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The Uphall Mineral Oil Works

 

The development of the mineral oil manufacture forms one of the most remarkable chapters in the history of modern industry. Only a quarter of a century has elapsed since attention was directed to the subject through the discovery of an oil spring in Derbyshire; and now we have a great trade giving employment to many thousands of persons, and producing, from a substance formerly reckoned valueless a most important addition to the material comforts of the country. The pioneers in the enterprise were Mr James Young and Mr Edward Meldrum. In their hands the little Derbyshire spring, which had been discovered by Dr Lyon Playfair, became so valuable that, when its supply gradually ceased, they found it worth while to manufacture oil of a similar character from cannel coal. By-and-by it was discovered that the product in question could be obtained from shale, and forthwith the trade, which by this time had been established at Bathgate, assumed an extent commensurate with the abundance and cheapness of the raw material. After the first flush of prosperity, a check was experienced through the introduction of American petroleum, a substance resembling the shale oil in many important particulars. In course of time, however, matters found their level; and now, in spite of foreign competition, our home manufacture of mineral oil and its products presets all the appearance of a thriving branch of industry.

In August last, in connection with the visit of the British Association, we had occasion to describe the extensive works at Addiewell, where the trade was carried on in all its branches under the supervision of Mr Young, one of its original founders. At a distance of a few miles, Mr Meldrum, another partner in the old Bathgate venture, presides over a similar manufactory, which is rapidly extending its operations under the auspices of a recently formed joint stock company. The Uphall Mineral Oil Works, which, till within the last few months, belonged to Messrs Peter M'Lagan, M.P., Edward Meldrum of Dechmont, and George Simpson, Benhar Colliery, were established in 1866. Situated in close proximity to the Edinburgh and Bathgate Railway, they cover 38½ acres of ground, and comprise, besides a prolific shale pit, all the necessary appliances for manufacturing crude oil, and obtaining the various products resulting from the refining of that article. The shale and other mineral fields connected with the works extend to about 2000 acres, and the quantity of crude oil produced exceeds a million gallons per annum. The undertaking of the firm referred to also embraced the Boghall works, with mineral fields extending to 3000 acres, and apparatus capable of producing 900,000 gallons of crude oil per annum. In the spring of the present year, the original copartnery was merged in a limited liability company, having for its object the extension of the undertaking by the acquisition of the Hopetoun shale field, and the combination of the various works, so as to carry on the manufacture to the greatest possible advantage.

The arrangement adopted is to work the shale in all the fields simultaneously, and to manufacture the crude oil in each case in the immediate vicinity of the pits. The process of refining is confined to the Uphall works, to which the crude oil from Boghall and Hopetoun is conveyed by railway. It is therefore only at Uphall that one can witness the complete series of operations by which a dull rusty-looking stone is converted into the finest burning and lubricating oils, not to speak of various other products about as unlike the original substance as it is possible to imagine.

A visitor to the Uphall works – more especially if he should fall into the courteous hands of Mr Meldrum, who delights in explaining everything aborigine – would probably find himself conducted in the first instance to the shale pit, where a steam-engine is constantly employed in hauling up from a depth of 27 fathoms supplies of the raw material, the quantity brought to bank varying from 120 to 130 tons per day. Shale is no doubt familiar to most readers as a stone of slaty texture and dusky-brown colour. The best kind is that which does not weigh too heavy, and which, when cut with a knife, does not splinter, but gives off a continuous shaving, such as would be got from a piece of wax. On reaching the pit bank, the shale is tumbled into a hopper, and falls between two cylinders armed with strong iron teeth, by whose revolution it is broken into small pieces suitable for the first stage of the manufacture. The crushed shale drops into wagons placed underneath the cylinders, and is conveyed along a tramway to the retorts, where it undergoes a process of distillation. Of these retorts there are two kinds in use at Uphall – One closely resembling that used in gas works, and the other of a somewhat more complex character, calculated to do its work with greater thoroughness. The latter being the form of apparatus most extensively adopted, it may suffice to describe the distillation with reference to its mode of action. The retort is a flattened cylinder of cast-iron, about twelve feet long, contracting itself towards the ends, both of which, however, are open. It is placed in an upright position in a framework of brick, so that nearly the whole of its length may be exposed to the flames of a furnace playing through a wide flue. The upper end is fitted with a hopper, the orifice of which can be tightly closed at pleasure by an ingenious contrivance, and the lower end dips to the depth of two or three inches into a shallow pan filled with water. So adjusted, the retorts are ranged in long rows, a platform communicating with the shale pit tramway giving access to their hoppers. The retort having been filled with broken shale, the furnace is brought into operation so as to raise its middle zone to a low red heat, and then the process of distillation goes on continuously. At the temperature referred to, which has to be carefully maintained throughout, the hydrocarbons contained in the shale are driven off in the shape of gas, which is to a large extent condensable. Under a greater heat they would take the form of permanent gas, and so the production of oil would be frustrated. The shale in the retort is kept moving by the addition at intervals of fresh material through the hopper at the top, and the regular raking away of that which falls out into the water pan below. As it slides gradually down into the heated zone, it parts with its hydrocarbons, and by the time it reaches the bottom of the retort is reduced to the state of worthless refuse. The evolution of the gaseous matter is promoted by the introduction of a jet of steam, and the product of the distillation, which is prevented by the water from escaping at the bottom of the retort, passes off through a pipe near the top, and flows into the condensers. These are of two kinds, one consisting of a congeries of winding pipes, in passing through which the gas is exposed to the cooling influence of the atmosphere, and the other of a long wrought-iron cylinder, with a stream of cold water constantly flowing along its upper surface. The efficiency of the condensers varies with the season of the year; but in no case do they suffice to condense the whole of the vapour passed into them. A considerable portion has to be blown off as permanent gas, which, however, is turned to account for lighting up the works at night, as also in helping to heat the furnaces, and so economise fuel. The product of the condensation runs off in a continuous stream of dark-greenish fluid, which is first conveyed to an apparatus called a "separator," in order that its two components of oil and water may be parted one from the other. In the separator, which is simply a small tank with outlets at different levels, the oil rises to the top, and is carried away by one pipe, while the water, of which there is about the same quantity, escapes by another. This water contains a considerable quantity of ammonia, which, being treated with sulphuric acid, forms the valuable agricultural product known as sulphate of ammonia. The sulphate is produced at Uphall to the extent of about seven tons per week, and, finding a ready sale among the neighbouring farmers at something like £22 per ton, forms no inconsiderable item in the revenue of the company.

The crude oil, on leaving the separator, is conveyed to a reservoir containing about 50,000 gallons, where is stored not only the product of the Uphall retorts, but also the oil produced at the company's other works, which is brought by rail in tanks specially constructed for the purpose. In the process of purification to which the oil is now subjected, the first step is a second distillation. The dark green fluid is pumped from the reservoir into large iron pans, in which it is boiled to dryness. The hydro-carbons are thus once more driven off in the form of gas, which, being condensed, yields an oil still greenish in colour, but thinner, lighter and altogether considerably purer than the crude material. In the pans there is left a deposit of charcoal capable of being used as fuel in the furnaces. In its next stage the oil passes to a department of the works where it undergoes a sort of scouring process. The first step is to introduce it to a set of closed vessels, where it is stirred up with sulphuricacid. On being run off into a settler, the oil, considerably improved in appearance, rises to the top, while ablack tar, formed by the combination of the sulphuric acid with various impurities, subsides to the bottom. A similar treatment with caustic soda results in as second deposit of black tar and a further purification of the oil, which is then passed on by pumps to undergo a third distillation. Of the tar produced in the process just described, a portion in used in heating the furnaces, but the greater part is subjected to analysis with the view of recovering its more valuable components. Thus the soda tar is boiled down to dryness, giving off a certain quantity of gas, which is condensed into oil. A black deposit which remains in the still is burned in a furnace, so as to get rid of its carbonaceous matter; and the residue, being dissolved in water and boiled down, yields back a considerable portion of the soda which had been used in the scouring of the oil. To render it caustic, the soda is treated with lime, the latter substance being itself converted by the process into carbonate of lime, which again assists in the fusion of the waste soda recovered from the soda tar. The whole process is a remarkable illustration of the indestructibility of matter, and shows how, in the hands of a chemist, even the so-called waste products resulting from manufacturing processes can be turned to profitable account.

Following the progress of the oil, we find that on the third distillation it once more leaves a black deposit, and comes out in a state of considerable purity. Vitriol and soda are again applied as before; then further distillation; and so on until the oil, from a muddy, greenish substance, of the consistency of soup, is converted into a thin, light, and perfectly transparent fluid. The appearance of the finished oil depends, of course, on the extent to which the process of purification is carried. At Uphall, two qualities are produced. One of these, of a light amber colour, possesses all the properties of a first-rate burning oil; and it is in this state that the great bulk of the produce of the works is sent to market. From this oil, however, by additional distillation and bleaching, there is produced one, all but perfectly colourless and indorous, and which, though no way superior, nay, in some respects, inferior, to the other for burning purposes, is preferred by those who can afford to give a higher price for a finer-looking article.

To pass to another branch of the manufacture, it is necessary to explain that, in course of the various distillations to which reference has been made, a certain proportion of the oil has been regularly set aside as unsuitable for burning. This is the thicker and heavier oil which comes towards the close of the distillation, after the lighter and more volatile portion has been given off, and which the attendant workman takes care to direct into a separate reservoir. Thus, starting with 100 gallons of crude oil, something like 80 gallons would be passed as suitable for burning; while the remaining 20 would be relegated to a different destination – that is to say, to the production of solid paraffin and of lubricating oil. The former of these objects is effected by a process of freezing, carried out by a very ingenious mechanical contrivance. A piston worked by a steam-engine is moved to and fro in a large cylinder, causing alternate compression and expansion of the air at one end or the other. The air when under pressure is deprived of its heat by the application of a stream of cold water, and, on its being again allowed to expand, the effect of intense cold is instantaneously produced. This refrigerated air is brought to bear on a stream of brine, which it converts into a freezing mixture, and in this way is obtained a means by which paraffin may be readily produced in the warmest days of summer. The substance in question remains in solution at a temperature of 60, but when the temperature is reduced to 32 it, so to speak, coagulates into the solid form. In order to bring about the requisite conditions, the thick heavy oil of which we have spoken is conveyed into cylindrical vessels, which can at pleasure be enclosed in a jacket of freezing brine. After due exposure to the cold, the fluid, now of the consistency of treacle, is run off into bags of coarse canvas. These are flung down and allowed to lie for some time, during which the oily matter percolates through the interstices, while the solid paraffin remains behind. The bags are then taken up and put under pressure, which forces out more oil, and leaves the paraffin in the shape of a mass of flakes or scales of a dull greenish-yellow colour. A powerful hydraulic press is next brought into requisition, and the scale paraffin, after being subjected to its action between layers of wicker work, comes out in dry cakes ready to be sent to market as crude paraffin. Hitherto the output of crude paraffin at the Uphall Works, amounting to eight or ten tons per week, has been disposed of in that state, realising somewhere about £30 per ton. The company are now, however, erecting works for the manufacture of paraffin candles, in which the material will be still more profitably disposed of. In the manipulation of paraffin, the first process is that of purification. The crude material is dissolved in heated naphtha and then allowed to crystallise; and this process having been repeated two or three times, and the smell of the naphtha driven off by steam, the paraffin comes out a pure, white, odourless substance, ready for the manufacture of those beautiful candles which, with the additional advantage of cheapness, rival the excellencies of sperm.

The oil left over from the manufacture of solid paraffin in carefully collected, and subjected to processes of scouring and distillation similar to those above described. The product is a pure, yellow, odourless oil, of considerably thicker consistency than that appropriated for burning, and of a greasy nature, which renders it suitable for lubricating machinery. As compared with animal oils, this substance has the advantage of not being liable to become rancid. It may be exposed to atmospheric influences for any length of time without getting oxidised, and consequently, through rather thin for very heavy bearings, it is peculiarly well adapted for oiling light spindles, such as are so extensively used in cotton and flax mills.

Having threaded our way through the various manufacturing departments, we come now to those portions of the works in which the produce is tested, stored, and made ready for sending out to the consumer. The first of these operations is conducted in a detached laboratory, where a chemist is constantly employed in making the necessary experiments. According to the Act of Parliament regulating the trade, no oil that has a firing point under 100 can be sold without a cautionary label, or by any person not holding a licence authorising such sale. By the "firing point" is meant the temperature to which the oil must be raised before it begins to give off a gas which will ignite on the application of a flame. In speaking of paraffin oil, it should be distinctly borne in mind that that substance is not, properly speaking, explosive. Throw a lighted match into a cupful of it, and the flame is at once extinguished, just as if it had been immersed in water. At an ordinary temperature, the oil only burns when diffused through a wick, or spread over a surface, or otherwise distributed so that, its particles being freely exposed to the atmosphere, it may evaporate or resolve itself into inflammable gas with considerable rapidity. By raising the temperature, this conversion into gas is accelerated, and after a time a point is reached at which, even in bulk, the oil gives off so much gas as will produce a series of flashes when a flame is applied near its surface. Let the heating process be carried still further, and at length the evolution of gas, say from a cupful of oil, becomes sufficiently rapid to maintain a permanent flame. The degree of heat at which the flashing takes place is, as we have said, technically known as the "firing point;" that at which the gas from a body of oil burns continuously is called the "point of permanent ignition." While, therefore, the oil itself cannot be exploded, it will readily be seen that the gas given off from it has only to be combined, as in the case of common coal gas, with a certain proportion of air, to produce an explosive mixture. Oil at a high temperature will give rise to these conditions more rapidly than the same oil at a lower temperature; and the safest oil is obviously that whose "firing" or flashing point is highest – that is to say, which can be raised to the greatest degree of heat without giving off enough gas to produce an explosion. The Legislature, as has been stated, prescribes a firing point of 100 as the lowest at which oil can be freely sold. The oil produced at Uphall runs so high above this standard that testing seems almost a work of supererogation. Nevertheless, a sample of each day's make is regularly set aside for the laboratory, and its firing point duly ascertained; so that, in case of any complaint from purchasers, there may be an authoritative record to fall back upon to prove that, under proper conditions, the oil is of a perfectly innocuous character. The process of testing is carried out by means of a simple apparatus, of a size and form accurately prescribed by statute. A tin vessel, four inches in diameter, and as many deep, is nearly filled with water, into which is inserted a cup, 2in. in diameter, and 2in. deep, containing the oil to be tested. At the outset of the experiment, the water must show a temperature of 80, which, of course is communicated to the oil in the cup. By the application of a spirit lamp underneath, the temperature is gradually raised, as indicated by a thermometer inserted in the oil, and the operator from time to time applies a small flame at the distance of a quarter of an inch above the surface of the fluid, to ascertain if sufficient gas is rising to produce ignition. By-and-by, the approach of the flame produces a flash over the surface of the oil, and the degree of the thermometer at which this takes place is read off and recorded as the firing point of the sample in question. In the case of the Uphall oil, the firing point generally ranges from 110 to 120. When we saw the experiment made, it ran up as high as 132, the point at which the gas formed a permanent blaze being 10 higher, or 142. Such oil, it is clear, affords all the conditions of perfect safety, and may be sold without any licence or guarantee. Besides the oil destined for burning, the chemist also takes cognisance of that intended for lubricating purposes. In regard to the latter, there is no question of explosion, but it must pass a test showing that it has a specific gravity of 890, being nearly 9 lb. to the gallon.

Having passed the ordeal of the laboratory, the oil is ready to be sent out for consumption. Pending orders, it is stored in huge tanks, holding 100,000 gallons a piece, situated in a remote corner of the works. For delivery to the trader, it has to be run into barrels, and this brings us to the cooperage, which presents some features of special interest. In this department a number of men are constantly employed in overhauling the empty barrels which have been sent in to be refilled. The oil being of a very searching nature, these require to be made thoroughly tight in all their seams. Nor is this all, for the penetrating fluid would make its way into the substance of the wood unless the inside of the barrel were covered with a protective coating. The necessary material is found in common glue, on which it seems the oil has no action. A quantity of liquid glue is run into each cask, and rolled about inside until it has coated the whole interior, when the remainder is poured out. The glue serves the double purpose of giving an impermeable lining to the cask, and showing by its leaking through, while yet in a liquid state, any weak point requiring to be made good by the cooper. When ready for filling, the barrel is put on the scales, and a note taken of its weight. A second weighing when full gives, of course, the weight of oil run in, from which the contents in gallons can be readily ascertained. – Scotsman.

 

The Falkirk Herald and Linlithgow Journal, December 28th 1871 - Reprinted from the Scotsman

 

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