CHLORATES  , the metallic salts of chloric

acid; they are all solids, soluble in water, the least soluble being the potassium salt . They may be prepared by dissolving or suspending a metallic oxide or hydroxide in water and saturating the solution with chlorine; by double decomposition; or by neutralizing a solution of chloric acid by a metallic oxide, hydroxide or carbonate . They are all decomposed on heating, with evolution of oxygen; and in contact with concentrated sulphuric acid with liberation of chlorine peroxide . The most important is potassium chlorate, KCIO3, which was obtained in 1786 by C . L . Berthollet by the action of chlorine on caustic potash, and this method was at first used for its manufacture . The modern process consists in the electrolysis of a hot solution of potassium chloride, or, preferably, the formation of sodium chlorate by the electrolytic method and its subsequent decomposition by potassium chloride . (See ALKALI MANUFACTURE.) Potassium chlorate crystallizes in large white tablets, of a bright lustre . It melts without decomposition, and begins to give off oxygen at about 370° C . According to F . L . Teed (Prot .

Chem .

Soc., 1886, p . 141), the decomposition of potassium chlorate by heat is not at all simple, the quantities of chloride and perchlorate produced depending on the temperature . A very gentle heating gives decomposition approximating to the equation of 22KC103=14KC104+8KC1+502, whilst on a more rapid heating the quantities correspond more nearly to 10KC1Os=UKCIO4+4KCI+302 . The decomposition is renderedmore easy and regular by mixing the salt with powdered manganese dioxide . The salt finds application in the preparation of oxygen, in the manufacture of matches, for pyrotechnic purposes, and in medicine . Sodium chlorate, NaClOa, is prepared by the electrolytic process; by passing chlorine into milk of lime and decomposing the calcium chlorate formed by sodium sulphate; or by the action of chlorine on sodium carbonate at low temperature (not above 35° C.) . It is much more soluble in water than the potassium salt . Potassium chlorate is very valuable in medicine . Given in large doses it causes rapid and characteristic poisoning, with alterations in the blood and rapid degeneration of nearly all the internal organs; but in small doses—5 to 15 grains—it partly undergoes reduction in the blood and tissues, the chloride being formed and oxygen being supplied to the body-cells in nascent form . Its special uses are in ulceration of the mouth or tongue (ulcerative stomatitis), tonsillitis and pharyngitis . For these conditions it is administered in the form of a lozenge, but may also be swallowed in solution, as it is excreted by the saliva and so reaches the diseased surface .

Its remarkable efficacy in healing ulcers of the mouth—for which it is the specific—has been ascribed to a decomposition effected by the carbonic acid which is given off from these ulcers . This releases chloric acid, which, being an extremely powerful antiseptic, kills the bacteria to which the ulcers are due .