BIRMINGHAM and the surrounding districts obtain their chief supply of hard soap from the local manufactories, also from London, Liverpool, Warrington, and Bristol. Formerly soap making was carried on in most of the small towns of the kingdom, and but little was furnished by the seaport towns.
The improvements, however, introduced in the processes of manufacture by the larger makers in the seaport towns, together with the facilities of transit by means of canals and railways, have greatly diminished the number of makers in the interior parts of the country. About the commencement of the present century [19thC], the principal hard soaps in use were — white soap, consisting of soda and tallow; mottled soap, consisting of soda, tallow, and kitchen grease; and brown soap, consisting of soda, palm oil, and resin. The palm oil in its natural state being of a red colour, against which much prejudice existed, it was partially bleached by means of nitric acid. An improved method of bleaching was discovered by Mr. Boyle, who first introduced it at the works of Messrs. Blair, of Tipton. It consisted of simply heating the oil to a temperature of 430 degrees [Fahrenheit]. This improvement was in its turn superseded by boiling by steam and exposing a large surface of the oil to the action of the air. Finally, a still more effectual method of bleaching was discovered, and is now generally adopted. It is accomplished by treating the oil with bichromate of potash and hydrochloric acid. The superior quality soap yielded by this process greatly diminished the consumption of those kinds previously in use, and it became the staple article of demand in the Northern and Midland Counties. In London this kind of soap was objected to from its peculiar odour, and one made of tallow and resin was generally preferred. Since the repeal of the duty on soap, which occasioned a reduction to the consumer of more than 1½d. per lb., the tallow and resin soaps just referred to have had a largely increased consumption. About sixteen varieties are now manufactured, a blue mottled soap, made of palm oil and cocoa-nut oil, lately introduced, being much in request in this district. From time to time considerable improvements in the process of soap making have taken place, one of the most important of which was introduced about twenty years ago, being the application of steam to the boiling of soap, in lieu of the old method of boiling by an open fire. Another improvement consisted of an alteration in the mode of causticising the alkali. This is now done by boiling by steam a mixture of lime and carbonate of sodium. Previously the alkali was interstratified with lime in a vat, and the caustic soda separated by filtration.
A considerable saving has been effected in the cost of the production of the alkali used in soap making, by a process introduced by Mr. Gossage, of Widness (sic). The crude soda liquor obtained from the decomposed sulphate of sodium contained a portion of sulphide of sodium, which was objectionable on account of its communicating a blueish tint to the saponified fat. This defect, formerly obviated by evaporating the liquors and heating the residue in a reverberatory furnace, is now remedied by warming the liquors and passing them down through a tower filled with coke, through which a current of air is passing in an opposite direction.
Mr. Gossage also uses the weak caustic lees in his steam boilers instead of water, thus effecting by one process the generation of steam and the concentration of the lees.
With respect to the consumption of hard soap in Great Britain and Ireland, it is computed to amount to rather more than 100,000 tons per annum. Estimating the population at 30,000,000, this would give seven and a half pounds for each person.
The quantity produced in Birmingham and its immediate neighbourhood probably does not exceed 2,500 tons per annum.
Hard soap is made by boiling oil and tallow, or these materials mixed with resin, with a solution of caustic soda. To prepare this solution, which is called lees, a quantity of carbonate of sodium is first dissolved in a vat with boiling water, the solution is then syphoned off into another vat of large dimensions, where it is mixed with caustic lime, and the density reduced by water to twenty degrees of Twaddell's hydrometer. This reduction of density is found greatly to facilitate the causticisation of the lees. The mixture is boiled by free steam for an hour or more, and when the solution is, by testing, to be sufficiently caustic, the boiling is discontinued, the lime deposits itself in the vat, and the clear lee is removed by a pump into a reservoir. It will be found when cold to have a density of 24 degrees, and to contain about 7.85 per cent of caustic soda. The pans or "coppers" in which soap is made are large cylinders of wrought iron, from 15 to 20 feet in diameter, and from 12 to 15 feet in depth. The bottom is formed by a wide flange, in the centre of which there is a cup, 3 feet in diameter, and 2½ feet in depth, to receive the pump and a coil of pipes for boiling the copper by steam. This coil has no perforations, and is intended to heat the lee, or soap, by surface action only. Another coil of pipes with perforations, is laid upon the flange for the purpose of boiling by free steam.
The process of soap boiling is commenced by placing in the copper from twelve to fifteen tons of tallow, and adding a quantity of lee from the reservoir. The free steam is then admitted, and the materials brought into a state of ebullition. When it is found by tasting that the lee has lost its sharpness, another addition of lee is made, and this operation is repeated till the copper is full. The soda of the lee is now combined with the tallow, the product being in a state of close union with the water. To separate the latter, a quantity of common salt is added, which causes the partially saponified tallow to rise to the surface. The spent lee, which contains the glycerine previously in combination with the tallow, together with the common salt, carbonate and sulphate of sodium, and some other impurities, is now removed. This is usually done by a pump, though this method is troublesome and unnecessary. By the ninth section of the Act of Parliament which regulated the process of soap making till a late period, it was forbidden to remove the lees or soap from the copper by any other means than by a "moveable pump and open shute, or by pails and ladles only." It is difficult for anyone unacquainted with the trade to estimate the amount of inconvenience occasioned by such a regulation, and several makers finding it impossible to adapt the apparatus in use during the existence of the excise restrictions to modern improvements have recently erected new manufactories. The coppers were formerly placed in the basement of the building, and the soap had to be carried in pails to a room on the same or higher level. By reversing this order, and placing the coppers in the upper story, it is easy to remove either the lees or soap by running it off through a tap.
After the removal of the spent lee, a further quantity of lee is added, and the process above described is repeated till the whole of the tallow is converted into soap. This is known to be accomplished when after a long boiling the causticity of the lee is maintained, and the soap is no longer greasy to the touch, but breaks into scales or layers when pressed between the fingers. The partially spent lee is now removed, and such a quantity of water added as will bring the soap into a perfectly fluid state. When this is found to be effected, lee is slowly added till the soap begins to part from the weak lee. The use of free steam which has been hitherto employed is discontinued, and the copper is made to boil by the close coil. As the evaporation proceeds, a light froth or head gradually covers the surface of the soap, which is now a mass of small grains, and the process is complete. The supply of steam being stopped, the whole is allowed to rest for twenty-four hours, during which time the lee subsides. The soap is now removed by a ladle, and placed in moulds or frames made either of wood or iron. The wooden moulds are made by placing a series of wooden frames one upon another, each frame (technically called a lift) being five inches deep, forty-five inches long, and fifteen inches wide, resembling a box without a top or bottom. The whole are bound together and secured to an iron bottom by means of iron bars, so as to form a vat of the depth required, usually about sixty inches. The next operation upon the soap is called "crutching," and consists of stirring it with an implement called a "crutch," with the handle downwards, the effect being to give the soap an (sic) uniform and smooth appearance. The product is called white or curd soap. It is found by analysis to contain:—
Soda . . . . . . . . . . . . . . . . . . 6·96
Fatty Acids . . . . . . . . . . . . . 61·63
Water . . . . . . . . . . . . . . . . . 30·30
Iron, Alumina, Chloride,
and Sulphate of Sodium . . . 1·11
100·00 |
When the soap has remained in the frames for about a week, and has become hard, these are removed. It is then cut into layers by a wire, and divided into bars by a machine. After twelve hours it is ready for sale.
Primrose soap is made by saponifying the tallow in the same manner as for the white soap, and then adding a quantity of fine resin equal in weight to one-fourth of the tallow used, and continuing the operations in the manner before described. But as the soap containing resin, if framed in a state of curd, would be opaque and objectionable in appearance and colour, it is necessary to submit it to a further operation called "fitting." This process is effected by removing the lees from the bottom of the copper by a pump, and adding a quantity of water amounting to about five per cent. of the weight of the soap. The addition of water brings the soap into a perfectly liquid state, and after well boiling the steam is turned off, and the whole left to settle for forty-eight hours. The water does not continue mixed with the whole of the soap, but combining with a portion only (generally about twenty-five per cent.) sinks to the bottom of the copper, carrying with it the excess of alkali, together with the earthy and metalic salts and other impurities which may happen to be present. This deposit is call "nigre."
The supernatant soap is now transparent and of a lemon colour, containing by analysis:—
Resinous and Fatty Acids . . . . . . . . 62·00
Soda . . . . . . . . . . . . . . . . . . . . . . 6·96
Water . . . . . . . . . . . . . . . . . . . . . 30·50
Chloride and Sulphate of Sodium . . . 0·54
100·00 |
It is worthy of remark that a loss of resin occurs during its conversion into soap equivalent to forty per cent., and no method has been devised by which this loss can be remedied, nor has the subject received that consideration which it deserves.
The nigre remaining after the removal of the primrose soap is of a dark colour, and cannot be used again for the manufacture of the same kind of soap. It is, therefore, usually transferred to another copper, where it is mixed with a quantity of tallow and saponified as before. This addition partially obviates the defect, but, as the soap produced is not equal in colour to primrose soap, it is sold at a lower price under the name of extra pale.
The nigre from the extra pale soap is made into tallow crown by adding a quantity of brine, and boiling to a curd.
The brine is then removed by the pump and the soap fitted in the usual manner, no fresh material being employed. The nigre is returned to the succeeding boil of tallow crown. This soap, being much inferior in colour to extra pale, is sold at a lower price.
Various causes have been assigned for this deterioration in colour; by some it has been attributed to the presence of iron and alumina derived from the lees, but as this change in colour does not take place in a soap made without resin, it cannot be due to the mere presence of the metals, or to their combination with tallow. Others have thought that a much larger quantity of resin was present in the nigre than in the soap, and that this might cause the degradation in the colour, but as the tint is brown while the colour produced by resin is yellow, this explanation is not satisfactory. It may possibly arise from the action of the alkali upon some constituent of the resin, or from a combination taking place between the resin and the iron and alumina. When a cheap tallow soap is required, it is made by the addition of weak brine in the frames.
Palm oil in its natural state is of a red colour, which it is necessary to remove. This is effected by first melting the oil in a vat, and allowing it to stand for some time to deposit any impurity which may be present. It is then transferred to another vessel, and allowed to cool to 90 degrees Fahrenheit. To each ton of oil, 20lbs. of bichromate of potash, dissolved, and 56lbs. of hydrochloric acid, of 28 degrees Twaddell's hydrometer, are added; the whole is well stirred, and in about half-an-hour is found to be nearly free from colour.
Ten gallons of boiling water is now added, and the whole, after well stirring, is left to subside. The sesquichloride of chromium and chloride of potassium are found in solution in water at the bottom of the vat, and the oil is ready for use.
Crown pale is made from chronic bleached palm oil and fine resin, in the same manner as primrose soap.
YELLOW AND MOTTLED SOAPS. |
Mottled brown is made from palm oil bleached by nitric acid. This process is less expensive than the method of bleaching by bichromate of potash, and as an inferior and cheap resin is used, the soap is sold at a lower price than crown pale.
Third pale was at one time more largely consumed in the midland counties than any other variety of soap. Since the repeal of the duty, in 1853, better kinds have been substituted at a lower price, and third pale is now but little used. It is made by adding 3½ cwt. of weak brine to 16½ cwt. of crown pale. This addition is made in the frames.
Common yellow is made by adding 8 cwt. of weak brine to 12 cwt. of mottled brown soap in the frames. The effect of chloride of sodium and many other salts upon soap is curious. If an attempt be made to unite the latter with water, even at a boiling temperature, an immediate stiffening of the mixture takes place, and the whole becomes nearly solid, but if to this mixture a few pounds of common salt be added it will be brought to a state of perfect fluidity, and will not resume its former consistence until the temperature is reduced 130 degrees Fahrenheit. The production of a state of fluidity, however, is not the only result obtained by brine. It has the property of hardening soap to an extraordinary degree, even though a very small quantity be added, the effect of a few ounces of strong brine upon a ton of soap being quite perceptible.
First mottled is made in the same manner as white soap, the materials employed being tallow and kitchen stuff. The mottling is not produced by any artificial addition, but is, in fact, the nigre or metallic soap, which distributes itself in spots when the soap is allowed to undergo a semi-crystallisation by gradual cooling in large frames. In yellow soaps, the nigre is deposited in the coppers by the process of fitting, and in white soap is prevented from separating by rapid cooling. Popular prejudice, however, is in favour of this appearance in the description of soap, which was at one time a guarantee of genuineness, no method being known by which a mottle could be introduced into an adulterated soap. Since the repeal of the duty, many varieties of watered mottled have been manufactured and largely sold, the genuine mottled soaps being in this locality almost superseded by the adulterated ones.
ANALYSES OF MOTTLED SOAPS. |
A very hard and beautifully mottled soap was found, on analysis, to contain—
Fatty Acids . . . . . . . . . . . . . . . . . . . . . . . . 18·66
Water . . . . . . . . . . . . . . . . . . . . . . . . . . . 62·50
Soda . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4·24
Sulphate of Sodium . . . . . . . . . . . . . . . . . 0·67
Chloride of Sodium . . . . . . . . . . . . . . . . . 10·31
Silicic Acid . . . . . . . . . . . . . . . . . . . . . . . . 0·30
Iron and Alumina . . . . . . . . . . . . . . . . . . . 0·57
Organic matter and Glycerine . . . . . . . . . . 2·75
100·00 |
Whereas a genuine mottled soap contains—
Fatty Acids . . . . . . . . . . . . . . . . . . . . . . . . 62·00
Water . . . . . . . . . . . . . . . . . . . . . . . . . . . 30·00
Soda . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7·00
Iron, Alumina, Chloride, and Sulphate
of Sodium . . . . . . . . . . . . . . . . . . . . . . . 1·00
100·00 |
Crown mottled differs from first mottled in being made from bone grease only, and has the same percentage composition. Blue mottled, which is of recent introduction, is largely used in Birmingham and the surrounding districts. Its manufacture, which is of German origin, was first introduced into England by Mr. Kottula, superintendent of the works of Messrs. Blake and Maxwell, of Liverpool, who obtained a patent for the invention.
Messrs. Palmer, of London, some time afterwards commenced the manufacture of this kind of soap, and contested the validity of the patent in a court of law. It was well known in the trade that the patent was invalid, and in one case a manufacturer submitted to work under a license for which a large sum was paid rather than incur the expense of a legal contest. It was proved upon the trial that a description of the process had been published in a book written by a Mr. Kurten, and that soap had been made in London from directions contained therein. The patent was therefore declared to be invalid. Previous to the trial, the licenses under Kottula's patent were threatened with legal proceedings by another patentee, who asserted that Kottula's patent was an infringement upon one previously granted to him. The evidence produced upon trial was so conclusive that no further steps were taken.
The process by which blue mottled soap is made is as follows:— A quantity of palm oil, bleached by bichromate of potash, is saponified and boiled to a curd in the usual manner. The curd is then transferred to another copper, and a quantity of cocoa-nut oil, equal in weight to half the palm oil, is added, and saponified with twice its weight of lees at 34 degrees of density (Twaddell's Hydrometer). Some ultramarine blue is then added, and the soap, which is not in a state of curd, but in combination with all the water of the lees last used, is transferred to the frames. The ultramarine in cooling separates from the soap, and produces the mottled appearance. This soap contains, by analysis—
Fatty Acids . . . . . . . . . . . . . . . . . . . . . . . . 46·13
Water . . . . . . . . . . . . . . . . . . . . . . . . . . . 43·00
Soda . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6·85
Glycerine, Iron, Alumina, Chloride, and
Sulphate of Sodium . . . . . . . . . . . . . . . . 4·02
100·00 |
It should be borne in mind that the manufacturers do not derive any advantage from the practice of adulteration, which is adopted to enable the retailer to accommodate his price to the requirements of his customers.
The chief manufacturers of soap in this district are Messrs. T. Adkins and Co., Smethwick. There are also Messrs. Harvey and Co., Smethwick; and G. Smithson, Smallbrook Street, Birmingham.
