Popular Science Monthly/Volume 21/July 1882/Borax in America

From Wikisource
Jump to navigation Jump to search

BORAX IN AMERICA.
By W. O. AYRES, M. D.

BORAX is now well known to occur in very many of the salt-springs in the Coast Mountains of California. But in only two places has it been found in large quantities: these are Borax Lake and Hachinhama (pronounced Hah’-chin-ha’-ma), both being in the immediate vicinity of Clear Lake, about eighty miles north of San Francisco.

Borax Lake is a shallow pool intensely of alkaline water, without inlet or outlet, and of course its extent depends on its reception of rain-water. After an exceptionally wet season it has a length of perhaps a mile and a half, with a depth of eight to ten feet; after an exceptionally dry season, on the contrary, it shows sometimes no water, the muddy bottom being covered with saline incrustations. When it has a length of three fourths of a mile, with a depth of four feet, being perhaps its average condition, the water holds in solution 18·75 grains of solid matter to the ounce—·039 of its own weight. This consists of salts of soda, in the following proportions: Sodium carbonate, ·618; sodium chloride, ·204; sodium biborate, ·178.

But this alkaline water, exceedingly rich as it is in borax, constitutes only a trifling part of the commercial value of the lake. In fact, it has never been turned to account at all in the manufacture of borax, though such use of it is entirely practicable, as the statements to be presently made in relation to Hachinhama will show. The muddy bottom of the lake was found, immediately on its discovery in 1856, to contain borax in crystals, in quantities most astonishing.

These crystals, being tested by various workers in iron and steel, were pronounced equal to the very best of refined borax. They are, in fact, pure biborate of soda, without any other impurities than the mud mechanically entangled with them in their process of crystallization. They correspond to the native borax of other localities, designated as tincal, but yet are decidedly distinct from it. In fact, no such crystals as those of Borax Lake have ever been found in any other locality, and there are several points in connection with their mode of formation, and even their very existence, which are by no means easy of comprehension, as we shall see.

Although the discovery was made, as already stated, in 1856, no practical development of the lake was begun until 1864. From this time it was pressed vigorously until 1868, when it ceased, not from failure of the supply, but simply from mismanagement of the work. The crystals were certainly less abundant at the last than in the earlier workings, but the lake still held and doubtless holds now an amount running to many millions of pounds, if it be not in truth practically inexhaustible.

Their abundunce was such, and the yield was so great, that within the period specified the lake had revolutionized the borax-trade of the United States; in fact, it had accomplished that work before the close of the year 1864. The annual importations since 1855, the earliest date at which the congressional reports enable us to trace them, had varied from $143,218 to $217,944. In 1864 they were suddenly reduced to $8,984, a result due entirely to the working of Borax Lake.

A statement of the manner in which the crude crystals were removed and utilized will bring to our notice the strange peculiarities of their nature, origin, and mode of crystallization.

The mud which constitutes the bottom of the lake is a smooth, even, plastic clay, of unknown depth. It has been bored through thirty feet without showing change in its structure. The upper portion, for four and a half to five feet, holds unnumbered crystals; at that depth they suddenly and abruptly cease. Abundant explorations demonstrated that none were to be found any lower, and the daily working came to recognize the fact as established. The mud below that was saturated with the salts of soda, such as held by the water of the lake, but no distinct crystals existed.

The crystals of borax, in the upper portion, were removed by means of coffer-dams. Each dam consisted of a box, without top or bottom, four feet square and six feet deep, made of thin boiler-iron, suitably stiffened with surrounding bands of heavier iron. These dams, suspended above the water, between large pontoons or floats, were allowed to drop suddenly, whereupon their force of descent, drove the sharp lower edge down through the soft mud and into that which was sufficiently firm and tenacious to resist the impact, and to render thus the iron walls of each a true coffer-dam, from which the entire contents could be easily removed.

The water was first pumped or bailed out, till it became too thick to flow easily, and the remaining mud was lifted in tubs, in true mining style, and thrown into large troughs, where, being subjected to constant agitation in streams of the lake-water, it was washed away, the borax being retained by its superior gravity.

No crystals were found until from twelve to fifteen inches in depth of the most fluid mud had passed away. The mud then began to feel "gritty," as the workmen expressed it, the "grit" consisting of multitudes of most exquisitely perfect minute crystals of borax. These crystals, like all those in the lake, were lying loose, detached from each other, attached to nothing by the base, and consequently perfect at both ends. It is not meant by this that every crystal was absolutely complete in every angle, but that they all had the tendency to the theoretical type, symmetrical at each end (a form which in artificial crystallization we scarcely ever reach, except by accident), and that many of them showed the type in full perfection, such as no model could excel or equal.

With every descending inch through the mud their size increased; the "grit" soon became "sand," in a few inches farther crystals were very manifest to the eye, and shortly a "layer" was reached. It is true that in some places no "layers" occurred, the crystals being scattered at random through the mud. But in most instances when from twenty-four to thirty inches of surface-mud had been removed, and the crystals had attained a length of one fourth to one half an inch, one or more "layers" would be found within the four feet square of the coffer-dam. In these "layers" the crystals were so closely packed as to have no mud intermingled with them; they were nearly as clean as though recently washed in clear water, lying closely stowed and loose, like pebbles on a beach. A "layer might be one to four inches thick and two feet, more or less, in length, surrounded on all sides by mud which held only scattered crystals without any such richness as its enveloped pocket.

Going deeper, the crystals became constantly larger, though less numerous, as the mud grew more dense, until a stratum was reached which was designated "blue clay." In the mud immediately above the blue clay, crystals from one to two inches long were very common, though many of the smaller ones were still intermingled. Here a change in the crystals showed itself, full as well marked as the change in the bed in which they lay. The small crystals were not present; they had never been formed as in the mud above. Instead of them lay imbedded scattered crystals, few in number, but of great size, and having commonly a family look by which they could be recognized. Few of them were as small as two inches in length, and not unfrequently those weighing a pound each were obtained, being perhaps five to seven inches long, by two to four inches wide.

They lay imbedded in the clay, which was so firm that they could be picked out singly, each leaving the sharp mold which it had formed during its slow process of crystallization. They were all within a little more than a foot of the surface of the blue clay, many explorations showing that it was useless to seek for them at a greater depth.

Of the abundance of the crystals within the portion of the lake occupied by them, a space of about forty acres, some idea may be formed from the fact that nine hundred pounds have been gathered from one dam, four feet square. And this by no means represents their full amount, as all the smaller crystals were washed back again into the lake in the process of their separation. At the same time it was remarkably true that the yield was very uneven. In what was known as "rich ground" barren spots constantly occurred, and often almost the entire yield of a dam came from one side or one corner, perhaps only a third or a fourth part of the full area.

The crystals thus obtained had a decidedly green color. The figure introduced is given for the purpose of conveying an idea of the size which the green crystals sometimes attained. It is not an exaggeration. I have seen many which weighed individually as much as the one here delineated. Their proportions were very erratic, but always conforming to the one type.

They were entirely free from the tenacious coating incident to the tincal of other localities; were readily and perfectly soluble in hot water, and in the process of refining by solution and recrystallization yielded-their full weight of transparent borax of the finest quality, less merely the weight of the mud which had been mechanically entangled with them during their growth in a muddy menstruum. The green color disappeared in the refining, not being found either in the deposited mud or the new crystals.

We are prepared now to look at the origin of these salts as held in solution or in crystalline form. If, in a basin of water, more or less shallow, containing a plastic soda-mud in the form of chloride and carbonate, deriving its carbonic acid from one source and its chlorine from another during its deposition, or, subsequently, fissures were opened

PSM V21 D366 Crystal of native borax from borax lake.jpg
Crystal of Native Borax from Borax Lake, Natural Size.

in the subjacent strata, allowing the escape of a limited amount of jets of boracid acid from beneath in vapor, we should have all the conditions required to account for the formation of the borax in the midst of the two more loosely combined salts.

Thus far our way is plain. But whence came the enormous deposition of the green crystals of Borax Lake, their isolation and segregation in perfect crystallized integrity, and their continued preservation; while at the same time, in a solution almost identical in chemical composition, as we shall see, at Hachinhama, and in which often the proportion of borax to a given quantity of water becomes greater, no such crystals exist?

In most instances of salts crystallizing from a solution, the crystals attach themselves by a base to whatever material is adjacent, and when numerous they form a crystalline mass, from which the summits only of the crystals project—a crystal perfect at both extremities, and the sides not being common. And in Borax Lake itself, whenever the water has evaporated to such a degree in a dry season as to form a deposit from excess of strength, it has been an amorphous crust of carbonate, chloride, and borate, with no perfect crystals of either.

But the green crystals are isolated, and in thousands of instances are absolutely perfect, ends and sides. The large ones of the blue clay lie, as we have seen, each in its own mold. The smaller ones above lie often in layers, inches in thickness, hundreds of crystals heaped together as distinct from each other and as separate as pebbles on a beach.

Still, again, comes the strange fact that these crystals have been lying, how long we can not say, but almost certainly for very, very many years (for there is not the slightest evidence to lead us to believe that they are of recent formation), in a solution which makes no approach to saturation, and to whose influence as a solvent they seem totally indifferent.

The water of Borax Lake, when it has a depth in its main extent of five feet, which it often has for very many months and perhaps years in succession, holds in solution about half an ounce of borax to the gallon. During this interval, for four or five months of the summer season, its temperature is at no time lower than 55° to 60° Fahr. But water at that temperature dissolves a little over eight ounces of borax to the gallon. How, then, can the green crystals remain in such a liquid so long without being destroyed?

It may be supposed that the carbonate and chloride, in the complex mixture, render the hold of the borax so slight that, because of their presence, it is ready to separate. In reply to this suggestion comes the statement of the fact that when the same water is concentrated by evaporation to a specific gravity of 12° Beaumé, in which state it holds in solution six ounces of borax to the gallon, no tendency is manifest to the formation of even a single crystal.

Again, it has been suggested that, lying in a muddy menstruum, the movement of particles is so far arrested as to prevent diffusion, the stratum of water immediately surrounding each crystal becoming saturated and remaining unchanged. But this does not in the least account for the commencement of crystallization, which, so far as we can judge, must have been in an exceedingly weak solution. Nor does it perhaps seem possible that such complete seclusion from ascending and descending currents could in any way be secured. The winter rains pour in quite fierce torrents of drainage-water from all sides, often rendering the entire lake decidedly turbid, and of course causing more or less of commotion in every part. And in addition to this is the diffusion of particles, caused by the changes of temperature throughout the year.

In whatever light, therefore, the question is viewed, it is not free from difficulties. And yet at the same time it is but right to recall the fact that these green crystals are in their nature tincal, though such tincal as has never been found elsewhere, and that the crystals of tincal are perhaps in other localities formed subject to the same conditions as here prevail.

We turn now to Hachinhama, the other locality mentioned, as affording the borax-supply of California. This is on the southern side of Clear Lake, about four miles west of Borax Lake, which it closely resembles in its features, though much smaller, being an oval lagoon about four hundred yards in length. We have, as there, a sheet of clear alkaline-water, with a bottom of soft, plastic mud. This mud has been bored to about the same depth as in the explorations at Borax Lake, without its lower limit being reached.

The evidences that the alkaline pool occupies the space of an extinct crater, are more manifest here than at Borax Lake, as the inclosing walls still remain, though abraded on their northern extremity, while on the south they rise abruptly to the great mountain-summit of Conoktai.

The water of Hachinhama holds in solution the salts of soda in the following proportions: Sodium carbonate, ·754; sodium chloride, ·083; sodium biborate, ·163. The mud throughout its entire depth is richly stored with the same salts, but without any development whatever of crystallization of any kind.

After the cessation of work at Borax Lake, in 1868, attention was turned to the resources of Hachinhama. Of course, the style of working must be totally different, for here was no borax ready formed, no green crystals needing simply solution and recrystallization. All that was available was a sheet of water, holding the salts above recorded. The problem, then, was to separate in purity the borax—the only one of sufficient value to be worth the effort—and leave the others.

Borax being the least soluble of the three salts, and at the same time much more soluble in hot water than in cold, it was argued that, were the water of Hachinhama sufficiently concentrated by boiling and then allowed to cool slowly, the borax would crystallize out, leaving the carbonate and chloride in solution.

This is correct in theory, and in laboratory practice the results were entirely satisfactory, but in working large quantities the case was found very different. Concentrated to 20° B., a crop of crystals was deposited which were pure borax, but they were scarcely more than fifty per cent of the borax originally held by the lye thus formed. When, now, this mother-liquor was still further concentrated, no more pure borax separated, but a combined mass of borate and carbonate.

And here was manifested another feature. The amount of borax available depended very largely on the bulk of the solution in which it was allowed to cool. Very small quantities were of course useless in practical working, though the crop from them was satisfactory. Patiently continued trials showed that pans of two to three gallons gave economically the best results. But even here the borax clung so closely to the carbonate as to occasion much difficulty, until the plan was devised of crystallizing them together, and then washing away the carbonate by means of its greater solubility.

This was the plan adopted, and by its use about eighty per cent of the borax originally contained in the Hachinhama water, as pumped into the evaporating-pans, was secured. The extent of the works may be estimated from the fact that about 4,000 of the pans mentioned were in daily use.

But the unassisted lake-water was not long used. Hachinhama, from its shallowness, becomes nearly or quite dry at the close of each summer. As it dries away, the exposed mud is thickly covered with the salts deposited. These were carefully removed for use. The surface thus cleared of its salts began at once to renew its coating, the deposit being speedily replaced by capillary attraction from the stores beneath. In a week, or perhaps more, the surface was ready for sweeping again. The second crop was abundant, it was replaced by a third, and by others in succession, till the advent of the rains (never occurring in that climate till October, or perhaps November) put a stop to their formation.

This process was repeated each year during the occupation of Hachinhama, and, when the lake filled in turn with the winter rains, the alkaline-water bore the same degree of strength consecutively, showing that the stores of supply in the mud beneath gave no evidence of exhaustion.

The salts thus gathered were used by lixiviation to strengthen the lake-water in the evaporating-pans, and thus increase the yield of borax.

The work of refining the borax thus obtained differed in nothing from that employed with the green crystals of Borax Lake—hot solution and crystallization in lead-lined tanks. Hachinhama borax, as placed in the market, was of a grade of excellence never surpassed.

The works were conducted in this manner until the spring of 1872, when a change was introduced in consequence of the discovery that immense deposits of borates existed in Nevada. It was determined to utilize the borate of lime, in the form of ulexite, for the conversion into borax of the carbonate of soda held in the water of Hachinhama.

The ulexite was brought by car-loads from the deserts east of the Sierra Nevada to San Francisco, and thence to Clear Lake, and a great increase in the borax yield of Hachinhama was the result. The process adopted was to saturate, with the ulexite, the boiling lye from the lixiviating tanks, before it had acquired sufficient strength to crystallize on cooling. A double decomposition was thus accomplished, resulting in a thick, milky-looking mixture which was an intensified solution of borax, rendered turbid by the insoluble carbonate of lime, this latter speedily settling and leaving the clear borax-liquor for concentration and crystallization.

Practically, however, this solution was never pure, for here came in again the same fact which had been demonstrated in the first workings at Hachinhama, that the bulk of the liquid in which the action took place had much to do with the chemical union accomplished. In laboratory experiments the work was perfect, and a boiling-heat of only a few minutes formed the full theoretical amount of borax demanded; yet, when dealing with large quantities, this proved impracticable. Although violent boiling was long continued, even for hours, analysis of the lye showed that a certain proportion of the carbonate of soda still remained untouched by the boracic acid, and that, too, when the ulexite employed was in excess of the amount which careful analysis showed was sufficient to saturate the carbonate of soda present. And this excess was a necessity, and the daily working came to recognize it and to act accordingly, for, when the even theoretical quantity only was used, a much larger proportion of the soda remained untouched.

The operations at Hachinhama continued vigorously till 1874, by which time the enormous supply of borax brought into the market from Nevada had reduced the price to so low a point that further production became impossible. Hachinhama supplied all the American borax made from the cessation of work at Borax Lake in 1868 till 1873, and the two localities afforded between 1864 and 1874 all that was ever made in California. The yield of Hachinhama, during the last two years of its running, was something over 5,000 cases of 112 pounds each.

The immense stock crowding upon the market, which has reduced the price of borax to very nearly one fourth of its former rate, is commonly called "California borax," but that is a misnomer, originating in the fact that it has necessarily been shipped from San Francisco; it is exclusively a product of Nevada. It is, in its look, so unlike the ordinary English borax, or that made at Hachinhama, that the contrast is very striking. Still it is practically the same, and has the same working value.

A glance at the map of the State of Nevada shows a large number of dotted spots, individually of no great extent, scattered over the desert regions east of the Sierra Nevada. Most of them are without designation, but a few are marked "Soda Flat," "Salt Marsh," etc. They all have probably a common origin; they are places which long ago (how long we can not tell) were covered with water, since removed by solar evaporation. Each consists of an extent of entirely flat surface of dried mud, sometimes absolutely bare, sometimes covered with saline deposits. It had been known for years that these deposits were both what is there universally called "alkali" (carbonate of soda) and salt. But it was not until 1871 that much attention was drawn to the fact that several of them contained also deposits of borates, though published mention had been made some time earlier that these existed there.

The number of these "marshes," which are marked by borate deposits, it is impossible to state, as so large an extent of that arid region remains as yet very imperfectly known. A sketch of one, however, gives the characteristics of all.

One of the largest is known as the "Columbus Marsh." It is situated in Esmeralda County, about two hundred and fifty miles nearly due east from San Francisco, and about one hundred and sixty miles south of Wadsworth, on the Central Pacific Railroad. The portion last abandoned by the water, and now covered by saline deposits, extends about ten miles from east to west, and three from north to south, with an extension on the south into Fish Lake Valley, forming an arm fifteen miles long by one to three miles wide. Not all parts of this extent are equally rich in salines, neither is the character of the deposits the same at different parts, though it must have formerly been covered with one sheet of water, of presumably a uniform quality or nearly so.

A space of several hundred acres in one part, for instance, is covered with a crust of chloride and carbonate of soda, through which the foot breaks at every step; but the black mud beneath is filled to the depth of six to twelve inches with borate of lime aggregated in nodules, which, when broken open, show a beautiful pearly-white mass of satiny luster. These are the ulexite, and are commonly called "cotton-bolls." They can be picked out by hand like the kernel of a nut, separating clean and clear.

Immediately adjoining the ground thus rich in ulexite is a wide stretch barren of everything, except a little chloride and carbonate. Just beyond this come five or six hundred acres, thickly covered with borate of soda, so little contaminated with sand or anything else as to crystallize out, by simple solution, eighty per cent of its weight in pure borax. Over vast extents of this surface I have seen the crude borax in its granular, semi-crystalline form lying from fifteen to twenty-four inches in depth, while, at the distance of a quarter to half a mile, the borate of lime was in similar abundance. The supply of borax thus indicated is manifestly sufficient to fill all demands, far into the future years, and this refers only to that which is now on the surface; while the experience gained at Hachinhama seems to show quite conclusively that, were all the present store removed, its place would be refilled with a new crop drawn from the inexhaustible resources beneath.

To explain the manner in which these separate deposits have been formed is not easy, though in relation to the two borates the following suggestions may possibly be of some avail: If in a broad, shallow, mud-bottomed lagoon, the sodium of which has already formed its combinations with carbonic acid and chlorine, we imagine the process of evaporation to continue until instead of water there remains merely a muddy mass, so far viscid as to be unable to flow from one point to another, and that into this mass boracic acid is forced from beneath in. jets, here and there, only in limited areas, and not extending beyond them, and if we imagine, still' further, that the supply of boron is not sufficient to displace all the carbon and chlorine, we should have carbonate and chloride existing, intermingled with borate of soda, precisely as we in fact find them, and with a lime-mud we would have the ulexite.

This may perhaps answer for the borates, but a much greater difficulty is encountered when we propose to ourselves the question how the carbonate and the chloride crystallized separately. Over the chief extent they are blended, as they would be left by the evaporation of a lake which held them both in solution. Yet it is also true that, here and there, in areas separated from each other by no elevations whatever, and which have evidently never been separated, but which must have been parts of the same lake, vast beds of pure salt occur; while, perhaps, a quarter or half a mile away, carbonate of soda is lying in equally great quantity. How can these masses have been thus placed? Their bulk demonstrates that in each case quite a considerable depth of solution, even in its most concentrated form, was absolutely necessary. They could not have existed in such juxtaposition and have retained their chemical integrity.

Could the deposits have been formed at different times? There is nothing to indicate it, nor is the difficulty made less by answering this question in the affirmative. The chloride, in a blended solution, would of course be the last to crystallize, yet there is nothing to cause us to believe that over the carbonate-beds a mass of salt was once formed and subsequently removed. Neither can the two salts be crystallized in bulk, from a united solution, by any means with which we are at present acquainted, and left in the state of separate purity, in which countless thousands of tons are now lying on the deserts of Nevada.

The question is as difficult as the one why the mud of Borax Lake is filled with the green crystals, while that of Hachinhama has none. The points concerning the combinations and the crystallizations in the Californian localities, and in those also of Nevada, I can vouch for personally. The facts are as set forth. I have mentioned nothing which I have not myself seen. The questions which are left without answer are certainly worth investigation.