounces; this is throwing it into 128 parts; half of that is 64/128, or 2 ounces; half it again, is 32/128 parts, or 1 ounce; again, is 16/128 parts, or 8 drams; then into 8/128 parts, or 4 drams; 4/128 parts, or 2 drams; 2/128 parts, or 1 dram; and 1/128 part, or half a dram, which is bringing it to the lowest denomination.

Get proper weights made for each of these divisions; and when the strength of the ley at any time is required to be ascertained, fill the bottle, and put it into the scale: into the opposite one, the balance of water, or the 128 shot, is placed; and as ley is always heavier than water, some one or other of the divisions will be wanted to balance the ley: therefore, whatever division may answer for that purpose, must be called the weight of the leys; the surplus weight above that of water being only reckoned, and not the whole quantity: For instance, if the bottle of ley take the division weight No 16, in that case the ley is 16/128 parts heavier than water, or 8 drams, reasonably supposed to be alkaline salt.

Notwithstanding that various sorts of alkali are enumerated, it is supposed that there is but one alkaline principle in nature, which, by being variously combined with sundry substances, assumes various particular properties. However, an alkali is never found pure in nature, but it is always combined with other substances, from which it must be separated by art, in order to obtain it sufficiently pure. The fixed alkali is obtained either from sea-salt, or from vegetables; hence it is called fixed mineral alkali in the first case, and fixed vegetable alkali in the second.

Having in the foregoing pages endeavoured to furnish the attentive reader with a tolerable idea of the preliminaries of soap-making, we shall now proceed to what I consider the easiest and most simple part of the business, the boiling; although by the ignorant and unwary conceived to be the principal requisite, and containing the whole mystery of the trade. As a proof of which, I take the liberty to mention, that it is within the compass of my knowledge, of several instances having occurred, where common excisemen, from their mere observations taken while attending, in the line of their duty, upon a soapwork, have had the daring presumption to pretend a complete knowledge of soap-making; in consequence of which, have had the address to induce several individuals of fortune to risk their money in an unknown and dangerous undertaking, confidently relying upon the false skill of those self-taught gaugers as conductors and managers.

A short time, however, was always sufficient to convince, by woeful experience, such unfortunate gentlemen of their own error and their managers ignorance.

The leys being now ready, we shall commence with a boiling of brown or yellow soap. For this purpose, let there be weighed 10 cwt. of tallow, and about 3 cwt. of rosin; the rosin to be broke in small lumps. In the first place, put into the boiler about 150 or 200 gallons of leys (about the weight of 16 oz. 4 dr. 48 gr. the English pint, which will nearly answer to No 32 of the forementioned divisions), and set the fire; then add the tallow and rosin. This done, the pan is said to be charged.

A good fire may be kept up until all is thoroughly melted, and the pan brought to boil; during which time there ought to be constant stirring with the peddle, to prevent the rosin settling to the bottom. If the goods or materials in the pan appear to swell up, damp the fire, which is done by opening the furnace door, and throwing ashes thereon (some have proper dampers), when the whole will boil at leisure. As the caustic alkali immediately grips to the tallow, there is no occasion for long boiling; about two or three hours wall be long enough: the fire may then be drawn, and the pan allowed to stand for four or six hours, when the weak leys may be pumped off, and fresh ones added for second boil. It may be necessary to mention, that when the pan is wished to be cranned, or pumped off sooner, a few pails of cold ley must be thrown in, a little after the fire is drawn.

Set the fire again for second boil, and when properly a-boil, two or three hours may be sufficient at any one time to continue the boil: the strength of the leys are often gone before that period arrives. A short experience, however, with attention, will perfectly inform any sagacious person with regard to this particular.

The boilings to be thus continued day after day, until the soap becomes thick, and of a strong consistence. Take then a little upon the forefinger, and after letting it cool a few seconds, press it with the thumb. If it squeezes into a thin, hard scale, the soap is fit, or ready, for finishing: if otherwise it appear greasy, and stick to the finger, and of a soft consistence, more leys must be added, and if that does not harden it, another boil must be given. But, in consequence of the former scaly-like appearance, give the pan a good hearty boil, and draw the fire. Cool down with two or three pails of leys, and in about two hours thereafter pump off the leys; which should be done at all times as clean as possible. This done, put in six or eight pails of water to the boiler (no leys at finishing being used), set a brisk fire, and keep constantly stirring with hand-stirrer and paddle alternately, until all is melted, and begin to shew an appearance something like thin honey. Take now a little from a boiling part, upon the hand-board, and observe, when held up, if any leys run clearly from it: if they do, more water must be put in, and the boil continued. When, upon the other hand, no leys run from the soap when held up slanting-ways upon the board; in that case, too much water have already been given. A little strong salt ley must now be added to open it, technically termed cutting up; or, instead of salt ley, a little strong common salt and water; about half a pailful may do. I should prefer this last to the ley, wishing now to exclude as much as possible all alkali from entering the pan. We come now to the most critical part of boiling, that is, the grand criterion observed in finishing soap: and it ought to be particularly attended to, that the soap be brought to that state, so as, when held up upon the hand-board, the leys do not run down from the soap, but are seen, as it were, just starting from it. The fire may then be drawn away, and the soap declared finished: or, if palm-oil is wished for making it of a beautiful colour, about 20 lib. may be put into the boiler, after you discover, as above, the soap to be finished; and in about half an hour after the oil is put in, the fire may be drawn, and the whole allowed to stand for 48 hours, when it may b cast into the frames.

In about three days (supposing the frames 30 inches deep), the whole will cut up into bars.

A Charge for pure White Soap.

The boiler being made perfectly clean, put in 10 cwt. of best home melted tallow (no rosin is used in white soap), with 200 gallons leys, No 22; melt down with a moderate fire, as the goods now in hand are something similar to milk, exceeding apt to boil over.

Close attention, therefore, is absolutely needful upon this first boil; which may be continued about two hours, with a moderate fire, when it may be drawn away, and the pan allowed to settle about two hours, when the leys may be drawn off. The process to be observed in this soap is exactly similar to the last operation. Two or three boils a-day to white soap may be given with great ease; the leys sooner subsiding in the boiler than with yellow soap, and can be cleaner pumped off.

When sufficient boils have been given, and the soap arrived at perfection, it will assume an appearance something like a curdy mass. Take then a little upon your forefinger, (as before directed); and if the same effect seems to attend it, that is, when pressed with the thumb it squeezes into a thin, hard, clear scale, and parts freely with the finger, the soap is ready for finishings Draw the fire cool down with a few pails of ley, and in a short time thereafter pump clean off.

Set the fire, and add to the soap eight or ten pails of water, (the pail I suppose to contain about nine or ten English gallons). When this is melted, and properly incorporated with the soap, try, as formerly directed, if the leys run from it when held up upon the hand-board. If they do, more water must be put in. If they do not run, or any appearance of them, continue boiling for a short while longer, and then add a pail of salt and water pretty strong, mixed together; about one-third salt, and two-thirds water. This will have the effect to cut up the pan, or separate the soap and water completely from one another. When this is apparent, draw the fire; let it stand for half an hour, when the water will pump off, bringing therewith most of the remaining alkaline leys of the former boil.

This I call the first washing; and if kelp-ley has been used in the operation, the propriety of this must be conspicuous, for the water pumped off will be of an exceeding dark bottle green colour. The finishing of white soap without this precaution, is the sole cause of that blueness so frequently observed in that article when made and brought to market.

The blue ley being pumped clean off, set again the fire, and put into the boiler six or eight pails of water; and when thoroughly incorporated and boiled some time, try if the water runs from the soap: if it does, add water in small quantities at a time, until it is observed not to run, but, as formerly mentioned for yellow soap, to appear as just starting from the soap; in that case, after giving a good boil, and swelling the soap up in the pan to near the brim, draw away all the fire, and spread it about to die away. The pan is now finished, and may stand about twelve or fourteen hours; and if the quantity is large, that is, two, three, or four ton, double this time to stand will be much in favour of the soap, providing always that it can be kept very close and warm in the boiler. If any blueness still appear, repeat the washing.

Before casting, I would recommend the frames to have a bottom and lining of coarse cloth, for white soap only. After all is cast into the frames, let it be well stirred, or crutched; and it is very proper that it also be covered close up with old sheets, bass mats, &c. upon the top of the frame and soap, and allowed to cool gradually, and all together.

In about three or four days (supposing, as formerly, the dip 30 inches), the coverings and frames may be taken off, and the whole cut up into such size of bars as may best suit the customers.

Having in the foregoing pages endeavoured to give a clear and distinct illustration of the proceedings necessarily attending the manufacturing of yellow and white soap, I have only to add, that frequent trials, and diligent observation, can alone direct to further improvement.

We come next to explain how this white soap, at a moderate expence, may be perfumed or scented, in order to make it appear in the character of what is generally denominated Windsor Soap.

This perfume must be prepared by the manufacturer himself; for to purchase it from perfumers would be attended with too enormous an expence. I have acquired this perfume in the following manner, viz. Procure a small still, about 20 English gallons, with a proportionate worm of six or eight turns, the placing of which properly any mason can instruct. Put into the still about 14 or 16 libs, of good fresh caraway seeds, and fill up with water about two-thirds full: let the head and body of the still be luted together, as also the pipe where it enters the worm. Set a pretty brisk fire, and as the still boils, the essential oil will run off, which may be received into bottles, having a filler in the mouth. When all the oil seems to appearance to be extracted, the operation is finished, and nothing remains but to separate the oil from the water that has accompanied it. This must be accomplished by a separating-glass, or, if that cannot be had, prepare a few worsted threads; put one end of them into the bottle having the essential oil and water in it, and the other ends into an empty bottle along side: by this means, the whole of the essential oil will make its escape from the bottle of oil and water, by ascending the worsted threads, and drop into the empty bottle.

The oil being prepared and collected, we now proceed to get it ready for introducing into the soap. In its present state it is not fit, but must be, according to the common term, killed, or deprived of its oily nature. This is accomplished by mixing it with a small quantity of spirit of wine, or alcohol stirring them together until the oil is observed to lose its oily quality, and to become, as it were, one body with the mixing spirit. The proper time for incorporating this perfume with the soap, is during the casting into the frames, and should be put in at two or three different periods. When all is in, finish as formerly directed, by stirring and covering close up.

This essential oil of caraway is esteemed an exceeding strong perfume, asserted by some chemists to be about twenty times stronger than anise seed. As a proof of the amazing volatility of this perfume, the distiller will find some difliculty, for several days after the operation, to wash himself clear of the scent, even suppose he strip to the skin, and change every article of dress. The quantity, therefore, to be used by the soap-maker, for his certain purpose, must be left to his own experience and discretion, to correspond with the quantity of soap intended to be perfumed.

Having in the preceding pages exhibited a clear and comprehensive view of the whole proceedings attending the charging, boiling, and finishing of yellow, white, and perfumed, soap, I shall endeavour, in the next place, to present the reader with an account of the making of a different quality of soap, and shew, by a few specimens from real operations, the method, materials, and proportions, used in the manufacturing of black, green, or soft, soap.

The peculiar method pursued in making this soap, differs considerably from that of hard soap. The hard has the whole leys extracted totally before finishing: Soft soap, on the contrary, retains the whole leys used in the making thereof; becoming, with the other materials employed, one compound body, called, soft soap. A few examples will clearly explain the nature and practical means made use of in producing this very useful soap.

The fundamental principle upon which the proper management, or manufacturing, of soft soap depends, as we have before stated for hard soap, is a certain knowledge of the quality and strength of the leys; for however necessary that knowledge may be in hard soap-making, it is peculiarly more so in soft.

The using of leys below the proper strength alloted, will materially spoil the whole boiling, and occasion much additional trouble to the manufacturer, with a considerable loss of time, before a proper arrangement afterwards can be eftected, and things again put to rights. To avoid any inconveniencies of that nature, the workman must be very particular in ascertaining the exact strength of his boiling ley. When English ashes are used, the strength of a boiling ley (according to the former calculation), is, 18/128; when foreign ashes, 22/128 parts, or, as they are commonly designed, carats. We shall here set down the former calculation of the different degrees of strength of the leys, for the greater convenience of the operator, in the form of a table.

128 parts, or 4 ounces.
64/128 ditto or- 2 ounces— 1st division.
32/128 ditto or- 1 ounce— 2d division.
16/128 ditto or- 8 drams— 3d division,
8/128 ditto or- 4 drams— 4th division.
4/128 ditto or- 2 drams— 5th division.
2/128 ditto or- 1 dram— 6th division,
1/128 ditto or- half a dram— 7th division.

After the proper weights for each of the divisions are got ready, it will be easy to pick out such as may serve for the weight of any ley: For instance, No 16 and No 2, is 18 carats; or, 16, 4, and 2, is 22 carats; the boiling ley for English and foreign ashes.

The weights and measures which I have had occasion to mention, in the course of the preceding pages, are those used in the dispensaries, viz.

Wine Measure.

A gallon contains Eight pints.
The pint Sixteen ounces.
The ounce Eight drams.
The pound contains Twelve ounces.
The ounce Eight drams.
The dram Three scruples.
The scruple Twenty grains.

  oz. dr. gr.
The weight of an English pint measure of strong soap-ley is, 17 6 24
Distilled water, 15 1 50
Rain water, 15 2 40
Spring ditto, 15 3 12
Sea ditto, 15 5 20
Oil of vitriol, 28 5 20
A good boiling ley, 16 4 48

Soap Frame, 45 Inches long, by 15 Inches broad, Inside.

DIP. HOT AREA, 24.10. DIP. COLD AREA, 24.87.
Inch L. s. d. qrs. pts. Inch L. s. d. qrs. pts.
1 0 4 0 3 .21 1 0 4 2 1 .447
2 0 8 1 2 .42 2 0 8 4 2 .894
3 0 12 2 1 .63 3 0 12 7 0 .341
4 0 16 3 0 .84 4 0 16 9 1 .788
5 1 0 4 0 .05 5 1 0 11 3 .235
6 1 4 4 3 .26 6 1 5 2 0 .682
7 1 8 5 2 .47 7 1 9 4 2 .129
8 1 12 6 1 .68 8 1 13 6 3 .576
9 1 16 7 0 .89 9 1 17 9 1 .023
10 2 0 8 0 .10 10 2 1 11 2. .470
20 4 1 4 0 .20 20 4 3 11 0 .940
30 6 2 0 0 .30 30 6 5 10 3 .410
40 8 2 8 0 .40 40 8 7 10 1 .880
50 10 3 4 0 .50 50 10 9 10 0 .350
100 20 6 8 1 .00 100 20 19 8 0 .700


Suppose 5 inches dip, by hot area.
24.1 area.
5 inches.
Discount one-tenth 120.5
108.45 neat libs. wt.
Duty - 2.25 or 2¼d. per lib.
s. d.——
20 4.05,00 , or,
L. 1 : 0 : 4 : 0.05. See Table.


Suppose 5 inches dip, by cold area.

24.87 area.
5 inches.
Discount one-tenth 12435
111.915 neat libs. wt.
Duty - 2.25 or 2¼d. per lib.
20 11 3.23500 , or,
L. 1 : 0 : 11 : 3.235. See Table.
In casting the dip of a soap frame, both areas are used by the Exciseman. For instance, suppose 5 inches of warm soap be allowed to cool in the frame, it may be discovered to have decreased 3, 4, or 5-10ths; consequently, the soap must be cast up by the hot area for the five inches of original dip, and by the cold area for the real dip after cooling, say 4 inches 7-10ths, or 4, 6, or 4, 5, &c.; and whichever of these dips turn out highest, the trader is charged with for duty.

It might be equally correct, and full more convenient and expeditious, to use, for the weighing, or ascertaining the strength of the leys, a glass hydrometer, marked inside of the tube with figures. These can be had from any weatherglass-maker. This hydrometer may easily be adjusted to all the divisions in the foregoing table, as also to rain, river, and distilled water, sea water, &c.

To use the above hydrometer, a glass or crystal cylender will be wanted, the depth of which ought to be fully the length of the hydrometer, and of a diameter sufficiently large to admit the same freely.

When the leys are to be tried, fill the cylender, and introduce therein the hydrometer: it will then be seen which division, or number, the hydrometer sinks to; consequently must exactly ascertain, without farther trouble, the strength of such leys.

A proper boiling ley for soft soap, ought to weigh about 10 or 11 drams, which makes a very good medium. Seven pounds ten ounces tallow, avoirdupois weight, is supposed equal to a wine gallon nearly; and pump water, the English gallon, should weigh about 8 lib. 2 oz. 10 dr. avoirdupois weight.

Upon these principles, we establish the proper standard weight for English leys to be (agreeable to the Table), 18/128 parts, or, as they are generally termed, carats, and for foreign ashes' lees, 22/128, or 22 carats. We shall now commence an operation with a charge for what is called


The quantity of leys requisite for completion of this charge, will be about 400 gallons, the weight of which to be about 11½ drams; about one-third of which must be put into the boiler previous to any of the other materials: afterwards add, 2 cwt. 2 qrs. tallow, 2 cwt. 2 qrs. hogs-lard, and 70 gallons olive oil. The leys herein to be used, are supposed to be from Hungarian and English (Essex) ashes. The proportion is, one of the English to eight of the Hungarian. The particular mode of proceeding is thus: After the leys are put in, add the tallow, and light the fire. When all the tallow is melted, put in the oil, and draw the fire a little afterwards, and allow the pan to stand about two hours. Light again the fire, and add about 20 gallons more of the leys. After the pan begins to boil, add now and then a little more leys, to the purpose of preventing the soap from boiling over: and this adding of lees to be continued until the soap is supposed to be about half boiled; when it will be time to try, whether the soap has got too much, or too little leys.

This trial is called proving, and is necessary to be done several times during the operation, and previous to the finishing. The method of performing it is this: Provide a piece of glazed Dutch delft, and also a clear clean knife: with the knife take up a piece of the soap from the pan, and if it turn whitish thereon, and falls from it in short pieces upon the delft, it is then concluded too much leys have been put in; to rectify which, a little more oil must be added. On the contrary, if the soap wants leys, it will fall from the knife in long, ropy-like pieces; in consequence whereof, add some more ley. When, however, it happens to be brought to perfection, neither wanting more leys nor oil, but just in a right state: it will then be observed, that when taken upon the knife, to stand the proper colour, not ropy, nor too white, but transparent. The fire may now be drawn, the soap being properly finished, and ought immediately to be cast into the barrels, firkins, &c.

Remember always, that after the second time the fire is lighted, to keep the soap boiling briskly, till the pan is nearly ready, when it ought to boil slow, until finishing, and ready to cast.

We have now gone through, and finished, the first pan. The second shall be an actual operation, noting the time spent thereon, and quantity of soap produced.


The materials to be used for this purpose are the following:

224 libs. tallow,
166 libs. hogs-lard,
55 gallons rape-seed, or olive oil,
180 gallons leys, weight 11½ drams, from pearl ashes.

The Process. In the first place, put into the boiler 140 gallons of leys, with the tallow; set the fire, and when the tallow is all melted, put in the oil, and draw the fire. Let all stand for two hours, when the fire may again be lighted, and immediately 20 gallons of leys put in: the other 20 gallons was added at different times, as before directed, in the course of the boiling. This boiling commenced at M. past 8, and was finished at E. past 7, and produced 33 firkins of good soap.


280 libs. tallow,
140 gallons leys, weight 11½ drams,
82 gallons whale oil.

Put in 100 gallons of leys, with the tallow, and light the fire. When the tallow is melted, add the oil, and draw the fire. Let all stand for two hours. Again light the fire, and add 20 gallons of leys. With this the boiling is continued until the soap is about half finished, when 10 gallons more leys is added. During the remainder of the boiling, add, at different periods, the other 10 gallons leys, which will completely finish the soap.

with Old Soap returned.

254 lib. tallow,
85 gallons train oil,
200 gallons leys, weight 11 drams, blue pearl ashes.

At M. 6, charged with 140 gallons leys, and all the tallow, with 239 lib. of old soap. Set the fire. At 8, the oil put in, and fire drawn. At 10, the fire again lighted, and 40 gallons of leys added. From this time till E. 2, at different times, add about 15 gallons leys. From this to 5, add at different periods, 5 gallons. At 6, the fire may be drawn, and shortly thereafter the soap may be cast into the firkins.

From these examples, founded upon real operations, the making of soap may be performed by any person, although never before acquainted with the business; at the same time it may be proper to inform such, of the necessity there is, on their part, of strict attention during the operation: the person ought continually to be poring into

  1. Samphire, or St Peter's Herb, a plant which generally grows upon rocky cliffs in the sea. It is usually pickled, and eaten for a dainty dish.
  2. See Dissertation on Spoiled Hard Soap, Appendix.