Bathgate oil works, 1865

The Shale Districts

The history of manufactures contains few more striking examples of the successful prosecution of commercial enterprise than those presented to us in the rise and progress of the extensive industries which the discovery of the peculiar properties of the Torbanehill mineral was the means of introducing into Linlithgowshire. Prior to the experiments resulting in the recognition of the fact that a new and valuable commodity could be obtained from coal, which had hitherto only been regarded as fuel, the manufactures of West-Lothian were comparatively unimportant, and its trade with the great marts of commerce inconsiderable. The discovery, however, some fifteen years ago, of the famous Boghead mineral about a mile from Bathgate, gave to West-Lothian a better position in the markets beyond its own borders, changed to some extent the physical aspect of many parts of the country, called into existence fresh fields of industrial labour, and introduced to daily life several most useful and valuable articles of consumption. Since the period of this discovery, quiet meadows have been invaded by the hum of the workshop; towns and villages have sprung up suddenly; a labouring population has inundated the shire; shafts have been lowered, stalks erected, railways constructed, and the face of the country blackened with smoke and the huge piles of refuse cast out from the pits and paraffine works.

The chief seat and centre of the new activity is Bathgate. This town, which is built upon the slope of a hill, may be said to lie in the very heart of that great bed of coal which stretches in a belt across Scotland, from the eastern to the western coast. Within the period since the great coal discovery, Bathgate has sprung into a place of considerable wealth and importance, and has quite changed its ancient appearance. In years anterior to the erection of the huge chimneys which now darken the air with their smoke, when the people were few, and the paraffine coal had not yet yielded up the secret of the rich qualities it possessed, the principal occupation followed by the population of the town was cotton handloom weaving in connection with the Glasgow factories.

With the opening of the coal-seams in the neighbourhood came the symptoms of a new and as yet undreamed of prosperity to the needy proprietors of the looms. An entirely different direction was given to the energies of the population, and a new era commenced in the history of the town. Fields of minerals were suddenly opened up in various parts of the district, the produce of which soon gave to the place a European celebrity, and converted the little country-town, that had so long lain peacefully on its sloping hill-side, into a busy and bustling hive. Small hamlets such as Armadale gradually swelled to the dimensions of bulky towns, and places which a few years previous were covered with waving crops were changed into thriving and populous villages. Although a large district was thus suddenly aroused to the prosecution of a remunerative industry, no place benefited more by the tide of unexpected fortune than Bathgate itself. The large quantities of coal and bituminous shale in the immediate neighbourhood of course decided its selection as the principal seat of the oil and paraffine manufactures. Large chemical works were established without delay, and were the means of opening up new sources of employment that proved highly beneficial to the inhabitants. The weavers of the place, too much accustomed to the pinching narrowness of poverty and whose average earnings had generally amounted to not much more than six shillings a-week, regarded the erection of the works with lively satisfaction. Little persuasion was requisite to make the greater number of them embark as workmen in the new enterprise, which promised them many and substantial benefits. The weaving was naturally thrown aside; and as the employment in the chemical-works required no apprenticeship to master its mysteries, the weavers, after a little practice and experience, became dexterous in their new labour, and were in a short time enabled to treble their former scanty earnings. The deep hold which the new industry took upon the district, and the practical success which it ultimately realised, are clearly shown by the fact that the population of the town and district of Bathgate, which was but 3,300 in 1851, is at present 10,000, being fully a threefold increase in less than a single decade.

The application of the Boghead mineral to the production of articles alike valuable and useful, and this too by a series of processes that were somewhat novel to science, naturally aroused considerable attention among the learned, and carried the reputation of the Bathgate minerals far beyond the limits of the county. The commodities extracted from the coal opened up a rich and quite undeveloped branch of commerce, and in various quarters of the world markets were found ready to receive at remunerative prices the manufactured articles which were turned out of the chemical works. In 1851 the works, which were destined to add threefold to the population and prosperity of Bathgate, were begun.

The Bathgate paraffine works thus so suddenly brought into existence are situated about a mile south-west of the town on the road leading to the iron-working village of Shotts. From the hill on which Bathgate is clustered, the distant confusion of roof-tops topped with belching chimneys forms a feature in the surrounding landscape of undulating fields which at once arrests the eye. The works, mapped out into various sections and departments, are spread over an area of twenty-five acres, and form what seems a huge, bustling, dusky village. Main streets of stills and retorts lead into branch thoroughfares of boilers and tanks. Clusters of sheds, stores and workshops, connected with different departments of the manufactory, and varying in shape and capacity according to the purposes they are devoted to, are met with in every direction. Branches of railway from the main lines in the vicinity cross and intersect each other in the grounds within the enclosure, converge at those points most favourable for the lading and unlading of goods, and bear along continuously loads of mineral from the pits, and great puncheons of oil from the stores. Immediately on the boundaries of the works, the visitor comes upon huge black mounds of waste formed by collecting the refuse of the coal cast out from the retorts and stills. Incessant accumulation of this waste has swelled the mounds into the dimensions of small hills, from the tops of which a far stretching view of surrounding country can be got with Bathgate in the distance. These waste-hills rise from the level of the ground in a gradual but steep incline, which increases in height as it recedes. Up the middle of this incline and iron tramway is led, along the lines of which small trucks, laden with refuse, are constantly dragged by horses, thus daily swelling the already overgrown heaps. Ceaselessly, day and night, the various stages of the manufacture are carried on, and the huge furnaces kept roaring by their attendants. Nor are the exertions of the gangs of workmen confined to the operations for producing the oil for which the place is so famous. Several subsidiary branches of manufacture are regularly carried on in addition to the staple one of the works. In one shed, a battalion of coopers shape hoops and staves, and bind together casks for the conveyance of the oil to be exported. In another, redolent of the blast of furnaces and the invigorating din of anvils, a large number of blacksmiths devote their skill to the fashioning of sundry articles of iron-work used on the premises. Sulphuric acid and soda, both of which articles are largely employed in the manufacture of paraffine, are made in other parts of the works.

The process by which the remarkable virtues are extracted from the Boghead mineral, and made in so material a degree to minister to the wants of domestic life, is, as may readily be imagined, complicated and laborious. The strange art of chemistry, which gives to science the power to change and transmute substances, and to reveal their hidden properties, so that they may be made useful to mankind, has seldom perhaps been employed in a more interesting, and in many respects wonderful, manufacture than that which is carried on at Bathgate. Delicately tinted wax candles and oil, almost as transparent as water, would seem to be the last things in the world which one would expect to see derived from coal; and yet this is not only done, but it is achieved in a way that raises our admiration by its perfection and ingenuity.

There are four different articles manufactured by Mr Young – viz., paraffine oil for burning, paraffine oil for lubricating machinery, a light volatile fluid called naphtha, and solid paraffine or wax. We shall endeavour to give a brief description of the various operations by which these are produced. The Boghead coal used in the manufacture is a hard, lustreless, rusty-black coloured mineral. By means of branch lines of railway, it is brought direct from the mouths of the pits on the Torbanehill estate into the heart of the works. When taken from the waggons, it is in masses of considerable size; and the preliminary step required in the process of manufacture is to break it into small pieces, to allow it to be shovelled conveniently into the retorts, and acted upon equally and uniformly by the heat. Entering a lofty shed, we see the huge crushing-machine in motion. This machine is formed of two large iron-toothed cylinders which revolve in opposite directions, and exert a force capable of breaking almost anything that comes within the influence of their formidable-looking teeth. The blocks of coal are fed into the machine in barrow-loads at one end, and the rollers, with their resistless, inevitable motion, gradually draw them in and crush them like twigs between their tusks. The broken coal falls into a pit below in pieces about the size of road metal, and is then ready for the introduction into the retorts. As it escapes from the machine, it is filled into trucks placed upon a "lift," and hoisted to the floor above. Ascending aloft with the trucks, we land with them upon an iron platform, and find ourselves in a a large iron-roofed shed up among the tops of the retorts, and under the guidance of another set of workmen. These retorts are vertical cast-iron tubes, 12 feet in length and some 14 inches in diameter. The retorts are divided into sets of four each, arranged in the form of a square, and each set is built into one furnace, and has a man specially appointed to superintend it. There are in all about fifty sets of retorts all constructed upon the same principle, and worked after the same method. The retorts rise about 3 feet above the platform to which the broken coal is hoisted, and their tops are shaped like common funnels, to facilitate the feeding of the coal into the tubes. The openings in the tops of these funnels are closed by spherical valves or lids, which are worked by counterpoised levers. The body of the retort or tube passes below the platform on which we are standing right down through the furnaces to the ground below; and the lower end is made air-tight by being led into a small pool of water. The charging of the retorts is a simple operation, and requires but little practice to enable it to be done with safety and dexterity. The truckloads of broken coals raised aloft from the pit of the crushing-machine are received by the man in attendance, and hurled along the platform to the particular set of retorts to be charged. Arrived here, the funnels of the retorts are filled with coal, and the spherical lid closing the orifice is depressed, which causes the coal to fall suddenly into the retort. When the retorts are thus filled, the lid is again raised, by using the counterpoised lever, and the opening is made air-tight by having fine sand sprinkled over the joint. Having seen the retorts thus fully charged with coal from the top, we descend from the elevated platform to the grounds below, to take a glance at the management of the furnaces. The workmen in charge of these are careful and attentive in the discharge of their simple duties; for on the proper discharge of them depends much of the success of the future operations. A low red heat is constantly kept up, just sufficient to promote the distillation of the coal in the retorts, care being observed to keep the temperature precisely at the requisite height. The coal which we saw filled in at the top of the retort falls down the tube as it is acted upon by the heat till it reaches that part of the tube which passes through the furnace. Here the decomposition of the coal is effected, and oil produced in the shape of vapour, which passes of by a pipe. The refuse material left behind falls further down the tube till it passes out at the bottom into the pool of water, and is there raked away. The vapours as they are generated by the furnace pass into a large main iron pipe, to undergo the process of condensing. This pipe runs along the entire length of the sheds where the retorts are situated, and leads into the condensers placed outside in the open air. These condensers are constructed upon the self-same principle as those employed in gas works, and consist of a series of pipe on the syphon principle, standing in vertical rows. The vapours, in passing through these pipes, are acted upon by the coldness of the atmosphere, and became condensed into a liquid. A small portion of the vapours is always incondensable. This is collected into a gas-holder, and is used for lighting the workshops. The condensed liquid portion is run off from the pipes into an immense reservoir or brick stock-tank sunk into the ground, and which, when full, is capable of holding 100,000 gallons. The crude oily liquor thus collected is a thick, black, greasy fluid, not unlike tar, that moves with a sluggish motion when stirred, and gives off inflammable vapours at the usual atmospheric temperature. The collection of this artificial petroleum into the great brick reservoir completes the first part of the process which the Boghead coal goes through in its wonderful transformation into pure oil and paraffine. The crude oil is only drawn off when required, and as there is often an immense quantity in the tank, precautions against fire are necessary; and such a calamity is avoided by the exercise of every possible care and precaution. The vapours given off by the oil when in its crude state are highly inflammable; the primary object to be secured, therefore, is to prevent as much as possible their contact with the atmosphere. The tank is accordingly covered with a sheet-iron roof, and the doors, formed of the same material, are so constructed as to make the tank perfectly air-tight. To obviate still further the risk of a disastrous conflagration, an iron pipe is led through the roof of the tank, by means of which, in the event of the oil becoming ignited, a strong jet of steam could be injected into the reservoir, and the flames thus quenched.

We pass on now to the second step in the elaborate operations. Having witnessed the part which the retorts have to perform, the stills come next under our observation. The crude oil, when taken from the stock-tank to undergo its first purification, is pumped up into large receptacles at a considerable height from the ground. These receptacles, connected with the stills by means of pipes, are raised aloft for the purpose of filling the stills easily, as the oil then flows down the pipes from the superior height into the stills by the mere force of gravitation. The stills are cylindrical in shape, and are of great strength and dimensions. They are fixed in a horizontal position above the furnaces, and are built in rows forming small streets. When the stills are filled with the crude oil, the doors are closed, and the joints made air-tight with clay. This satisfactorily accomplished, the fire is applied from below, and a regular heat is carefully maintained. This is kept up till the oil is distilled over, and passes once more into vapour. The vapour, as in the preliminary process, is made to pass through iron pipes, which are sunk in small ponds of water for the purpose of attaining the proper degree of coldness to act upon the product of the distillation. In its passage through these pipes, the vapour is re-condensed into liquid, and flows into tanks prepared to receive it. The collection of the oil in this state completes the process of the first purification of the crude liquor. Thus collected, the fluid shows marked signs of the improvement it has undergone by the vigorous measures to which it has been subjected. When filled into the stills, it was dirty black in colour, and of a thick sluggish consistency; now it is dark-green in colour, and greatly thinner. The impurities which have been extracted from it are left behind in the still in the shape of a black, lustrous, compact residue, resembling the coked burned in locomotives. This coke makes excellent fuel, and as such is employed in the works.

The second process of purification to which the oil is subjected after passing the ordeal of the stills, is of an entirely different nature from the first, and to witness this we must pass to another part of the works. We enter a long narrow building filled with circular cast-iron tanks, ranged like a row of boilers down its entire length. The dark-green oil in the condition in which it left the stills is run into these tanks till they are nearly filled, after which a certain quantity of strong sulphuric acid is added. The acid is employed to separate the impure substances from the oil; but in order to accomplish this, it is essential that both fluids should be thoroughly mixed up and assimilated as nearly as possible. This is a work of some difficulty, because of the difference in the specific gravity of the two liquid, the oil being greatly the lighter, and having the tendency to float on the top. To overcome this disadvantage, each tank is fitted up with a revolving stirrer. This is moved rapidly by machinery, and puts into commotion a series of blades that agitate the liquor violently, and give to it something of the motion of boiling water. For four hours the dissimilar fluids are fiercely and rapidly beaten about, and their peculiar properties brought to act on each other, until, under the biting influence of the acid, the dark-green oil changes to pale green, and gives token of having parted with much of the grosser substances that had rendered it dull and opaque. The prescribed time having expired, the stirrers are stopped, and the liquor is allowed to settle, which causes the organic impurities separated from the oil by the action of the vitriol to collect in the bottom of the tanks. The lees are in the shape of a kind of black coarse acrid tar, which is drawn off from the tanks, and subsequently used as fuel.

The oil, thus far cleansed of its foulness, is now transferred to clean tanks, mixed with a strong solution of caustic soda, and again undergoes violent agitation with the stirrers. This operation, which constitutes the third stage of purification, has the effect of neutralising any sulphuric acid that may remain in the oil, and separating from it another lot of impurities. The cleansing satisfactorily accomplished, the liquor in the tanks is allowed to settle as in the former case, and the refuse is drawn off. The oil is then pumped back into the stills, distilled a second time, and re-transferred to the tanks, and again subjected to the action of the acid and soda.

The effective system of distillation and purification which the oil has by this time gone through has had the effect of bringing it to a comparative state of purity. The blackness has been gradually extracted from it, it has been made less opaque, and has now assumed a clear pale yellow colour, contrasting wonderfully with the foul slimy appearance which it presented on being pumped from the great brick reservoir. When in this state, the oil contains the elements of no less than four different products, each of which is possessed of its own commercial value. To separate these, so as to make each available as an article of commerce, is the next care of the oil makers. This result is achieved by again distilling the oil at various temperatures.

At the lowest temperature the lightest and most volatile parts of the oil pass off in the form of vapour. These vapours, on being cooled by passing through the pipes, yield a liquid which, on being distilled by itself, gives a light, transparent, inflammable fluid known by the name of naphtha. The specific gravity of this naphtha is considerably less than that of the naphtha derived from coal-tar. It constitutes a valuable article of commerce, and is largely employed for various useful and economic purposes. The proprietors of itinerant booths and caravans use it as their chief illuminating agent, as it is easily carried about, and gives forth a strong glaring flame not easily extinguished by the wind. Street huxters who have to display their wares sub Joʈe employ it for the same purpose, as likewise do workmen engaged in tunnelling and works of excavation. The paraffine naphtha is also an admirable substitute for turpentine, and is used to a great extent in india-rubber works for dissolving the substances that are employed in that important branch of modern manufactures.

The naphtha being thus carefully separated from the oil in the manner explained, the next step is to take off the second product in point of volatility. To effect this, the temperature in the stills is considerably elevated, and the vapours which come over are collected and distilled, and yield paraffine or illuminating oil. This oil is separately put through the process of distillation and purification till it obtains the requisite degree of clearness. When ready for the market, it is a transparent liquid, almost colourless, and nearly free from smell. It is the most valuable and important of all the articles manufactured at Bathgate, and is known far and wide for its beautiful illuminating qualities. In country districts, where no gas is manufactured, the paraffine has almost entirely superseded all other kinds of oil; and is universally admired for the clearness and brilliancy of the light which it affords. When lighted, it gives forth a fine, transparent, lambent white light, peculiarly free from glare, and mild and pleasant to the eye. Markets for the sale of the oil have been opened up in all quarters of the globe; and the demand for it has increased to such an extent as to raise the district around Bathgate to wealth and position, and keep in active operation the largest chemical work in Great Britain. The greatest demand for the refined oil is of course during the winter months; and as the drain upon the works at this period of the year is very great, it is found necessary to keep large quantities in stock. For this purpose, a number of iron tanks, similar in outward appearance to gasometers, each capable of holding 100,000 gallons, have been erected within the works. During the summer months, when the demand for the oil has slackened, these huge reservoirs are filled with oil, which is kept carefully stored against the winter. The superior excellence of the paraffine oil over all other descriptions of burning oils is a point that has been decided by the testimony, founded on experiment, of distinguished men of science. A gallon of this oil weighs about 8½ lb.; in point of illuminating power is nearly equal to one gallon and a quarter of American native petroleum oil; and it can be purchased at a price which gives a light cheaper than English coal-gas. Another, and not the least important virtue which this paraffine oil possesses, is the safety with which it can be used for domestic purposes. So ample are the precautions employed to separate the last particle of naphtha from it that there is no risk of explosion, and it may be used under any circumstances with the greatest safety.

A yet higher temperature than what was necessary for the production of the burning oil produces a thick heavy lubricating oil. This oil, when it comes over from the still, is in reality a mixture of oil and solid paraffine, and on being allowed to cool, acquired the consistency of grease. When warm, the thick oil, containing crude particles of paraffine floating in it, is collected in open tanks and allowed to cool. The cold causes the paraffine to crystallise, and the step next taken is to separate the oil from the paraffine. This important operation is performed in another department of the works. The heavy oleaginous liquid, when thoroughly cooled, is poured into strong canvas bags, and these, when filled, are placed in hydraulic presses. The pressure is then applied with such force that the oil is squeezed out of the bags, leaving the solid paraffine inside. The oil which the strong pressure filters through the bags, flows into receptacles prepared for it beneath the presses, and the fluid thus obtained is known as the lubricating oil. This oil is admirably adapted for the purposes which have given it its name. Large quantities of it are used in the Lancashire cotton factories for oiling the more delicate machinery, and it is held in much esteem by watch and clock makers, philosophical instrument makers, and other tradesmen, the fineness of whose work requires oil of a superior quality. The lubricating oil has the advantage over whale oil, inasmuch as, with lapse of time, it shows no tendency to rancidity, and is free from the qualities which in all other vegetable and animal oils cause spontaneous combustion.

We come now to consider the fourth and last product of Boghead coal – solid paraffine. This remarkable substance derives its name from two words, which indicate its want of affinity with almost all the other chemical bodies. As finally purified, paraffine is a fine milk-white substance, much more transparent than wax, and of a beautiful lustrous structure. It lacks both taste and smell, burns with a luminous white flame without giving out smoke, and, when thoroughly consumed, leaves nothing behind in the shape of refuse or waste. Before reaching this degree of purity, however, it has to undergo a regular series of cleansing operations. In its crudest state we saw it first when separated from the lubricating oil by means of hydraulic pressure. On being emptied from the bags, it is seen in its coarsest state, and is then of a dirty yellow colour. This hue is derived from the large quantity of oily matter it contains; and to extract this successfully, the care of the workman is next directed. This result is effected by the repetition of a single process. The paraffine is placed in cast-iron vessels, dissolved in heated naphtha, and kept in solution for a considerable time in order to allow the naphtha to act upon the impurities contained in it. The liquid is then allowed to cool, and the paraffine to crystallise again. The cold liquor is once more strained through canvas bags, and the oil squeezed out as in the former operation. When shaken from the bags a second time, the crystals of paraffine are found to have changed colour from yellow to dirty white, and are consequently so much the purer. The operation of dissolving the paraffine in naphtha, cooling it, and filtering it through the bags, is repeated till it has acquired the requisite whiteness and purity. This finally achieved, the paraffine is transferred to another department of the works, the odour of naphtha with which it is impregnated is driven off by steam, and the paraffine in a liquid state is run into circular cast-iron moulds to cool. When thoroughly crystallised, the paraffine is lifted out of the mould in thick round cakes, and is carried to the packing department, where it is stowed into casks, and sent off to the markets.