CONTENTS.
| PAGE | |
| Introductory | [5-8] |
| Asbestos at the American Exhibition | [9, 10] |
| Where Found | [12-15] |
| Italian and Canadian Asbestos compared | [16-18] |
| Where Used | [18] |
| The Asbestos of Italy | [19-24] |
| Mining for Asbestos | [24-29] |
| Asbestos Mines of Canada— | |
| The Thetford Group | [29-36] |
| The Coleraine Group | [36-42] |
| Broughton | [42-46] |
| Danville | [46] |
| South Ham | [47-50] |
| Wolfestown | [50] |
| Uses to which Asbestos is Applied | [55-72] |
| Index | [75, 76] |
[ASBESTOS.]
One of Nature's most marvellous productions, asbestos is a physical paradox. It has been called a mineralogical vegetable; it is both fibrous and crystalline, elastic yet brittle; a floating stone, which can be as readily carded, spun, and woven into tissue as cotton or the finest silk.
Called by geologists "asbestus" (the termination in os being the adjective form of the word), the name of the mineral in its Greek form as commonly used (ἄσβεστος), signifies "indestructible." The French adopt the same derivation, calling it "asbeste" (minèral filamenteux et incombustible). In Germany it is called "steinflachs" (stone-flax); and by the Italians "amianto" (from ἀμίαντος, pure, incorruptible); so-called because cloth made from it was cleansed by passing it through fire. Charlemagne, we are told, having a cloth made of this material in his possession, one day after dinner astonished his rude warrior guests by throwing it in the fire, and then withdrawing it cleansed and unconsumed.
As a modern pendent to this well-known legend, the following is current in Quebec. A labouring man, who had left the old country to seek a better fortune in the Dominion, found employment at once on arrival in one of the many lumber yards on the St. Lawrence, where his energy and activity, supplemented by great bodily strength, soon secured for him a good position. It so happened, however, that one evening, on returning from their daily toil to their common apartment, some of his fellow-workmen saw him deliberately throw himself into a seat, kick off his boots, and then pull off his socks, and having opened the door of the stove, coolly fling them in on to the mass of burning wood. Possibly no particular notice would have been taken of this, judged as a mere act of folly and waste on the part of the new-comer; but when, almost immediately afterwards, they saw him open the stove door again, take out the apparently blazing socks, and, after giving them a shake, proceed just as deliberately to draw them on to his feet again, that was a trifle too much! Human nature could not stand that. Consequently the horrified spectators, having for a moment looked on aghast, fled precipitately from the room. To them the facts were clear enough. This, they said, was no human being like themselves; such hellish practices could have but one origin. If not the devil himself, this man certainly could be no other than one of his emissaries. So off they went in a body to the manager and demanded his instant dismissal, loudly asseverating that they would no longer eat, drink, or work in company with such a monster. Enquiry being at once set on foot, it turned out that some time before leaving England the man had worked at an asbestos factory, where he had learned to appreciate the valuable properties of this mineral; and being of an ingenious turn of mind, he had managed to procure some of the fiberized material and therewith knit himself a pair of socks, which he was accustomed to cleanse in the manner described. He was, as has been said, an unusually good workman, consequently his employers had no wish to part with him. Explanation and expostulation, however, were all in vain; nothing could remove the horrible impression that his conduct had made upon the minds of his superstitious fellow-workmen; go he must and did, nor could the tumult be in any way allayed until he had been dismissed from his work and had left the yard.
Leaving this digression, however, it may be said that the peculiar properties of the mineral were known long before Charlemagne's time. The ancients, who believed it to be a plant, made a cere-cloth of it, in which they were accustomed to enwrap the bodies which were to be burned on the funeral pyre, so that the ashes might be retained, separate and intact, for preservation in the family urn, an aperture being left in the cloth to allow a free passage for the flames. How they succeeded in weaving this cloth is now unknown. It has been suggested that its accomplishment was effected by weaving the fibres along with those of flax, and then passing the whole through a furnace to burn out the flax.
The lamps used by the vestal virgins are also said to have been furnished with asbestos wicks, so that the modern adaptation of it to this purpose is only another exemplification of the truth of Solomon's saying that "there is nothing new under the sun."
The mineral has been variously described. In general terms it may be said to be a fibrous variety of serpentine, closely allied to the hornblende family of minerals, the Canadian variety of which is called by mineralogists "chrysotile." In the local vernacular of the mining districts this is "pierre-à-coton" (cotton-stone), perhaps as expressive a term as can be found.
The ore takes a variety of forms; much of it (especially that found in the States) is of a coarse woody character, of but little value for mercantile purposes.
Sir William Logan, in his "Geology of Canada," says that foliated and fibrous varieties of serpentine are common in veins of the ophiolites of the Silurian series, constituting the varieties which have been described under the various names of baltimorite, marmolite, picrolite, and chrysotile. The true asbestos, however, he says, is a fibrous variety of tremolite or hornblende.
In Le Génie Civil for September, 1883, Canadian asbestos is thus described: "La chrysotile du Canada n'est pas comme l'amiante ordinaire formée d'un paquet de fils d'un blanc verdâtre et remplissant des cavités irrégulières: c'est une véritable pierre d'une densité comprise entre 2 et 3, qui se trouve en couches de 3 à 10 centimètres d'épaisseur. Cette pierre possède la propriété de se reduire en fibres perpendiculairement à sa longueur sous un effort très faible. Ses fibres transversales sont plus résistantes et beaucoup plus facile à filer, à tisser, et à feutrer que l'amiante ordinaire." This is as good a description of chrysotile as can be found anywhere.
Until the discovery of the Canadian mines, the variety here spoken of as amiante (amianthus), was esteemed the most rare and delicate kind, on account of its beautifully white, flexible, long, and delicately laid fibres. This variety is generally found buried in the centre of the older crystalline rocks in the Pyrenees, the Alps of Dauphiny, on Mount St. Gothard, in North America, in the serpentines of Sweden, the Ural Mountains, Silesia, and New South Wales. The most beautiful specimens, such as are preserved in museums and mineralogical collections, have mostly been brought from Tarantaise in Savoy, or from Corsica.[1] In this latter place it is said to be so abundant that, its mercantile value being unknown, it has often been used, instead of tow, as a material for packing.
In a handbook published by the Dominion Government in 1882 (before the discovery of the mines of chrysotile) on the mineral resources of Canada, it is said that—
"What is commercially known as asbestos is really a term used to denote a peculiar fibrous form assumed by several distinct minerals, rather than to designate any particular species. Tremolite, actinolite, and other forms of hornblende and serpentine, passing into fibrous varieties, assume the name of asbestos, and the 'Geology of Canada' does not give the mineral as a distinct one, but recognizes it under these different headings. As yet comparatively little asbestos has been found in Canada."
This is sufficient to show how small was the interest, even so recently as that, attaching to this substance in the very country which was so soon to find it taking important rank amongst her natural productions.
That singularly beautiful mineral termed "crocidolite," which displays such sheens and radiances of gold and bronze and green as give it the appearance of satin changed into stone, is nothing more than compressed asbestos. The derivation of its name is not happy. It is said to be from κροκος λιθος, simply crocus-coloured or yellow stone. This is doubtless its general colour, but the finest crocidolite is anything but yellow.
Having heard that there were some fine specimens of asbestos on view at the recent exhibition of the United States products at Earl's Court, I made a journey there specially to see them. In this, however, I was disappointed. There was but one small tray of so-called asbestos (amphibole) on view; and this was of a coarse woody character, very similar in appearance to a sample I had had sent to me recently from California. It was, moreover, of a very poor colour and certainly not of the kind that would readily find a market. I found there, however, a piece of unmistakable chrysotile, grouped amongst a miscellaneous lot of American minerals. The exhibitor at once told me, in reply to my questions, that this was not an American product at all, but that it was a "vegetable matter" found in Canada. He evidently did not know much about it, and said it was not asbestos at all. It was not by any means a fine specimen: it had somewhat the appearance of ordinary Thetford No. 1, though differing slightly in colour. I could get no further information about it, except that it had come from near Ottawa.
At this exhibition I found a splendid display of crocidolite, the sight of which well repaid the visit. I secured a good specimen, but found, on enquiry, that like all the superior qualities of this mineral, it had been brought from Griqualand (South Africa). The sample I secured was of the kind that in the States is called "Tiger-eye," as I presume, from its general tawny-coloured streaky brilliancy. The exhibitor said it was a silicate of iron occurring in asbestos-like fibres. It is of an exceedingly hard, densely compact nature; from its hardness difficult to work, but susceptible of a very high polish. A few years ago it was thought to be a precious stone and accordingly commanded a high price, but recent discoveries of large deposits considerably reduced its value. It is used for a variety of ornamental purposes, for which, from its extreme natural beauty, it is peculiarly adapted. The grain is very fine and in its rough state the fibres are singularly distinct.
There is another very singular substance worth alluding to here, which is often put forward as a substitute for asbestos, and which is said by the manufacturers to be fireproof, frost-proof, vermin-proof, sound-proof, indestructible, and odourless. This is a good deal to say, but is in a great measure true. It is largely used in the United Slates, especially for insulating and other purposes of a like kind. I mean the artificially manufactured material called "Mineral or Slag Wool," which is made from the refuse of the furnaces at ironworks, by, it is said, passing jets of steam through molten slag. This material is manufactured on a somewhat extensive scale by the Western Mineral Wool Company, of Cleveland, Ohio. There is no doubt it is a very useful substance for many of the purposes for which it is recommended, but it can scarcely be expected to compete to any material extent with asbestos from its total want of elasticity and lubricity. Even the finest quality on being crushed between the fingers has a harsh, gritty, metallic feeling, very different from the silky, springy, and greasy feel of the natural fibre.
In connection with this manufactured article, a very curious natural production is called to mind, the origin of which is somewhat similar though brought about by natural causes. I refer to the product of the lava-beds of Hawaii, called by the natives "Pélé's hair." Miss C. F. Gordon Cumming, in her "Fire Fountains of Hawaii," speaks of this as "filaments of stringy brown lava, like spun glass, which lie scattered here and there, having been caught by the wind (when thrown up) in mid-air in a state of perfect fusion, forming fine lava drops, a rain of liquid rock, and so drawn out in silky threads like fine silky hair."
"In fact, this filmy, finely spun glass is known as Pélé's hair—Rauoho o Pélé. It is of a rich olive green or yellowish brown colour—a hint for æsthetic fashions—and is glossy, like the byssus of certain shells, but very brittle to handle. Sometimes when the great fire-fountains toss their spray so high that it flies above the level of the cliffs, the breeze catches it sportively and carries it far away over the island; and the birds line their nests with this silky volcanic hair. Sometimes you can collect handfuls clinging to the rocks to which it has drifted, generally with a pear-shaped drop attached to it." This, it is evident, would crumble and break off short in the fingers, and the mineral wool when handled has just the same gritty brittle feeling one can imagine Pélé's hair to have.
Returning to asbestos, however, its formation or actual origin is at present unknown. In its pure state it is as heavy as the rock in which it is found, so closely are its fine elastic crystalline fibres compressed together. These have a beautiful silky lustre, varying in colour from pure white to a dusky grey or green, sometimes of a yellowish green; the direction of the fibres being transverse to the walls of the vein. The essential point in which it differs from any other known mineral consists in its being at once fibrous and textile. Its quality is determined by the greater or less proportion of silicious or gritty matter with which its fibres are associated. When crushed out from the rock, these fibres, which vie in delicacy with the finest flax or the most beautiful silk, can be corded, spun, and woven into cloth in precisely the same way as any other textile fibre.
Of good quality it is only found in serpentine. One instance of its having been found in quartz is mentioned; but, even in that case we are told, when six feet of the superficial quartz rock had been blasted away, the inevitable serpentine was found cropping through.
According to Mr. Ells,[2] the serpentines in which it is found are intimately associated with masses of dioritic or doloritic rocks, of which rocks certain varieties, rich in olivine or some allied mineral, the serpentine is, in many cases, an alteration product. They are frequently associated with masses and dykes of whitish rocks, which are often composed entirely of quartz and felspar, but occasionally with a mixture of black mica, forming a granitoid rock. They occur generally not far from the axes of certain anticlinals which exist in the group of rocks called by Sir William Logan the "altered Quebec group."
For centuries asbestos was regarded merely as a mineral curiosity. Indeed, it is only within the last few years that it has developed into a valuable article of commerce, the first modern experiments in the use of it practically extending no farther back than 1850.
Its uses in the arts and manufactures are of a very important character, and now that it is clearly demonstrated that a fairly abundant supply can be obtained at a moderate cost, there seems no reasonable limit to be put to the demand, new uses for it being continually found. These will, of course, rapidly increase as its value becomes more clearly and widely known.
It is found in most parts of the world, but in only a few places of a sufficiently valuable kind or in quantities large enough to give it any commercial value. The main sources of supply at present are Canada and Italy.
A good deal has, at times, been found in Russia; and I remember an incident which occurred a few years ago at some extensive ironworks in that country, with which I was at the time connected, which amusingly illustrates how little was then known there of the nature and properties of the mineral. The iron ore, in the district referred to, is found in bunches or nodules, near the surface of the ground; and in order to get it, the peasants dig out pits about seven or eight feet in depth, and then burrow, rabbit-like, into the surrounding earth in all directions below. When all the ore is got out from one spot, they dig another pit further afield, and so they go on until the particular patch of ground they are working on is exhausted. On the occasion referred to, some of our men, in their burrowing, threw out a considerable quantity of asbestos. They had not the slightest idea what it was. In fact, they knew nothing at all about it, except that it was not what they were in search of; and, consequently, as it obstructed their work, they threw it all out in a heap near the piles of ore. Presently, one of the foremen or overlookers saw it, and wanted to know what all that rubbish had been put there for. "Here," said he, to some of the men, "just clear up all that mess at once, and fling it into the furnace, and get rid of it." And this was immediately done, with what result you may imagine.
Recently, however, it is said that enormous quantities of asbestos have been found in Russia, although I cannot learn that any use is made of it there at present. Its mercantile value must of course depend on its quality and distance from market. I have had a great number of specimens sent me, but they mostly turn out to be a coarse kind of so-called bastard asbestos, which would not pay for extracting. Now, however, we are told that from Orenburg to Ekaterinburg the country is thickly dotted with asbestos deposits, while near the Verkin Tagil ironworks there is a hill called Sholkovaya Gora, or Hill of Silk, which it is asserted is entirely composed of asbestos. The ore here is also said to be of the best white quality, well adapted for all the most important purposes to which asbestos is applied. I should much like to see a specimen of this; its value could be easily determined on inspection. In the Gorobtagsdat district of Perm, again, there are said to be large deposits cropping out above the surface, and also that enormous quantities could be had there for nothing, as at this moment it possesses no value in the Ural region. I imagine it would be found of considerable value if a practical man were sent out to see to its fiberization on the spot, when it might be compressed, packed, and exported in the same way as cotton. There can, however, be little doubt that if its quality is as good as it is represented to be, it will very soon be utilized, and will then form a very important addition to the vast mineral wealth of that region.
As might be expected, asbestos is also found in China, but, as a matter of course, the use to which it is put there is one we should little dream of here. For instance, in the translation of a Chinese medical book by Dr. Hobson, of the London Medical Mission, asbestos is seen to figure (of all places in the world) under the head of tonics, in company with such heterogeneous substances as "dried spotted lizard, silkworm moth, human milk, parasite of the mulberry tree, asses' glue, stalactite," and a few more surprising things. Perhaps it may be just as well for us that we are not yet educated up to so fine a point as that, and that consequently the mineral we are speaking of does not yet find a place in the British Pharmacopœia, but is left to exhibit its apparently more natural properties in the arts and manufactures.
A correspondent of The Financial News, writing from Barberton in January, 1888, says that at Komali Fields, fifty miles from that place, asbestos has just been found, but that it was as yet too soon to discuss the merits of the find.
In sending you an account of the Canadian asbestos industry, you will scarcely expect me to give you any very detailed information about its Italian competitor. Any account of the one, however, would necessarily be so incomplete without some mention of the other, that I will do the best I can with the little information I have been enabled to obtain on the subject of the Italian mines.
Experiments with the view of utilizing asbestos in Italy appear to have been first successfully carried on in 1850 by the Chevalier Aldini, of Milan, and others, mainly with the object of turning the mineral to account in the manufacture of asbestos cloth. The Chevalier had a complete suit made of it—cap, gloves, tunic, and stockings—for the purpose of testing its protective powers for firemen; and of this I shall have something to say presently.[3] But it was not until twenty years after this that any success was attained in the manufacture of asbestos millboard and paper, the commercial value of which is now assuming such large proportions.
About the same time the manufacture of asbestos into packings for piston glands was successfully accomplished in America; and some two years afterwards a company, calling itself "The Patent Asbestos Manufacturing Company, Limited," was formed in Glasgow for the purpose of making piston packings according to this American invention. In 1880 this Glasgow Company united its business with that of Messrs. Furse Brothers and Co., of Rome, asbestos manufacturers, as well as with that of the Italo-English Pure Asbestos Company, and, when the amalgamation was complete, the new Company, taking the name of "The United Asbestos Company, Limited," became possessed of nearly the whole of the known Italian mines, and, consequently, of a practical monopoly of the trade in asbestos from that country.
Italian differs very materially from Canadian asbestos, not only in appearance, but in formation also, as well as in the mode of extraction. The two are, in fact, entirely separate and distinct kinds of the same mineral; notwithstanding which their intrinsic qualities are practically the same, and the uses to which they are put are almost identical.
An extraordinary specimen of Italian asbestos, obtained from one of the mines of the United Asbestos Company, situate in the Valtellina Valley, is in the possession of that company, and is no doubt the finest piece of asbestos ever brought from Italy, whether as regards strength or fineness of fibre. Any one interested in the matter would, I have no doubt, be readily permitted to inspect this natural curiosity, on application to Mr. Boyd, the courteous manager of the company, in Queen Victoria Street.
Just about this time (1880) Canadian asbestos, also, was being much talked about and sought after; and it is therefore perhaps scarcely to be wondered at that the company which first began to work the mineral in Italy on a large scale, and which, at great expense and trouble, had managed to secure the whole of the Italian mines, and so become possessed, as they supposed, of a monopoly of the trade, should have viewed with jealousy the rapid progress made in public estimation by the Canadian ore when once it was introduced to the market.
It is not my purpose, however, to enter on the vexed question of the relative merits of the two varieties, which would be altogether out of place in a letter of this kind. But I think we may safely conclude that both possess undeniably good qualities, and that there is an ample field for both, inasmuch as the peculiar properties which render one kind unsuitable for some particular purpose are often precisely those which best adapt it for another. Each variety will assuredly make its own way and take its proper place in public estimation as further experiments and greater experience in the use of it shall bring its special value more prominently to light.
Ample proof has been given of the valuable qualities of Italian asbestos; and if any proof were needed of the intrinsic value of its Canadian competitor, nothing more would be required than to point to such houses as that of John Bell & Son, of London; of Wertheim, of Frankfort; or to the Johns Manufacturing Company, or the Chalmers-Spence Company, of New York, whose world-renowned manufactures are made of Canadian asbestos alone.
The essential characteristics of both sorts are alike in this respect, that they are absolutely indestructible by fire, or even when exposed to the action of any known acid; the Canadian variety possessing in addition, in a very high degree, that strange peculiarity (which is also claimed for one of the Italian sorts), and is common also to plumbago and soapstone, of being a self-lubricator. Good Canadian fibre is known at once by its soft, greasy, soapy feeling; and one of the leading New York firms claims for its products, made entirely of Canadian asbestos, that they will resist even the flame of the blowpipe; and further asserts that this mineral transcends all previously thought-of materials for fireproofing, in that it is not only absolutely indestructible by fire, but that its power of resistance cannot be worn away or diminished by lapse of time or hard usage, as invariably happens in the case of such applications as tungstate of soda.
Regarding its use, Germany is a very large consumer. In France the consumption is not so great, although manufacturers in that country are now beginning to bestir themselves, especially in regard to some very valuable kinds of paper, which they are making entirely out of Canadian fibre; and Paris has now set the world an example by the adoption of the Chevalier Aldini's plan of clothing firemen in a dress of asbestos cloth.
America, however, is the country where the most rapid strides are being made in the development of every branch of this new industry, and there also the Canadian fibre alone is used.
A considerable quantity of it is made use of in England, in the manufacture of some valuable kinds of packing for engineering work, millboards, felts, lubricants, paint, and the like; but in England we lack in some degree the readiness which is found on the other side of the ocean, in the adaptation of new materials and new methods of work.
Whether it be that Englishmen are influenced by climatic or other causes, certain it is that they are slow to adopt new systems, to cultivate novel ideas, or to move out of old grooves. Consequently, when new materials, or even novel applications of those long used, are suggested, they ponder over them, hesitate, and weigh the chances, and in so doing not infrequently let slip valuable opportunities; whilst the keener and more enterprising American, once he sees the drift of the new matter, will, to use his own expression, "catch hold" at once. It by no means follows, however, that this is the fault of the manufacturers alone; they have naturally to gauge the requirements of their customers, and prefer to limit their make to what they know they can sell.
The finer kinds of asbestos, the strong fibres of which are of a pure white colour and of a fine silky texture, being at the same time free from silicic acid or metallic oxide, are comparatively rare; and, on account of their lubricating qualities, are especially valuable. This particular kind, I am told, is at the present time only to be found in Canada and some parts of the States. Whether this statement is correct or not, I am not in a position to say; but that it is found in Canada I know, for I have there personally witnessed the blasting out of many hundreds of tons. In the Dominion it is invariably obtained from hard rock somewhat difficult to work.
In an interesting paper on Italian asbestos, to be found in the "Journal of the Society of Arts" for April, 1886, to which I have been indebted for a good deal of information respecting the Italian mines, I find a very singular statement given as the result of long observation by the employés of the United Company in Italy. It is there said that "if asbestos be found on the surface of a rock exposed either to the south or south-west, the product is generally fairly abundant and of good quality. If exposed to the east there is fine quality, but very small quantity; whilst if exposed to the north the quantity is plentiful but dry and hard, and on entering the rock all traces of it are lost."
Whether this be at all consistent with Canadian experience I cannot say. The lie of the ground and the course of the veins being so different, it is quite possible the theory may have no applicability at all to Canadian mining. But it is certainly suggestive and interesting, and I will cause inquiry in this direction to be set on foot at once.
In the same paper I find the following given as analyses of the two varieties. The first is stated to be by Professor Barff, but by whom the latter was made does not appear. According to these there would be little doubt which was the most valuable for general manufacturing purposes, but as there is nothing to show what kind of Canadian ore was submitted for analysis, or by whom the analysis was made, you must take it as an analysis only, quantum valeat.
Three distinct kinds of asbestos are said to be found in Italy, viz., Grey, Flossy, and Powdery. The grey is a long, fibrous variety, possessing, in addition to strength, the much-prized saponaceous quality; and this is mostly found in the two Alpine valleys of Valtellina and d'Aosta. The flossy, which has a smooth, silky appearance, but a dry feeling when touched, is found and worked in part of the chain of mountains which bound the valley leading from Susa to Turin, and at an elevation of about 8,000 feet above the sea level. This is the kind which is mostly used in the manufacture of gas stoves. It is commonly found in thicker seams than the grey, lying mostly in a horizontal direction, but dipping rapidly as the rock is entered. The third is a powdery kind, which, while possessing all the heat-resisting properties of the two others, crumbles in the hand when touched. This variety is found in the same range of mountains as that last mentioned, but at a much lower level; it appears to have been first brought to light by a landslip exposing to view a seam of it three feet wide. When first seen it is said to have had a pasty consistency, but on exposure to the air it dried and crumbled into powder.
Italian ore, generally speaking, is won by running driftways, or tunnelling into the face of the rock. In Canada the mineral is got out by open quarrywork, no tunnelling there being possible. The serpentine rock in which the asbestos or chrysotile is there found is so split and seamed in every conceivable direction by the veins and stringers that if tunnelling were attempted the first blast would inevitably bring the whole superincumbent mass down about your ears. You might as well attempt to tunnel through loose sand or gravel. In other words, the relative difference in the two modes of winning the ore appears to be that the Italian asbestos may be said to be won by tunnelling into the face of the rock; whilst the Canadian chrysotile is found in veins, running, it is true, with the greatest irregularity, but yet with a distinctly perpendicular declension. The Italian variety, again, seems frequently to be found, or the seams to end, in pockets, some of which have been known to contain a ton or a ton and a half of asbestos, after exhaustion of which all appearance of its presence ceased. The Canadian ore, on the other hand, generally runs in veins and seams, which almost invariably improve both in quantity and quality the lower you go down, but where or how it ends has never yet been discovered.
It may possibly be, however, that the more correct way to put this would be the very opposite of what I have just stated; because if you stand and face the rock when laid bare in any of the Canadian mines and trace the downward course and increasing strength of the veins, it would really seem as if this strange mineral substance, at some former time, when in a state of violent ebullition, had striven energetically to force an outlet into the upper air, splitting the overlying rock in all directions in its passage upward from below; and that, as it gradually cooled off and expended its force, the rifts in the rock, which now form the veins, became narrower and narrower, until, when the surface of the ground was at last reached it had only just sufficient energy left to bubble over through the cracks, where it then cooled off and hardened into thin lava-like ridges. These ridges are to be seen in all directions in the asbestos districts of Canada, wherever the peculiar yellowish-looking stone forming the upper crust of the asbestos-bearing rocks is found. And notwithstanding the plainly visible evidence that these rocks, from centuries of exposure to the elements, have been worn away on the upper surface until they have assumed a rounded, water-washed, boulder-like shape, the narrow ridges spoken of have apparently always remained in the same state, alike indestructible and undisturbed.
If you will imagine to yourself the mountain masses of almost perpendicular rock, which contain the horizontally-lying seams frequently found in Italy, to be thrown backward and downward so as to lie face uppermost, and so that you could walk on the face, you will get a rough idea of the lie of the veins in the Canadian serpentine. And possibly on further exploration the analogy would be still further borne out by these veins being found to terminate in reservoirs or pockets, just as it has been said is usually found to be the case in Italy. No one has yet gone far enough down to test the depth of the veins in any Canadian mine. It will no doubt presently be done. All that would be required would be to bore until the next series was reached. The experiment, if expensive, would be both valuable and instructive, especially bearing in mind the well-known fact in Canadian mining that the deeper you follow the veins into the ground the better the quality of the cotton becomes.
There is one more point of distinction between the two kinds, and that is in the surface indications, which may possibly be due to atmospheric influences. In Italian exploration the prospector is not guided by any hard lines or ridges on the rock surface of the ground, as in Canada. On the contrary, he finds cracks in the perpendicular face of the rock filled with a white powdery substance which, when the surface is broken away, is said to assume a leathery appearance, after which, when further entry is made, the true asbestos is found.
Thus, it will be seen that there is not only a considerable difference between the two sorts of asbestos which supply the demands of the market, but that the mode of winning it is also different; as are, moreover, the natural indications which guide the explorer in his search after the mineral.