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district they are covered by small muddy lakes (lagoni). The soffioni contain a small quantity of boric acid (usually less than ca I %), together with a certain amount of ammoniacal vapours. In See also:

order to obtain the acid, a See also:

SERIES (a Latin word from serere, to join)

series of basins is constructed over the vents, and so arranged as to permit of the passage of water through them by See also:

GRAVITATION (from Lat. gravis, heavy)

gravitation. Water is led into the highest See also:

basin and by the action of the heated gases is soon brought into a See also:

state of ebullition; after remaining in this basin for about a See also:

day, it is run off into the second one and is treated there in a similar manner. The operation is carried on through the entire series, until the liquor in the last basin contains about 2 % of boric acid.

It is then run into settling tanks, from which it next passes into the evaporating pans, which are shallow See also:

lead-lined pans heated by the gases of the soffioni. These pans are worked on a continuous See also:

SYSTEM

system, the liquor in the first being concentrated and run off into a second, and so on, until it is sufficiently concentrated to crystallize. The crystals are purified by recrystallization from water. Artificial soffioni are sometimes prepared by See also:

BORING

boring through the See also:

rock until the fissures are reached, and the water so obtained is occasionally sufficiently impregnated with boric acid to be evaporated directly. Boric acid is also obtained from boronatrocalcite by treatment with sulphuric acid, followed by the evaporation of the See also:

SOLUTION (from Lat. solvere, to loosen, dissolve)

solution so obtained. The See also:

RESIDUE (through the French, from the Lat. residuum, a remainder, from residere, to remain)

residue is then heated in a current of superheated steam, in which the boric acid volatilizes and distils over. It may also be obtained by the decomposition of boracite with hot hydrochloric acid. In small quantities, it may be prepared by the addition of concentrated sulphuric acid to a See also:

COLD (in O. Eng. cald and ceald, a word coming ultimately from a root cognate with the Lat. gelu, gelidus, and common in the Teutonic languages, which usually have two distinct forms for the substantive and the adjective, cf. Ger. Kolte, kalt, Dutch koude

cold saturated solution of borax. Na2B4O2 +H2SO4+5H20 = Na2SO4+4H3B03• Boric acid crystallizes from water in See also:

white nacreous laminae belonging to the triclinic system; it is difficultly soluble in cold water, but dissolves readily in hot water. It is one of the " weak " acids, its See also:

DISSOCIATION

dissociation See also:

CONSTANT, BENJAMIN (1845-1902)

constant being only 0.03169 (J. See also:

Walker, Jour. of Chem. See also:

Soc., 1900, lxxvii.

5), and consequently its salts are appreciably hydrolysed in aqueous solution. The free acid turns See also:

BLUE (common in different forms to most European languages)

blue See also:

LITMUS (apparently a corruption of lacmus, Dutch lacmoes, lac, lac, and moes, pulp, due to association with " lit," an obsolete word for dye, colour; the Ger. equivalent is Lac/emus, Fr tournesol)

litmus to a See also:

CLARET (from the Fr. vin claret, mod. clairet, wine of a light clear colour, from Lat. clarus, clear)

claret See also:

COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour. Its action upon See also:

TURMERIC (from Fr. terre Write, turmeric, Lat. terra merita, deserved, i.e. excellent earth; Skeat suggests that it is a barbarous corruption, perhaps of Arabic karkam, kurkum, saffron or curcuma)

turmeric is characteristic; a turmeric See also:

paper moistened with a solution of boric acid turns See also:

brown, the colour becoming much darker as the paper dries; while the addition of See also:

SODIUM [symbol Na, from Lat. natrium; atomic weight 23.00 (0=16)]

sodium or See also:

POTASSIUM [symbol K (from kalium), atomic weight 39.114 0=16)]

potassium hydroxide turns it almost See also:

black. Boric acid is easily, soluble in See also:

ALCOHOL

alcohol, and if the vapour of the solution be inflamed it See also:

burns with a characteristic vivid See also:

green colour. The acid on being heated to 1oo° C. loses water and is converted into metaboric acid, HBO3 ; at 140° C., pyroboric acid, H2B402, is produced ; at still higher temperatures, boron trioxide is formed. The salts of the normal or orthoboric acid in all See also:

PROBABILITY (Lat. probabilis, probable or credible)

probability do not exist; See also:

META

meta-boric acid, however, forms several well-defined salts which are readily converted, even by See also:

CARBON (symbol C, atomic weight 12)

carbon dioxide, into salts of pyroboric acid. That orthoboric acid is a tribasic acid is shown by the formation of See also:

ETHYL

ethyl orthoborate on esterification, the vapour See also:

DENSITY (Lat. densus, thick)

density of which corresponds to the molecular See also:

formula B(OC2H5)3; the molecular formula of the acid must consequently be B(OH)3 or H3BO3. The metallic borates are generally obtained in the hydrated See also:

CONDITION (Lat. condicio, from condicere, to agree upon, arrange; not connected with conditio, from condere, conditum, to put together)

condition, and with the exception of those of the See also:

ALKALI

alkali metals, are insoluble in water. The most important of the borates is sodium pyroborate or borax (q.v.). Borax and boracic acid are feeble but useful See also:

ANTISEPTICS (Gr. avrl, against, and 6177rrnKor, putrefactive)

antiseptics. Hence they may be used to preserve See also:

food-substances, such as See also:

MILK (0. Eng. meoluc; from a common Indo-European root, cf. Lat. mulgere, Gr. ?t dXyetv)

milk and See also:

BUTTER (Lat. butyrum, Gr. 0obrvpov, apparently connected with $ous, cow, and rvpbs, cheese, but, according to the New English Dictionary, perhaps of Scythian origin)

butter (see See also:

ADULTERATION). In See also:

MEDICINE

medicine boracic acid is used in solution to relieve itching, but its chief use is as a mild antiseptic to impregnate See also:

LINT (in M. Eng. linnet, probably through Fr. linette, from lin, the flax-plant; cf. " line ")

lint or See also:

cotton-See also:

WOOL, WORSTED AND WOOLLEN MANUFACTURES

wool.

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