Asbestos.
by Robert H. Jones.
PREFACE.
The substance of the following pages was originally comprised in a series of Letters from Canada to a friend in London, who was desirous of obtaining all the authentic information possible on a subject on which so little appears to be generally known.
The use of Asbestos in the arts and manufactures is now rapidly a.s.suming such large proportions that, it is believed, it will presently be found more difficult to say to what purposes it cannot be applied than to what it can and is.
Under these circ.u.mstances, although much of the information here given is not new, but has been gathered from every available source, it is hoped that the compilation in its present shape may be found acceptable.
R. H. J.
HOTEL VICTORIA, NORTHUMBERLAND AVENUE _April 20, 1888._
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 (?sest??), signifies "indestructible." The French adopt the same derivation, calling it "asbeste" (mineral filamenteux et incombustible). In Germany it is called "steinflachs" (stone-flax); and by the Italians "amianto" (from ??a?t??, pure, incorruptible); so-called because cloth made from it was cleansed by pa.s.sing 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 ma.s.s 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 h.e.l.lish 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 a.s.severating 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 superst.i.tious 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 pa.s.sage 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 pa.s.sing 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-a-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 coa.r.s.e 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, const.i.tuting 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 Genie Civil_ for September, 1883, Canadian asbestos is thus described: "La chrysotile du Canada n"est pas comme l"amiante ordinaire formee d"un paquet de fils d"un blanc verdatre et remplissant des cavites irregulieres: c"est une veritable pierre d"une densite comprise entre 2 et 3, qui se trouve en couches de 3 a 10 centimetres d"epaisseur. Cette pierre possede la propriete de se reduire en fibres perpendiculairement a sa longueur sous un effort tres faible. Ses fibres transversales sont plus resistantes et beaucoup plus facile a filer, a tisser, et a 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 a.s.sumed by several distinct minerals, rather than to designate any particular species. Tremolite, actinolite, and other forms of hornblende and serpentine, pa.s.sing into fibrous varieties, a.s.sume 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 ?????? ?????, 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 coa.r.s.e 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 subst.i.tute 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, pa.s.sing 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 "Pele"s hair." Miss C. F.
Gordon c.u.mming, in her "Fire Fountains of Hawaii," speaks of this as "filaments of stringy brown lava, like spun gla.s.s, 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 gla.s.s is known as Pele"s hair--Rauoho o Pele. It is of a rich olive green or yellowish brown colour--a hint for aesthetic fashions--and is glossy, like the byssus of certain sh.e.l.ls, 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 Pele"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 l.u.s.tre, 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 a.s.sociated. 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 a.s.sociated with ma.s.ses 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 a.s.sociated with ma.s.ses and d.y.k.es 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 quant.i.ties 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 ill.u.s.trates 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 quant.i.ty 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 quant.i.ties 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 coa.r.s.e kind of so-called b.a.s.t.a.r.d 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 a.s.serted 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 quant.i.ties 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, a.s.ses" glue, stalact.i.te," 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 Pharmacopoeia, 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 compet.i.tor. 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 a.s.suming 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.