CHAPTER TWENTY ONE.
TREATS OF TIN-SMELTING AND OTHER MATTERS.
There is something grand in the progress of a mechanical process, fromits commencement to its termination. Especially is this the case in theproduction of metals, nearly every step in the course of which is markedby the hard, unyielding spirit of _vis inertiae_ on the one hand, andthe tremendous power of intelligence, machinery, and manual dexterity onthe other.
Take, for example, the progress of a mass of tin from Botallack.
Watch yonder stalwart miner at work, deep in the bowels of the mine.Slowly, with powerful blows, he bores a hole in the hard rock. Afterone, two, or three hours of incessant toil, it is ready for the powder.It is charged; the match is applied; the man takes shelter behind aprojection; the mass is rent from its ancient bed, and the miner goesoff to lunch while the smoke is clearing away. He returns to his workat length, coughing, and rubbing his eyes, for smoke still lingersthere, unable, it would seem, to find its way out; and no wonder, lostas it is in intricate ramifications at the depth of about one thousandfive hundred feet below the green grass! He finds but a small piece ofore--perhaps it is twice the size of his head, it may be much larger,but, in any case, it is an apparently poor return for the labourexpended. He adds it, however, to the pile at his side, and when thatis sufficiently large fills a little iron wagon, and sends it up "tograss" through the shaft, by means of the iron "kibble." Here the largepieces of ore are broken into smaller ones by a man with a hammer; asfar as the inexperienced eye can distinguish he might be breakingordinary stones to repair the road! These are then taken to the"stamps."
Those who have delicate nerves would do well to keep as far as possiblefrom the stamps of a tin-mine! Enormous hammers or pounders they are,with shanks as well as heads of malleable-iron, each weighing, shank andhead together, seven hundredweight. They are fearful things, thesestamps; iron in spirit as well as in body, for they go on for ever--night and day--wrought by a steam-engine of one hundred horse-power, asenduring as themselves. The stamps are so arranged as to beself-feeders, by means of huge wooden troughs with sloping bottoms, intowhich the ore is thrown in quantities sufficient to keep them constantlyat work without requiring much or constant attendance. Small streams ofwater trickle over the ore to keep it slowly sliding down towards thejaws, where the stamps thunder up and down alternately. A dread powerof pounding have they, truly; and woe be to the toe that should chanceto get beneath them!
The rock they have to deal with is, as we have said, uncommonly hard,and it enters the insatiable mouth of the stamps about the size of aman's fist, on the average, but it comes out from these iron jaws soexceeding fine as to be incapable of thickening the stream ofreddish-yellow water that carries it away. The colour of the stream isthe result of iron, with which the tin is mingled.
The particles of tin are indeed set free by the stamps from solidbondage, but they are so fine as to be scarcely visible, and socommingled with other substances, such as iron, copper, sulphur,etcetera, that a tedious process of separation has yet to be undergonebefore the bright metal can be seen or handled.
At the present time the stream containing it is poured continuously onseveral huge wooden tables. These tables are each slightly raised inthe centre where the stream falls, so that all the water runs off,leaving the various substances it contains deposited on the table, andthese substances are spread over it regularly, while being deposited, byrevolving washers or brushes.
Tin, being the heaviest of all the ingredients contained in the stream,falls at once to the bottom, and is therefore, deposited on the head orcentre of the table; iron, being a shade lighter, is found to lodge in acircle beyond; while all other substances are either spread over theouter rim or washed entirely away. When the tables are full--that is,coated with what appears to be an earthy substance up wards of a foot indepth--the rich tin in the centre is carefully cut out with shovels andplaced in tubs, while the rest is rewashed in order that the tin stillmingled with it may be captured--a process involving much difficulty,for tin is so very little heavier than iron that the lighter particlescan scarcely be separated even after repeated and careful washings.
In old times the tin was collected in large pits, whence it wastransferred to the hands of balmaidens (or mine-girls) to be washed bythem in wooden troughs called "frames," which somewhat resembled abilliard table in form. Indeed, the frames are still largely employedin the mines, but these and the modern table perform exactly the sameoffice--they wash the refuse from the tin.
Being finally cleansed from all its impurities, our mass of tin bearsmore resemblance to brown snuff than to metal. An ignorant man wouldsuppose it to be an ordinary earthy substance, until he took some of itin his hand and felt its weight. It contains, however, comparativelylittle foreign substance. About seventy per cent of it is pure tin, butthis seventy per cent is still locked up in the tight embrace of thirtyper cent, of refuse, from which nothing but intense fire can set itfree.
At this point in the process, our mass of tin leaves the rough hand ofthe miner. In former days it was divided among the shareholders in thisform--each receiving, instead of cash, so many sacks of tin ore,according to the number of his shares or "doles," and carrying it off onmule or horse back from the mine, to be smelted where or by whom hepleased. But whether treated in this way, or, as in the present day,sold by the manager at the market value, it all comes at last to thetin-smelter, whose further proceedings we shall now follow, in companywith Oliver and his friend.
The agent of the smelting company--a stout, intelligent man, whoevidently did "knaw tin"--conducted them first to the furnaces, in theneighbourhood of which were ranged a number of large wooden troughs orbins, all more or less filled with tin ore. The ore got from differentmines, he said, differed in quality, as well as in the percentage of tinwhich it contained. Some had much iron mixed with it, in spite of allthe washings it had undergone; some had a little copper and othersubstances; while some was very pure. By mixing the tin of differentmines, better metal could be procured than by simply smelting theproduce of each mine separately. Pointing to one of the bins, aboutthree yards square, he told them it contained tin worth 1,000 pounds.There was a large quantity of black sand in one of the bins, which, theagent said, was got by the process of "streaming." It is the richestand best kind of tin ore, and used to be procured in large quantities inCornwall--especially in ancient times--being found near the surface,but, as a matter of course, not much of that is to be found now, theland having been turned over three times in search of it. This blacksand is now imported in large quantities from Singapore.
The agent then conducted his visitors to the testing-house, where heshowed them the process of testing the various qualities of tin oreoffered, to the House for sale. First he weighed out twenty parts ofthe ore, which, as we have said, resembled snuff. This, he remarked,contained about five-sixths of pure tin, the remaining one-sixth beingdross. He mixed it with four parts of fine coal dust, or culm, andadded a little borax--these last ingredients being intended to expeditethe smelting process. This compound was put into a crucible, andsubjected to the intense heat of a small furnace for about twentyminutes. At the end of that time, the agent seized the crucible with apair of tongs, poured the metal into an iron mould, and threw away thedross. The little mass of tin thus produced was about four inches long,by half an inch broad, and of a dull bluish-grey colour. It was thenput into an iron ladle and melted, as one would melt lead when about tocast bullets, but it was particularly noteworthy here, that a veryslight heat was required. To extract the metal from the tin ore, afierce heat, long applied, was necessary, but a slight heat, continuedfor a few minutes, sufficed to melt the metal. This remelted metal waspoured into a stone mould, where it lay like a bright little pool ofliquid silver. In a few seconds it solidified, retaining its clearpurity in all its parts.
"That," said the agent, "is tin of the very best quality. We sell itchiefly to dyers, who use it for colour
ing purposes, and for whom no tinbut the best is of any use. I will now show you two other qualities--namely, second and inferior."
He went to a small cupboard as he spoke, and took therefrom a smallpiece of tin which had already gone through the smelting process in thecrucible above described. Melting this in the ladle, he poured it intothe mould, where it lay for a few moments, quite bright and pure, butthe instant it solidified, a slight dimness clouded its centre.
"That," explained the agent, "is caused by a little copper which theyhave failed to extract from the tin. Such tin would not do for thedyers, but it is good for the tin-plate makers, who, by dipping thinsheets of iron into molten tin, produce the well-known tin-plates ofwhich our pot-lids and pans, etcetera, are manufactured. This last bit,gentlemen," he added, taking a third piece of tin from the cupboard, "isour worst quality."
Having melted it, he poured it into the mould, where it assumed a dull,half-solid appearance, as if it were a liquid only half frozen--or, ifyou prefer it, a solid in a half molten state.
"This is only fit to mix with copper and make brass," said the agent,throwing down the mould. "We test the tin ore twice--once to find outthe quantity of metal it contains, and again to ascertain its quality.The latter process you have seen--the former is just the same, with thisdifference, that I am much more careful in weighing, measuring,etcetera. Every particle of dross I would have collected and carefullyseparated from any metal it might contain; the whole should then havebeen reweighed, and its reduction in the smelting process ascertained.Thus, if twenty parts had been the weight of tin ore, the result mightperhaps have been fourteen parts of metal and six parts of dross. Andnow, gentlemen, having explained to you the testing process, if you willfollow me, I will show you the opening of one of our furnaces. Thesmelting-furnace just shows the testing process on a large scale. Intothis furnace, six hours ago," he said, pointing to a brick erection inthe building to which he led them, "we threw a large quantity of tinore, mingled with a certain proportion of culm. It is smelted and readyto be run off now."
Here he gave an order to a sturdy man, who, with brawny arms bared tothe shoulders, stood close at hand. He was begrimed and hairy--like avery Vulcan.
Seizing an iron poker, Vulcan probed the orifice of the furnace, andforthwith there ran out a stream of liquid fire, which was caught in aniron bowl nearly four feet in diameter. The intense heat of this poolcaused the visitors to step back a few paces, and the ruddy glow shonewith a fierce glare on the swart, frowning countenance of Vulcan, whoappeared to take a stern delight in braving it.
Oliver's attention was at once attracted to this man, for he feltconvinced that he had seen his face before, but it was not until he hadtaxed his memory for several minutes that the scene of his adventurewith the smugglers near the Land's End flashed upon him, when he at oncerecognised him as the man named Joe Tonkin, who had threatened his lifein the cavern. From a peculiar look that the man gave him, he saw thathe also was recognised.
Oliver took no further notice of him at the time, however, but turned towatch the flow of the molten tin.
When the iron cauldron was almost full, "slag," or molten refuse beganto flow and cover the top of the metal. The hole was immediatelyplugged up by Vulcan, and the furnace cleared out for the reception ofanother supply of ore. The surface of the tin was now cleared of slag,after which it was ladled into moulds and allowed to cool. This was thefirst process completed; but the tin was still full of impurities, andhad to undergo another melting and stirring in a huge cauldron. Thislatter was a severe and protracted operation, which Vulcan performedwith tremendous power and energy.
In reference to this, it may interest the reader to mention a valuablediscovery which was the result of laziness! A man who was employed in atin-smelting establishment at this laborious work of stirring the moltenmetal in order to purify it, accidentally discovered that a piece ofgreen wood dropped into it had the effect of causing it to bubble as ifit were boiling. To ease himself of some of his toil, he availedhimself of the discovery, and, by stirring the metal with a piece ofgreen wood, caused such a commotion that the end in view wasaccomplished much more effectually and speedily than by the old process.The lazy man's plan, we need scarcely add, is now universally adopted.
The last operation was to run the metal into moulds with the smelter'sname on them, and these ingots, being of portable size, were ready forsale.
While the agent was busily engaged in explaining to Charles Tregarthensome portions of the work, Oliver stepped aside and accosted Joe Tonkin.
"So, friend," he said, with a smile, "it seems that smuggling is notyour only business?"
"No, sur, it ain't," replied Joe, with a grin. "I'm ajack-of-all-trades--a smelter, as you do see, an' a miner _also_, whenit suits me."
"I'm glad to hear it, my man, for it gives you a chance of coming incontact with better men than smugglers--although I'm free to confessthat there _is_ some good among them too. I don't forget that yourcomrade Jim Cuttance hauled me out of the sea. Where is he?"
"Don't knaw, sur," replied Tonkin, with an angry frown; "he and I don'tpull well together. We've parted now."
Oliver glanced at the man, and as he observed his stern, proudexpression of face, and his huge, powerful frame, he came to theconclusion that Cuttance had met a man of equal power and force ofcharacter with himself, and was glad to get rid of him.
"But I have not gi'n up smuggling," added the man, with a smile. "It dopay pretty well, and is more hearty-like than this sort o' thing."
"I'd advise you to fall back on mining," said Oliver. "It is hard work,I know, but it is honest labour, and as far as I have seen, there doesnot appear to be a more free, hearty, and independent race under the sunthan Cornish miners."
Joe Tonkin shook his head and smiled dubiously.
"You do think so, sur, but you haven't tried it. I don't like it. Itdon't suit me, it don't. No, no; there's nothin' like a good boat andthe open sea."
"Things are looking a little better at Botallack just now, Joe," saidOliver, after a pause. "I'd strongly advise you to try it again."
The man remained silent for a few minutes, then he said,--"Well, MrTrembath, I don't mind if I do. I'm tired o' this work, and as my timeis up this very day, I'll go over to-morrow and see 'bout it. There's aman at Newlyn as I've got somethin' to say to; I'll go see him to-night,and then--"
"Come along, Oliver," shouted Tregarthen at that moment; "it's time togo."
Oliver bade Tonkin good-afternoon, and, turning hastily away, followedhis friend.
The two proceeded arm in arm up Market-Jew Street, and turning downtowards the shore, walked briskly along in the direction of thepicturesque fishing village of Newlyn, which lies little more than amile to the westward of Penzance.