106

ELEMENTS OF MATERIA MEDICA.

chloric acid when heated with liquid sulphuric acid. If a watery solu-tion of a chloride, coloured blue by sulphate of indigo, be submitted tothe action of a galvanic battery, the chlorine is evolved at the positivepole {anode) and destroys the colour of the sulphate of indigo in theneighbourhood of that pole.

The chlorates when heated evolve oxygen, and are converted intochlorides. When mixed with strong sulphuric acid they become orangered, and give out the peroxide of chlorine. They do not precipitate thesalts of silver.

Th e perchlorates evolve oxygen, and are converted into chlorides whenheated. They do not become red or give out peroxide of chlorine by theaction of sulphuric acid. The soluble perchlorates precipitate the saltsof potash.

Physiological Effects, [a.) On vegetables. —The germination ofseeds has been said to be promoted by watering them witli a weak solu-tion of chlorine, but the statement is probably erroneous. ( Decand. Phys.Veget. t. ii. p. 632.)

b. On animals generally. —Nysten ( Recherches , p. 140,) injected asmall quantity of chlorine gas into the jugular vein of a dog, and theonly effect was howling. A larger quantity occasioned difficult respi-ration, apparently great agony, and death in three minutes. Thebody was opened four minutes afterwards: the blood was fluid andvenous in the auricles and ventricles, which contained neither gas nor icoagula. On another occasion he threw this gas into the pleura, and |thereby produced inflammation of this membrane and death. Prom f.these experiments, Nysten (op. cit. p. 143) concludes that it is a local )irritant, but has no specific effect on any part of the system.

c. Onman. —Chlorine gas acts as a local irritant. Mr. Wallace (Re-

searches respecting the Medical Powers of Chlorine, particularly inDiseases of the Liver, 1822), tells us, that diluted with air, or aqueousvapour, of 116° F., and applied to the skin, it produces peculiar sensa-tions, similar to those caused by the bite or sting of insects : this effect isaccompanied with copious perspiration, and a determination of blood tothe skin, sometimes attended with an eruption of minute papulae, or evenvesicles. Applied to the skin in a pure form, its action is similar, hutmore energetic. -

If an attempt he made to inspire undiluted chlorine gas, it produces jspasm of the glottis. If the gas he mixed with air, it enters into the |bronchial ramifications, causes a sensation of tightness and suffocation, 9and violent cough. Twice I have suffered most severely from theaccidental inhalation of it; and each time it gave me the sensation of |constriction of the air-tubes, such as might he produced by a spasmodic |condition of the muscular fibres of the bronchial tubes. The attack *usually goes off' in increased secretion from the mucous membrane. When idiluted with a large quantity of air, chlorine may be inhaled withoutexciting cough: it occasions a sensation of warmth in the respiratorypassages, and promotes expectoration.

The irritating effects of chlorine are less powerful on those accustomedto inhale it; as I have repeatedly seen in patients who were using thegas, and which is also shewn by the following statement made by 1 )r.Christison , (Treatise on Poisons, p.736):—“I have been told (says he) ;by a chemical manufacturer at Belfast , that his workmen can work with