While the Carron foundry was pursuing a career of safe prosperity, Dr.

Roebuck's enterprise led him to embark in coal-mining, with the object of securing an improved supply of fuel for the iron works. He became the lessee of the Duke of Hamilton's extensive coal-mines at Boroughstoness, as well as of the salt-pans which were connected with them. The mansion of Kinneil went with the lease, and there Dr.

Roebuck and his family took up their abode. Kinneil House was formerly a country seat of the Dukes of Hamilton, and is to this day a stately old mansion, reminding one of a French chateau. Its situation is of remarkable beauty, its windows overlooking the broad expanse of the Firth of Forth, and commanding an extensive view of the country along its northern sh.o.r.es. The place has become in a measure cla.s.sical, Kinneil House having been inhabited, since Dr. Roebuck's time, by Dugald Stewart, who there wrote his Philosophical Essays.[3] When Dr.

Roebuck began to sink for coal at the new mines, he found it necessary to erect pumping-machinery of the most powerful kind that could be contrived, in order to keep the mines clear of water. For this purpose the Newcomen engine, in its then state, was found insufficient; and when Dr. Roebuck's friend, Professor Black, of Edinburgh, informed him of a young man of his acquaintance, a mathematical instrument maker at Glasgow, having invented a steam-engine calculated to work with increased power, speed, and economy, compared with Newcomen's; Dr.

Roebuck was much interested, and shortly after entered into a correspondence with James Watt, the mathematical instrument maker aforesaid on the subject. The Doctor urged that Watt, who, up to that time, had confined himself to models, should come over to Kinneil House, and proceed to erect a working; engine in one of the outbuildings. The English workmen whom he had brought; to the Carron works would, he justly thought, give Watt a better chance of success with his engine than if made by the clumsy whitesmiths and blacksmiths of Glasgow, quite unaccustomed as they were to first-cla.s.s work; and he proposed himself to cast the cylinders at Carron previous to Watt's intended visit to him at Kinneil.

Watt paid his promised visit in May, 1768, and Roebuck was by this time so much interested in the invention, that the subject of his becoming a partner with Watt, with the object of introducing the engine into general use, was seriously discussed. Watt had been labouring at his invention for several years, contending with many difficulties, but especially with the main difficulty of limited means. He had borrowed considerable sums of money from Dr. Black to enable him to prosecute his experiments, and he felt the debt to hang like a millstone round his neck. Watt was a sickly, fragile man, and a constant sufferer from violent headaches; besides he was by nature timid, desponding, painfully anxious, and easily cast down by failure. Indeed, he was more than once on the point of abandoning his invention in despair. On the other hand, Dr. Roebuck was accustomed to great enterprises, a bold and undaunted man, and disregardful of expense where he saw before him a reasonable prospect of success. His reputation as a practical chemist and philosopher, and his success as the founder of the Prestonpans Chemical Works and of the Carron Iron Works, justified the friends of Watt in thinking that he was of all men the best calculated to help him at this juncture, and hence they sought to bring about a more intimate connection between the two. The result was that Dr.

Roebuck eventually became a partner to the extent of two-thirds of the invention, took upon him the debt owing by Watt to Dr. Black amounting to about 1200L., and undertook to find the requisite money to protect the invention by means of a patent. The necessary steps were taken accordingly and the patent right was secured by the beginning of 1769, though the perfecting of his model cost Watt much further anxiety and study.

It was necessary for Watt occasionally to reside with Dr. Roebuck at Kinneil House while erecting his first engine there. It had been originally intended to erect it in the neighbouring town of Boroughstoness, but as there might be prying eyes there, and Watt wished to do his work in privacy, determined "not to puff," he at length fixed upon an outhouse still standing, close behind the mansion, by the burnside in the glen, where there was abundance of water and secure privacy. Watt's extreme diffidence was often the subject of remark at Dr. Roebuck's fireside. To the Doctor his anxiety seemed quite painful, and he was very much disposed to despond under apparently trivial difficulties. Roebuck's hopeful nature was his mainstay throughout. Watt himself was ready enough to admit this; for, writing to his friend Dr. Small, he once said, "I have met with many disappointments; and I must have sunk under the burthen of them if I had not been supported by the friendship of Dr. Roebuck."

But more serious troubles were rapidly acc.u.mulating upon Dr. Roebuck himself; and it was he, and not Watt, that sank under the burthen. The progress of Watt's engine was but slow, and long before it could be applied to the pumping of Roebuck's mines, the difficulties of the undertaking on which he had entered overwhelmed him. The opening out of the princ.i.p.al coal involved a very heavy outlay, extending over many years, during which he sank not only his own but his wife's fortune, and--what distressed him most of all--large sums borrowed from his relatives and friends, which he was unable to repay. The consequence was, that he was eventually under the necessity of withdrawing his capital from the refining works at Birmingham, and the vitriol works at Prestonpans. At the same time, he transferred to Mr. Boulton of Soho his entire interest in Watt's steam-engine, the value of which, by the way, was thought so small that it was not even included among the a.s.sets; Roebuck's creditors not estimating it as worth one farthing.

Watt sincerely deplored his partner's misfortunes, but could not help him. "He has been a most sincere and generous friend," said Watt, "and is a truly worthy man." And again, "My heart bleeds for him, but I can do nothing to help him: I have stuck by him till I have much hurt myself; I can do so no longer; my family calls for my care to provide for them." The later years of Dr. Roebuck's life were spent in comparative obscurity; and he died in 1794, in his 76th year.

He lived to witness the success of the steam-engine, the opening up of the Boroughstoness coal,[4] and the rapid extension of the Scotch iron trade, though he shared in the prosperity of neither of those branches of industry. He had been working ahead of his age, and he suffered for it. He fell in the breach at the critical moment, and more fortunate men marched over his body into the fortress which his enterprise and valour had mainly contributed to win. Before his great undertaking of the Carron Works, Scotland was entirely dependent upon other countries for its supply of iron. In 1760, the first year of its operations, the whole produce was 1500 tons. In course of time other iron works were erected, at Clyde Cleugh, Muirkirk, and Devon--the managers and overseers of which, as well as the workmen, had mostly received their training and experience at Carron--until at length the iron trade of Scotland has a.s.sumed such a magnitude that its manufacturers are enabled to export to England and other countries upwards of 500,000 tons a-year. How different this state of things from the time when raids were made across the Border for the purpose of obtaining a store of iron plunder to be carried back into Scotland!

The extraordinary expansion of the Scotch iron trade of late years has been mainly due to the discovery by David Mushet of the Black Band ironstone in 1801, and the invention of the Hot Blast by James Beaumont Neilson in 1828. David Mushet was born at Dalkeith, near Edinburgh, in 1772.[5] Like other members of his family he was brought up to metal-founding. At the age of nineteen he joined the staff of the Clyde Iron Works, near Glasgow, at a time when the Company had only two blast-furnaces at work. The office of accountant, which he held, precluded him from taking any part in the manufacturing operations of the concern. But being of a speculative and ingenious turn of mind, the remarkable conversions which iron underwent in the process of manufacture very shortly began to occupy his attention. The subject was much discussed by the young men about the works, and they frequently had occasion to refer to Foureroy's well-known book for the purpose of determining various questions of difference which arose among them in the course of their inquiries. The book was, however, in many respects indecisive and unsatisfactory; and, in 1793, when a reduction took place in the Company's staff, and David Mushet was left nearly the sole occupant of the office, he determined to study the subject for himself experimentally, and in the first place to acquire a thorough knowledge of a.s.saying, as the true key to the whole art of iron-making.

He first set up his crucible upon the bridge of the reverberatory furnace used for melting pig-iron, and filled it with a mixture carefully compounded according to the formula of the books; but, notwithstanding the shelter of a brick, placed before it to break the action of the flame, the crucible generally split in two, and not unfrequently melted and disappeared altogether. To obtain better results if possible, he next had recourse to the ordinary smith's fire, carrying on his experiments in the evenings after office-hours. He set his crucible upon the fire on a piece of fire brick, opposite the nozzle of the bellows; covering the whole with c.o.ke, and then exciting the flame by blowing. This mode of operating produced somewhat better results, but still neither the iron nor the cinder obtained resembled the pig or scoria of the blast-furnace, which it was his ambition to imitate. From the irregularity of the results, and the frequent failure of the crucibles, he came to the conclusion that either his furnace, or his mode of fluxing, was in fault, and he looked about him for a more convenient means of pursuing his experiments. A small square furnace had been erected in the works for the purpose of heating the rivets used for the repair of steam-engine boilers; the furnace had for its chimney a cast-iron pipe six or seven inches in diameter and nine feet long. After a few trials with it, he raised the heat to such an extent that the lower end of the pipe was melted off, without producing any very satisfactory results on the experimental crucible, and his operations were again brought to a standstill. A chimney of brick having been subst.i.tuted for the cast-iron pipe, he was, however, enabled to proceed with his trials.

He continued to pursue his experiments in a.s.saying for about two years, during which he had been working entirely after the methods described in books; but, feeling the results still unsatisfactory, he determined to borrow no more from the books, but to work out a system of his own, which should ensure results similar to those produced at the blast-furnace. This he eventually succeeded in effecting by numerous experiments performed in the night; as his time was fully occupied by his office-duties during the day. At length these patient experiments bore their due fruits. David Mushet became the most skilled a.s.sayer at the works; and when a difficulty occurred in smelting a quant.i.ty of new ironstone which had been contracted for, the manager himself resorted to the bookkeeper for advice and information; and the skill and experience which he had gathered during his nightly labours, enabled him readily and satisfactorily to solve the difficulty and suggest a suitable remedy. His reward for this achievement was the permission, which was immediately granted him by the manager, to make use of his own a.s.say-furnace, in which he thenceforward continued his investigations, at the same time that he instructed the manager's son in the art of a.s.saying. This additional experience proved of great benefit to him; and he continued to prosecute his inquiries with much zeal, sometimes devoting entire nights to experiments in a.s.saying, roasting and cementing iron-ores and ironstone, decarbonating cast-iron for steel and bar-iron, and various like operations. His general practice, however, at that time was, to retire between two and three o'clock in the morning, leaving directions with the engine-man to call him at half-past five, so as to be present in the office at six. But these praiseworthy experiments were brought to a sudden end, as thus described by himself:--

"In the midst of my career of investigation," says he,[6] "and without a cause being a.s.signed, I was stopped short. My furnaces, at the order of the manager, were pulled in pieces, and an edict was pa.s.sed that they should never be erected again. Thus terminated my researches at the Clyde Iron Works. It happened at a time when I was interested--and I had been two years previously occupied--in an attempt to convert cast-iron into steel, without fusion, by a process of cementation, which had for its object the dispersion or absorption of the superfluous carbon contained in the cast-iron,--an object which at that time appeared to me of so great importance, that, with the consent of a friend, I erected an a.s.say and cementing Furnace at the distance of about two miles from the Clyde Works. Thither I repaired at night, and sometimes at the breakfast and dinner hours during the day. This plan of operation was persevered in for the whole of one summer, but was found too uncertain and laborious to be continued. At the latter end of the year 1798 I left my chambers, and removed from the Clyde Works to the distance of about a mile, where I constructed several furnaces for a.s.saying and cementing, capable of exciting a greater temperature than any to which I before had access; and thus for nearly two years I continued to carry on my investigations connected with iron and the alloys of the metals.

"Though operating in a retired manner, and holding little communication with others, my views and opinions upon the RATIONALE of iron-making spread over the establishment. I was considered forward in affecting to see and explain matters in a different way from others who were much my seniors, and who were content to be satisfied with old methods of explanation, or with no explanation at all..... Notwithstanding these early reproaches, I have lived to see the nomenclature of my youth furnish a vocabulary of terms in the art of iron-making, which is used by many of the ironmasters of the present day with freedom and effect, in communicating with each other on the subject of their respective manufactures. Prejudices seldom outlive the generation to which they belong, when opposed by a more rational system of explanation. In this respect, Time (as my Lord Bacon says) is the greatest of all innovators.

"In a similar manner, Time operated in my favour in respect to the Black Band Ironstone.[7] The discovery of this was made in 1801, when I was engaged in erecting for myself and partners the Calder Iron Works. Great prejudice was excited against me by the ironmasters and others of that day in presuming to cla.s.s the WILD COALS of the country (as Black Band was called) with ironstone fit and proper for the blast furnace. Yet that discovery has elevated Scotland to a considerable rank among the iron-making nations of Europe, with resources still in store that may be considered inexhaustible. But such are the consolatory effects of Time, that the discoverer of 1801 is no longer considered the intrusive visionary of the laboratory, but the acknowledged benefactor of his country at large, and particularly of an extensive cla.s.s of coal and mine proprietors and iron masters, who have derived, and are still deriving, great wealth from this important discovery; and who, in the spirit of grateful acknowledgment, have p.r.o.nounced it worthy of a crown of gold, or a monumental record on the spot where the discovery was first made.

"At an advanced period of life, such considerations are soothing and satisfactory. Many under similar circ.u.mstances have not, in their own lifetime, had that measure of justice awarded to them by their country to which they were equally ent.i.tled. I accept it, however, as a boon justly due to me, and as an equivalent in some degree for that laborious course of investigation which I had prescribed for myself, and which, in early life, was carried on under circ.u.mstances of personal exposure and inconvenience, which nothing but a frame of iron could have supported. They atone also, in part, for that disappointment sustained in early life by the speculative habits of one partner, and the const.i.tutional nervousness of another, which eventually occasioned my separation from the Calder Iron Works, and lost me the possession of extensive tracts of Black Band iron-stone, which I had secured while the value of the discovery was known only to myself."

Mr. Mushet published the results of his laborious investigations in a series of papers in the Philosophical Magazine,--afterwards reprinted in a collected form in 1840 under the t.i.tle of "Papers on Iron and Steel." These papers are among the most valuable original contributions to the literature of the iron-manufacture that have yet been given to the world. They contain the germs of many inventions and discoveries in iron and steel, some of which were perfected by Mr.

Mushet himself, while others were adopted and worked out by different experimenters. In 1798 some of the leading French chemists were endeavouring to prove by experiment that steel could be made by contact of the diamond with bar-iron in the crucible, the carbon of the diamond being liberated and entering into combination with the iron, forming steel. In the animated controversy which occurred on the subject, Mr.

Mushet's name was brought into considerable notice; one of the subjects of his published experiments having been the conversion of bar-iron into steel in the crucible by contact with regulated proportions of charcoal. The experiments which he made in connection with this controversy, though in themselves unproductive of results, led to the important discovery by Mr. Mushet of the certain fusibility of malleable iron at a suitable temperature.

Among the other important results of Mr. Mushet's lifelong labours, the following may be summarily mentioned: The preparation of steel from bar-iron by a direct process, combining the iron with carbon; the discovery of the beneficial effects of oxide of manganese on iron and steel; the use of oxides of iron in the puddling-furnace in various modes of appliance; the production of pig-iron from the blast-furnace, suitable for puddling, without the intervention of the refinery; and the application of the hot blast to anthracite coal in iron-smelting.

For the process of combining iron with carbon for the production of steel, Mr. Mushet took out a patent in November, 1800; and many years after, when he had discovered the beneficial effects of oxide of manganese on steel, Mr. Josiah Heath founded upon it his celebrated patent for the making of cast-steel, which had the effect of raising the annual production of that metal in Sheffield from 3000 to 100,000 tons. His application of the hot blast to anthracite coal, after a process invented by him and adopted by the Messrs. Hill of the Plymouth Iron Works, South Wales, had the effect of producing savings equal to about 20,000L. a year at those works; and yet, strange to say, Mr.

Mushet himself never received any consideration for his invention.

The discovery of t.i.tanium by Mr. Mushet in the hearth of a blast-furnace in 1794 would now be regarded as a mere isolated fact, inasmuch as t.i.tanium was not placed in the list of recognised metals until Dr. Wollaston, many years later, ascertained its qualities. But in connection with the fact, it may be mentioned that Mr. Mushet's youngest son, Robert, reasoning on the peculiar circ.u.mstances of the discovery in question, of which ample record is left, has founded upon it his t.i.tanium process, which is expected by him eventually to supersede all other methods of manufacturing steel, and to reduce very materially the cost of its production.

While he lived, Mr. Mushet was a leading authority on all matters connected with Iron and Steel, and he contributed largely to the scientific works of his time. Besides his papers in the Philosophical Journal, he wrote the article "Iron" for Napiers Supplement to the Encyclopaedia Britannica; and the articles "Blast Furnace" and "Blowing Machine" for Rees's Cyclopaedia. The two latter articles had a considerable influence on the opposition to the intended tax upon iron in 1807, and were frequently referred to in the discussions on the subject in Parliament. Mr. Mushet died in 1847.

[1] Dr. Roebuck's grandson, John Arthur Roebuck, by a singular coincidence, at present represents Sheffield in the British Parliament.

[2] The carronade was invented by General Robert Melville [Mr. Nasmyth says it was by Miller of Dalswinton], who proposed it for discharging 68 lb, shot with low charges of powder, in order to produce the increased splintering or SMASHING effects which were known to result from such practice. The first piece of the kind was cast at the Carron Foundry, in 1779, and General Melville's family have now in their possession a small model of this gun, with the inscription:--"Gift of the Carron Company to Lieutenant-general Melville, inventor of the smashers and lesser carronades, for solid, ship, sh.e.l.l, and carca.s.s shot, &c. First used against French ships in 1779."

[3] Wilkie the painter once paid him a visit there while in Scotland studying the subject of his "Penny Wedding;" and Dugald Stewart found for him the old farm-house with the cradle-chimney, which he introduced in that picture. But Kinneil House has had its imaginary inhabitants as well as its real ones, the ghost of a Lady Lilburn, once an occupant of the place, still "haunting" some of the unoccupied chambers. Dugald Stewart told Wilkie one night, as he was going to bed, of the unearthly wailings which he himself had heard proceeding from the ancient apartments; but to him at least they had been explained by the door opening out upon the roof being blown in on gusty nights, when a jarring and creaking noise was heard all over the house. One advantage derived from the house being "haunted" was, that the garden was never broken into, and the winter apples and stores were at all times kept safe from depredation in the apartments of the Lady Lilburn.

[4] Dr. Roebuck had been on the brink of great good fortune, but he did not know it. Mr. Ralph Moore, in his "Papers on the Blackband Ironstones" (Glasgow, 1861), observes:--"Strange to say, he was leaving behind him, almost as the roof of one of the seams of coal which he worked, a valuable blackband ironstone, upon which Kinneil Iron Works are now founded. The coal-field continued to be worked until the accidental discovery of the blackband about 1845. The old coal-pits are now used for working the ironstone."

[5] The Mushets are an old Kincardine family; but they were almost extinguished by the plague in the reign of Charles the Second. Their numbers were then reduced to two; one of whom remained at Kincardine, and the other, a clergyman, the Rev. George Mushet, accompanied Montrose as chaplain. He is buried in Kincardine churchyard.

[6] Papers on Iron and Steel. By David Mushet. London, 1840.

[7] This valuable description of iron ore was discovered by Mr. Mushet, as he afterwards informs us (Papers on Iron and Steel, 121), in the year 1801, when crossing the river Calder, in the parish of Old Monkland. Having subjected a specimen which he found in the river-bed to the test of his crucible, he satisfied himself as to its properties, and proceeded to ascertain its geological position and relations. He shortly found that it belonged to the upper part of the coal-formation, and hence he designated it carboniferous ironstone. He prosecuted his researches, and found various rich beds of the mineral distributed throughout the western counties of Scotland. On a.n.a.lysis, it was found to contain a little over 50 per cent. of protoxide of iron. The coaly matter it contained was not its least valuable ingredient; for by the aid of the hot blast it was afterwards found practicable to smelt it almost without any addition of coal. Seams of black band have since been discovered and successfully worked in Edinburghshire, Staffordshire, and North Wales.

CHAPTER IX.

INVENTION OF THE HOT BLAST--JAMES BEAUMONT NEILSON.

"Whilst the exploits of the conqueror and the intrigues of the demagogue are faithfully preserved through a succession of ages, the persevering and un.o.btrusive efforts of genius, developing the best blessings of the Deity to man, are often consigned to oblivion."--David Mushet.

The extraordinary value of the Black Band ironstone was not at first duly recognised, perhaps not even by Mr. Mushet himself. For several years after its discovery by him, its use was confined to the Calder Iron Works, where it was employed in mixture with other ironstones of the argillaceous cla.s.s. It was afterwards partially used at the Clyde Iron Works, but nowhere else, a strong feeling of prejudice being entertained against it on the part of the iron trade generally. It was not until the year 1825 that the Monkland Company used it alone, without any other mixture than the necessary quant.i.ty of limestone for a flux. "The success of this Company," says Mr. Mushet, "soon gave rise to the Gartsherrie and Dundyvan furnaces, in the midst of which progress came the use of raw pit-coal and the Hot Blast--the latter one of the greatest discoveries in metallurgy of the present age, and, above every other process, admirably adapted for smelting the Blackband ironstone." From the introduction of this process the extraordinary development of the iron-manufacture of Scotland may be said to date; and we accordingly propose to devote the present chapter to an account of its meritorious inventor.

James Beaumont Neilson was born at Shettleston, a roadside village about three miles eastward of Glasgow, on the 22nd of June, 1792. His parents belonged to the working cla.s.s. His father's earnings during many laborious years of his life did not exceed sixteen shillings a week. He had been bred to the trade of a mill-wright, and was for some time in the employment of Dr. Roebuck as an engine-wright at his colliery near Boroughstoness. He was next employed in a like capacity by Mr. Beaumont, the mineral-manager of the collieries of Mrs.

Cunningham of Lainshaw, near Irvine in Ayrshire; after which he was appointed engine-wright at Ayr, and subsequently at the Govan Coal Works near Glasgow, where he remained until his death. It was while working at the Irvine Works that he first became acquainted with his future wife, Marion Smith, the daughter of a Renfrewshire bleacher, a woman remarkable through life for her clever, managing, and industrious habits. She had the charge of Mrs. Cunningham's children for some time after the marriage of that lady to Mr. Beaumont, and it was in compliment to her former mistress and her husband that she named her youngest son James Beaumont after the latter.

The boy's education was confined to the common elements of reading, writing, and arithmetic, which he partly acquired at the parish school of Strathbungo near Glasgow, and partly at the Chapel School, as it was called, in the Gorbals at Glasgow. He had finally left school before he was fourteen. Some time before he left, he had been partially set to work, and earned four shillings a week by employing a part of each day in driving a small condensing engine which his father had put up in a neighbouring quarry. After leaving school, he was employed for two years as a gig boy on one of the winding engines at the Govan colliery.

His parents now considered him of fit age to be apprenticed to some special trade, and as Beaumont had much of his father's tastes for mechanical pursuits, it was determined to put him apprentice to a working engineer. His elder brother John was then acting as engineman at Oakbank near Glasgow, and Beaumont was apprenticed under him to learn the trade. John was a person of a studious and serious turn of mind, and had been strongly attracted to follow the example of the brothers Haldane, who were then exciting great interest by their preaching throughout the North; but his father set his face against his son's "preaching at the back o' dikes," as he called it; and so John quietly settled down to his work. The engine which the two brothers managed was a very small one, and the master and apprentice served for engineman and fireman. Here the youth worked for three years, employing his leisure hours in the evenings in remedying the defects of his early education, and endeavouring to acquire a knowledge of English grammar, drawing, and mathematics.

On the expiry of his apprenticeship, Beaumont continued for a time to work under his brother as journeyman at a guinea a week; after which, in 1814, he entered the employment of William Taylor, coal-master at Irvine, and he was appointed engine-wright of the colliery at a salary of from 70L. to 80L. a year. One of the improvements which he introduced in the working of the colliery, while he held that office, was the laying down of an edge railway of cast-iron, in lengths of three feet, from the pit to the harbour of Irvine, a distance of three miles. At the age of 23 he married his first wife, Barbara Montgomerie, an Irvine la.s.s, with a "tocher" of 250L. This little provision was all the more serviceable to him, as his master, Taylor, becoming unfortunate in business, he was suddenly thrown out of employment, and the little fortune enabled the newly-married pair to hold their heads above water till better days came round. They took a humble tenement, consisting of a room and a kitchen, in the Cowcaddens, Glasgow, where their first child was born.

About this time a gas-work, the first in Glasgow, was projected, and the company having been formed, the directors advertised for a superintendent and foreman, to whom they offered a "liberal salary."

Though Beaumont had never seen gaslight before, except at the illumination of his father's colliery office after the Peace of Amiens, which was accomplished in a very simple and original manner, without either condenser, purifier, or gas-holder, and though he knew nothing of the art of gas-making, he had the courage to apply for the situation. He was one of twenty candidates, and the fortunate one; and in August, 1817, we find him appointed foreman of the Glasgow Gasworks, for five years, at the salary of 90L. a year. Before the expiry of his term he was reappointed for six years more, at the advanced salary of 200L., with the status of manager and engineer of the works. His salary was gradually increased to 400L. a year, with a free dwelling-house, until 1847, when, after a faithful service of thirty years, during which he had largely extended the central works, and erected branch works in Tradeston and Partick, he finally resigned the management.

The situation of manager of the Glasgow Gas-works was in many respects well suited for the development of Mr. Neilson's peculiar abilities.

In the first place it afforded him facilities for obtaining theoretical as well as practical knowledge in Chemical Science, of which he was a diligent student at the Andersonian University, as well as of Natural Philosophy and Mathematics in their higher branches. In the next place it gave free scope for his ingenuity in introducing improvements in the manufacture of gas, then in its infancy. He was the first to employ clay retorts; and he introduced sulphate of iron as a self-acting purifier, pa.s.sing the gas through beds of charcoal to remove its oily and tarry elements. The swallow-tail or union jet was also his invention, and it has since come into general use.

While managing the Gas-works, one of Mr. Neilson's labours of love was the establishment and direction by him of a Workmen's Inst.i.tution for mutual improvement. Having been a workman himself, and experienced the disadvantages of an imperfect education in early life, as well as the benefits arising from improved culture in later years, he desired to impart some of these advantages to the workmen in his employment, who consisted chiefly of persons from remote parts of the Highlands or from Ireland. Most of them could not even read, and his princ.i.p.al difficulty consisted in persuading them that it was of any use to learn. For some time they resisted his persuasions to form a Workmen's Inst.i.tution, with a view to the establishment of a library, cla.s.ses, and lectures, urging as a sufficient plea for not joining it, that they could not read, and that books would be of no use to them. At last Mr.

Neilson succeeded, though with considerable difficulty, in inducing fourteen of the workmen to adopt his plan. Each member was to contribute a small sum monthly, to be laid out in books, the Gas Company providing the members with a comfortable room in which they might meet to read and converse in the evenings instead of going to the alehouse. The members were afterwards allowed to take the books home to read, and the room was used for the purpose of conversation on the subjects of the books read by them, and occasionally for lectures delivered by the members themselves on geography, arithmetic, chemistry, and mechanics. Their numbers increased so that the room in which they met became insufficient for their accommodation, when the Gas Company provided them with a new and larger place of meeting, together with a laboratory and workshop. In the former they studied practical chemistry, and in the latter they studied practical mechanics, making for themselves an air pump and an electrifying machine, as well as preparing the various models used in the course of the lectures. The effects on the workmen were eminently beneficial, and the inst.i.tution came to be cited as among the most valuable of its kind in the kingdom.[1]

Mr. Neilson throughout watched carefully over its working, and exerted himself in all ways to promote its usefulness, in which he had the zealous co-operation of the leading workmen themselves, and the grat.i.tude of all. On the opening of the new and enlarged rooms in 1825, we find him delivering an admirable address, which was thought worthy of republication, together with the reply of George Sutherland, one of the workmen, in which Mr. Neilson's exertions as its founder and chief supporter were gratefully and forcibly expressed.[2]

It was during the period of his connection with the Glasgow Gas-works that Mr. Neilson directed his attention to the smelting of iron. His views in regard to the subject were at first somewhat crude, as appears from a paper read by him before the Glasgow Philosophical Society early in 1825. It appears that in the course of the preceding year his attention had been called to the subject by an iron-maker, who asked him if he thought it possible to purify the air blown into the blast furnaces, in like manner as carburetted hydrogen gas was purified. The ironmaster supposed that it was the presence of sulphur in the air that caused blast-furnaces to work irregularly, and to make bad iron in the summer months. Mr. Neilson was of opinion that this was not the true cause, and he was rather disposed to think it attributable to the want of a due proportion of oxygen in summer, when the air was more rarefied, besides containing more aqueous vapour than in winter. He therefore thought the true remedy was in some way or other to throw in a greater proportion of oxygen; and he suggested that, in order to dry the air, it should be pa.s.sed, on its way to the furnace, through two long tunnels containing calcined lime. But further inquiry served to correct his views, and eventually led him to the true theory of blasting.

Shortly after, his attention was directed by Mr. James Ewing to a defect in one of the Muirkirk blast-furnaces, situated about half a mile distant from the blowing-engine, which was found not to work so well as others which were situated close to it. The circ.u.mstances of the case led Mr. Neilson to form the opinion that, as air increases in volume according to temperature, if he were to heat it by pa.s.sing it through a red-hot vessel, its volume would be increased, according to the well-known law, and the blast might thus be enabled to do more duty in the distant furnace. He proceeded to make a series of experiments at the Gas-works, trying the effect of heated air on the illuminating power of gas, by bringing up a stream of it in a tube so as to surround the gas-burner. He found that by this means the combustion of the gas was rendered more intense, and its illuminating power greatly increased. He proceeded to try a similar experiment on a common smith's fire, by blowing the fire with heated air, and the effect was the same; the fire was much more brilliant, and accompanied by an unusually intense degree of heat.

Having obtained such marked results by these small experiments, it naturally occurred to him that a similar increase in intensity of combustion and temperature would attend the application of the process to the blast-furnace on a large scale; but being only a gas-maker, he had the greatest difficulty in persuading any ironmaster to permit him to make the necessary experiment's with blast-furnaces actually at work. Besides, his theory was altogether at variance with the established practice, which was to supply air as cold as possible, the prevailing idea being that the coldness of the air in winter was the cause of the best iron being then produced. Acting on these views, the efforts of the ironmasters had always been directed to the cooling of the blast, and various expedients were devised for the purpose. Thus the regulator was painted white, as being the coolest colour; the air was pa.s.sed over cold water, and in some cases the air pipes were even surrounded by ice, all with the object of keeping the blast cold.

When, therefore, Mr. Neilson proposed entirely to reverse the process, and to employ hot instead of cold blast, the incredulity of the ironmasters may well be imagined. What! Neilson, a mere maker of gas, undertake to instruct practical men in the manufacture of iron! And to suppose that heated air can be used for the purpose! It was presumption in the extreme, or at best the mere visionary idea of a person altogether unacquainted with the subject!

At length, however, Mr. Neilson succeeded in inducing Mr. Charles Macintosh of Crossbasket, and Mr. Colin Dunlop of the Clyde Iron Works, to allow him to make a trial of the hot air process. In the first imperfect attempts the air was heated to little more than 80 degrees Fahrenheit, yet the results were satisfactory, and the scoriae from the furnace evidently contained less iron. He was therefore desirous of trying his plan upon a more extensive scale, with the object, if possible, of thoroughly establishing the soundness of his principle.

In this he was a good deal hampered even by those ironmasters who were his friends, and had promised him the requisite opportunities for making a fair trial of the new process. They strongly objected to his making the necessary alterations in the furnaces, and he seemed to be as far from a satisfactory experiment as ever. In one instance, where he had so far succeeded as to be allowed to heat the blast-main, he asked permission to introduce deflecting plates in the main or to put a bend in the pipe, so as to bring the blast more closely against the heated sides of the pipe, and also increase the area of heating surface, in order to raise the temperature to a higher point; but this was refused, and it was said that if even a bend were put in the pipe the furnace would stop working. These prejudices proved a serious difficulty in the way of our inventor, and several more years pa.s.sed before he was allowed to put a bend in the blast-main. After many years of perseverance, he was, however, at length enabled to work out his plan into a definite shape at the Clyde Iron Works, and its practical value was at once admitted. At the meeting of the Mechanical Engineers' Society held in May, 1859, Mr. Neilson explained that his invention consisted solely in the principle of heating the blast between the engine and the furnace, and was not a.s.sociated with any particular construction of the intermediate heating apparatus. This, he said, was the cause of its success; and in some respects it resembled the invention of his countryman, James Watt, who, in connection with the steam-engine, invented the plan of condensing the steam in a separate vessel, and was successful in maintaining his invention by not limiting it to any particular construction of the condenser. On the same occasion he took the opportunity of acknowledging the firmness with which the English ironmasters had stood by him when attempts were made to deprive him of the benefits of his invention; and to them he acknowledged he was mainly indebted for the successful issue of the severe contests he had to undergo. For there were, of course, certain of the ironmasters, both English and Scotch, supporters of the cause of free trade in others' inventions, who sought to resist the patent, after it had come into general use, and had been recognised as one of the most valuable improvements of modern times.[3]

The patent was secured in 1828 for a term of fourteen years; but, as Mr. Neilson did not himself possess the requisite capital to enable him to perfect the invention, or to defend it if attacked, he found it necessary to invite other gentlemen, able to support him in these respects, to share its profits; retaining for himself only three-tenths of the whole. His partners were Mr. Charles Macintosh, Mr. Colin Dunlop, and Mr. John Wilson of Dundyvan. The charge made by them was only a shilling a ton for all iron produced by the new process; this low rate being fixed in order to ensure the introduction of the patent into general use, as well as to reduce to a minimum the temptations of the ironmasters to infringe it.