Boron

“ The boron was next introduced into a small clay crucible, and intensely heated in a current of hydrogen gas, for the purpose of rendering it more dense and destroying its pyrophoric properties, and was lastly introduced into a combustion tubing, heated to bright redness, and a stream of dry carbonic anhydride passed over it, in order to separate the carbon, finally pure boron being obtained. ”

“ And boron is such a one; its atomic weight is 11, and its compounds are expressed by BX3. Lithium and beryllium are metals; carbon has no metallic properties; boron appears in a free state in several forms which are intermediate between the metals and non-metals. Lithium gives an energetic caustic oxide, beryllium forms a very feeble base; hence one would expect to find that the oxide of boron, B2O3, has still more feeble basic properties and some acid properties, all the more as CO2 and N2O5, which follow after B2O3 in their composition and in the periodic system, are acid oxides. ”

“ Agulhon (1910 a) moistened 2 kgm. pure sand with 500 c.c. nutritive solution for each pot, and boron was added at the rate of 0, 0·1, 1, 10, and 50 mg. boric acid per litre of nutritive solution. Twenty wheat seeds were sown in each pot, and after twelve days the healthy plants in the first four pots were 6–8 cm. high, but those with the maximum amount of boron showed yellowish leaves only 3 cm. long. After three months’ growth the plants were harvested, when those with most boron were found to have died after making about 10 cm. growth. ”

“ Nature gives the following: Hitherto only one compound of boron with sulphur has been known to us, the trisulphide, B2S3, and concerning even that our information has been of the most incomplete description. Berzelius obtained this substance in an impure form by heating boron in sulphur vapor, but the first practical mode of its preparation in a state of tolerable purity was that employed by Wohler and Deville. These chemists prepared it by allowing dry sulphureted hydrogen gas to stream over amorphous boron heated to redness. ”

“ The series of individuals differ among themselves as to their particular needs of nutriment (in the widest sense) and doubtless each group has special need of particular elements, a need that is possibly correlated with morphological and chemical differences. It may well be that boron is one of these elements, associated with certain vital functions in a way as yet unexplained, though it may possibly be found to play some part in the formation of vascular tissues, since it is most abundant in bark and lignified parts. ”

“ It is not volatile below a white heat, and consequently, if heated with salts of more volatile acids, it expels the acid forming oxide from such salts; for example, if potassium sulphate be heated with boron trioxide, sulphur trioxide is liberated and potassium borate formed. It also possesses the power of combining with most metallic oxides at high temperatures, forming borates, which in many cases show characteristic colours. Many organic compounds of boron are known ”

“ As already mentioned above, amorphous boron combines directly with nitrogen at a red heat. If it be heated in a glass tube in a stream of nitric oxide, perfect combustion takes place, 5B + 3NO = B2O3 + 3BN. If the residue be treated with nitric acid, the boric anhydride dissolves, whilst the boron nitride remains [11] as an extremely light white powder, which [68] is sometimes partially crystalline and greasy to the touch, like talc. It is infusible and unchanged, even at the melting-point of nickel. In general, it is remarkable for its great stability with respect to chemical reagents. ”

“ Reaction proceeds rapidly; the mass is stirred with an iron rod, and poured directly into water containing hydrochloric acid. The action is naturally accompanied by the formation of sodium borate, which is dissolved, together with the salt, by the water, whilst the boron settles at the bottom of the vessel as an insoluble powder. It is washed in water, and dried at the ordinary temperature. Magnesium, and even charcoal and phosphorus, are also able to reduce boron from its oxide. ”

“ Boron is prepared by a process similar to that employed to obtain silicium:—Potassium and perfectly dry boracic acid, or, preferably, boro-fluoride of potassium, intimately mixed together, are placed in a glass adopter-tube, and submitted to a low red heat. When cold, the loose cork that fastened its mouth is removed, and hot water poured in, in successive portions, until the whole matter is detached and all its soluble portion dissolved; the liquid is next allowed to settle, and the precipitate washed first with a solution of sal-ammoniac, and afterwards with alcohol ”

“ Similar results were obtained with maize; plants treated with boric acid or potassium borate yielded about 2300 parts boric acid in 100,000 parts dry matter. The general conclusion arrived at by Hotter was that the effect is not so much that of a general poisoning as of a bleaching of parts of the leaf, mere traces of boron being harmless. The cause of injury is local inhibition of assimilation and killing of roots in stronger concentrations. Increase of the strength of boron raises the toxicity until 1/1000 practically inhibits increase in dry substance. ”

“ Boric acid is also a [Pg 430] constituent of certain silicates, such as tourmaline, axinite, and datholite.
The natural borates are used in the preparation of borax, which is largely employed as a preservative agent, for fluxing, and for other purposes.
There is only one series of boron compounds which have any importance. These are the borates in which the trioxide (B2O3) acts the part of a weak acid. The addition of any acid liberates boric acid, which separates out in cold solutions as a crystalline precipitate. ”

“ It was found that sand or soil containing a proportion of boron which is lethal or toxic to a first culture will allow much better growth with a second and subsequent crops. Repeated experiments on the same soil may show the change from a lethal dose to a toxic one, thence to an indifferent and finally to an optimum concentration. Furthermore (Agulhon 1910 b) the very plants may accustom themselves to greater quantities of boron, the increased power of resistance being transmitted. ”

“ It is insoluble in water and unaffected by most reagents, but when heated in a current of steam or boiled for some time with a caustic alkali, slowly decomposes with evolution of ammonia and the formation of boron trioxide or an alkaline borate; it dissolves slowly in hydrofluoric acid.
Borimide B2 (NH) 3 is obtained on long heating of the compound B2S3·6NH2 in a stream of hydrogen, or ammonia gas at 115–120° C. It is a white solid which decomposes on heating into boron nitride and ammonia. Long-continued heating with water also decomposes it slowly. ”

“ Oils, when assisted by heat, will dissolve boracic acid. In naphtha, it is very soluble. With oils, it yields fluid and solid products, which give a green colour to the flame of alcohol. It is not a combustible acid, but only imparts colour to the flame of combustible bodies.
Boron will unite with fluorine, the radical of fluoric acid. When one part of vitrified boracic acid, two of fluate of lime or fluor spar, and twelve of sulphuric acid are distilled, an acid gas will be obtained, called fluo-boric gas. For the properties of boron, consult Thenard's Traité de Chimie. ”

“ Boric acid is less harmful to the growth of higher plants than are the compounds of copper, zinc, and arsenic. Evidence exists that below a certain limit of concentration boron exercises a favourable influence upon plant growth, encouraging the formation of stronger roots and shoots. This stimulation is more strongly marked with some species than with others, peas responding more readily than barley to the action of boric acid. ”

“ Now, we have a lot of boron deficiency here in the East, and in areas in which we have trouble with growing vegetables, like cauliflower that has a hollow stem, or beets or turnips that split and crack, or where we have so-called drouth spot or internal corking in apples, you can be sure that you can't grow a Persian walnut, because the boron requirement alone is many, many times that of an apple or of most vegetables. ”

“ Agulhon (1910 c) found that the toxic doses of boric acid in soil cultures approached those in nutritive solutions rather than in sand cultures, a phenomenon that he attributed to the fact that the boric acid was fixed by the soil, probably as insoluble borate of calcium, so that the surface concentration obtained with sand cultures was avoided. He found that the ash of plants grown with excess of boron contained more than the normal amount of boron, while the weight of ash per 100 dry matter was also increased. ”

“ In the center are the alumina and boron oxide. These regulate the behavior of the glaze in the fire. They make it viscous or sluggish as it melts and prevent a too rapid flow. The alumina is infusible, the boron is fusible, but boron cannot be used in a raw glaze for reasons to be presently explained. At the right stands the silica, the dominating factor with which all the other ingredients [144] combine, and which controls the behavior of the whole as regards the fitting of the glaze to the body. ”

“ The boron contained in solution in the salt lakes has very probably been supplied by hot springs and solfataras of volcanic origin, such as those which at the present day charge the waters of the lagoons in Tuscany with boric acid. The deposits formed by evaporation from these lakes and marshes or salines, are mixtures of borates, various alkaline salts (sodium carbonate, sulphate, chloride) , gypsum, &c. In the mud of the lakes and in the surrounding marshy soil fine isolated crystals of borax are frequently found. For example, crystals up to 7 in. ”

“ It occurs in several allotropic forms, is very hard when crystallized, and is rather inactive toward reagents. It forms a hydride, BH3, and combines directly with the elements of the chlorine family. Boron fluoride (BF3) is very similar to silicon fluoride in its mode of formation and chemical properties.
Boric oxide (B2O3) . Boron forms one well-known oxide, B2O3, called boric anhydride. It is formed as a glassy mass by heating boric acid to a high temperature. It absorbs water very readily, uniting with it to form boric acid again ”

“ It may be more simply prepared by heating anhydrous borax with potassium ferrocyanide, or by heating borax with ammonium chloride. For this purpose one part of borax is intimately mixed with two parts of dry ammonium chloride, and the mixture heated in a platinum crucible. A porous mass is formed, which after crushing and treating with water and hydrochloric acid, leaves boron nitride. Boron fluoride, BF, is known, corresponding to BN; this body was obtained by Besson and Moissan (1891) . ”

“ Recent developments indicate that the metal, boron, may play an important part in the metallurgy of various metals. It has been used in making very pure copper castings for electrical purposes, in aluminum bronzes, and in hardening aluminum castings; and an alloy, ferroboron, has been shown experimentally to act on steel somewhat like ferrovanadium.
The bulk of the world's borax comes from the Western Hemisphere, the United States and Chile being the two principal producers. ”

“ Terrestrial boron-containing minerals are either calcium or sodium berates. A calcium borate may be converted to a sodium borate by treatment with Na2CO3, yielding borax and CaCO3 which precipitates out of solution. (Calcium carbonate may be recycled by roasting to obtain CaO and CO2, from the latter of which elemental carbon can be recovered.) ”

“ The difficulty is that most boron compounds themselves are poisonous to human tissues, and only small concentrations can be tolerated in the blood. Efforts have been made, with some success, to synthesize new boron compounds that have the greatest possible degree of selective absorption by the tumors. Both organic and inorganic compounds have been tried, and the degree of selectivity has been shown to be much greater for some than for others. ”

“ It has, however, an intense affinity for boron, and will even go through a carbon crucible to unite with it. It is not combined with O in the air; but the two form a mixture (page 86) , of which N makes up four-fifths, its use being to dilute the O. What would be the effect, in case of a fire, if air were pure O? What effect on the human system?
Growing plants need a great deal of N, but they are incapable of making use of that in the air, on account of the chemical inactivity of the element. Their supply comes from compounds in earth, water, and air. ”

“ Some borates too are volatile at high temperatures, and minerals containing boron (especially tourmaline) are very common in tin veins. Also since ore deposits of this character are found nearly invariably in granite or in the rocks which have been invaded by granite there is good reason to hold that fluoric and boric gases were important agents in the production of tin veins. It is not necessary, however, to believe that all the materials which are found in these veins were introduced as vapours, for as the temperature sank currents of hot water would follow which would fill up any cavities. ”

“ The Patent Borax, which consists of a combination of boron and sodium, acts in a marvellous manner as an arrester of decay, and as such is useful for the preservation of meat, milk, butter, and all articles of animal food liable to taint and decay, especially in hot weather. When infused in small quantities in water, it preserves and softens it for drinking, cooking, washing, and all household purposes; it whitens linen and cleanses it far better than soda, it kills harmful insect life, though perfectly harmless to human beings and domestic animals ”