Boric acid

“ 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. ”

“ Generally speaking, the evidence goes to prove that boric acid is toxic down to a concentration of about 500 parts in 25 million. It is difficult to get a true control with which to make comparisons as the plants without boric acid are encumbered with the slime on their roots, which naturally interferes with normal growth, while the plants in the presence of boric acid have the unfair advantage due to the probable antiseptic action of the boron. ”

“ It is generally conceded that as far as regards digestion neither borax nor boric acid have any specific influence, but when considerable quantities are present the alkalinity of the former or slight acidity of the latter may be of some effect. In a similar way they may act as mild irritant poisons, occasioning diarrhœa. With continued use most observers find a loss of weight, which seems to be due to loss of fat in the body, and this may occur, without any symptoms of ill health, when small quantities of borax or boric acid are ingested daily. ”

“ The supply of borax is, however, mainly derived from the boric acid of Tuscany, which is fused in a reverberatory furnace with half its weight of sodium carbonate, and the mass after cooling is extracted with warm water. An alternative method is to dissolve sodium carbonate in lead-lined steam-heated pans, and add the boric acid gradually; the solution then being concentrated until the borax crystallizes. Borax is also prepared from the naturally occurring calcium borate, which is mixed in a finely divided condition with the requisite quantity of soda ash ”

“ The influence of a little sulphuric acid in the wool would be in the direction of neutralising some of the ammonia or soda, and shellac, if dissolved in the alkalis, would be to some extent precipitated on the fibre, unless the alkali, soda or ammonia, were present in sufficient excess to neutralise that sulphuric acid and to leave a sufficient balance to keep the shellac in solution. Borax, which is a borate of soda, would be so acted on by the sulphuric acid that some boric acid would be set free, the sulphuric acid robbing some of that borax of its soda. ”

“ If too much hydrochloric acid has been employed a dirty brownish-red color is obtained, which interferes with the color due to the presence of {358} boric acid. When a drop of household ammonia is added to the colored turmeric paper, it is turned a dark green, almost black color, if boric acid is present. If the reddish color, however, was caused by the use of too much hydrochloric acid this green color does not form.
Caution.—The corrosive nature of hydrochloric acid must not be forgotten. It must not be allowed to touch the flesh, clothes, or any metal. ”

“ Some preservatives have been conclusively shown to be injurious when used for long periods, although their occasional use may be attended with no bad effect. Boric acid is pretty definitely condemned, after experiments on living subjects. ”

“ The salt crystallizes in masses of small, hard, colourless, trans- parent, rhombic prisms. It is precipitated when an excess of a potassium salt is added to a solution of tartaric acid, but it dissolves in mineral acids, and in alkalis and alkaline carbonates. Solutions of boric acid or borax dissolve it freely, forming soluble cream of tartar, which is a white powder permanent in the air when made with the acid, but deliquescent when borax is employed. Its slight solu- bility in alcohol explains why it is deposited by wines as they mature. ”

“ Archangeli (1885) placed seedlings of maize, white lupins, Vicia sativa and Triticum vulgare in solutions of boric acid varying in concentration from 1–·05%, with controls in spring water. In the latter case the development was normal, with 1% boric acid the plants were killed, while it was found that the weaker the solution (within the indicated limits) the stronger the root and shoot growth.
Hotter (1890) stated that it was known that 1/20,000 boric acid by weight was harmful to soy beans in nutritive solutions. ”

“ Carbolic acid has the tendency of hardening the glue-stock and imparting its odor to the glue, and among other antiseptics, formaldehyde and boric acid have been recommended for the purpose of preventing putrefaction for a reasonable time. Formaldehyde in weak solution (1 part in 10,000 to 100,000 parts water) has been found beneficial. In this small quantity it does not harden the stock nor affect the subsequent boiling, as it is dissipated by the heat. Boric acid and its preparations, notwithstanding their low antiseptic power, are much in favor. ”

“ Boric acid in aqueous or glycerine solutions, and borax (biborate of soda) are sometimes used, but care is necessary in employing these substances, as any excess is liable to decompose the soap.
The addition of cocoa-nut oil is unsatisfactory, the great objection being that complete saponification is difficult to ensure, and, further, there is always the liability of rancidity developing. Stearic and oleic acids are more suitable for the purpose, but oleic acid has the disadvantage that oleates are very liable to go rancid. ”

“ Among these are included alum, borax and boric acid. Every physician has used them. To say that a wafer consists of alum, borax and boric acid inspires but little awe. But there is something much more mysterious and impressive in declaring that a wafer “consists of an astringent and antiseptic base, in which are incorporated certain medicaments which both locally and after absorption, contribute to the astringent, antiphlogistic, depletive, soothing and healing action of the product.” This gives the impression that some powerful and almost incomprehensible factors are at work. ”

“ 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. ”

“ By another English patented process the meat is soaked during from twenty-four to thirty-six hours in a solution of 150 grammes of boric acid, 300 grammes of borax, 155 grammes of common salt, and 53 grammes of saltpeter, which had been previously dissolved in two litres of water, after which it is packed in casks. A practicable method of preparing meat for long transportation is to expose it to a current of refrigerated air till it is stiffened, then sprinkle powdered borax upon it, and put it in a refrigerator-car. ”

“ Analysis of specimens purchased from different sources in the open market were made under our direction. The reports of the chemists show that Tyree’s antiseptic powder contains no borax, or mere traces only, and that it contains no alum, or mere traces only. Instead, the analyses show that boric acid and zinc sulphate are the essential constituents. The amounts of carbolic acid, thymol, menthol, 124etc., contained in the powder, if present, were far below the quantities indicated by the formula. The presence of glycerin could not be demonstrated, and if present the amount must be very small. ”

“ Its preservative action, that is, its potency, is very slight in comparison with most other preservatives; its potential injuriousness to man must be proportionately small. It is practically without interference upon salivary, peptic or tryptic digestion, unless given in large quantities. Experiments made by F. W. Tunnicliffe and R. Rosenheim upon children showed that neither boric acid nor borax, administered in doses of from 15 to 23 grains per diem, exerted any influence upon proteid metabolism or upon the assimilation of phosphatized materials. ”

“ 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. ”

“ 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. ”

“ The atomic weight of boron has been determined by estimating the water content of pure borax (J. Berzelius) , also by conversion of anhydrous borax into sodium chloride (W. Ramsay and E. Aston) and from analysis of the bromide and chloride (Sainte-Claire Deville) ; the values obtained ranging from 10.73 to 11.04. Boron can be estimated by precipitation as potassium fluoborate, which is insoluble in a mixture of potassium acetate and alcohol. For this purpose only boric acid or its potassium salt must be present ”

“ While the wrapper of the “large size” trade package claims that Germiletum contains 3⁄4 minims Formalin (Formalin is a proprietary name for a 40 per cent. formaldehyd solution) the label on the bottle claims only 1⁄2 minim. Again, while the composition expressed in chemical symbols asserts that “H3BO3” (boric acid) is a constituent of Germiletum, the “formula” which follows it states that Germiletum has an alkaline reaction; hence it cannot contain much boric acid. ”

“ When fetor exists, as during the detachment of patches of exudation, antiseptic and detergent sprays may be employed. Solutions of borax, boric acid, carbolic acid, potassium chlorate, potassium permanganate, etc. are appropriate. In some individuals, especially strumous and tuberculous subjects, there is a constitutional proclivity to chronicity or to the recurrence of the peculiar manifestations. More active measures will be required in these cases. Locally, frequent application of the dilute acids (i.e. every day or two) affords the most satisfactory results. ”

“ As the most commonly used chemical preservative is boric acid, free or in the form of borax, which is extensively employed in butter, cream, ham, sausages, potted meats, cured butter, cream, ham, sausages, potted meats, cured fish, and sometimes in jams and preserved fruit, the arguments for and against its employment deserve more detailed attention. It cannot be looked upon in the light of common adulteration because, in any case, the quantity used is but an inconsiderable fraction, and the cost of it is generally greater than that of the food itself. ”

“ Borax and boric acid are effective, cheap, odorless, and tasteless when mixed with food, and are much used. The testimony is conflicting as to the effect of the continued and frequent use of these preservatives upon the health of consumers. There are some falsifications which the public have long tolerated and people are careless of, as those of mustard, which is now sometimes hard to find strong enough to make a plaster of. ”

“ 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. ”

“ Does boron stimulate higher plants?
Of recent years a few investigators have thrown out hints as to the stimulant action exerted by boron compounds on plants. Roxas indicated that M/100,000 (M = molecular weight) of boric acid exercised a favourable action on rice. Nakamura (1903) tested the point by means of pot cultures. Peas and spinach plants were grown in soil which received 1 and 5 mg. borax per kgm. With peas the 1 mg. exerted evident stimulant action, as determined by the increase in height of the shoot over that of the control, 5 mg. seeming to be slightly depressant in action. ”

“ 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 ”