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about 31 grains of crystallized carbonate of soda. The following is itscomposition:—
Dry or Anhydrous Nitric Acid .... 11*44Water.88*56
Dilute Nitric Acid.100*00
Strong Liquid Nitric Acid (sesquihydrate) . 14*3Water. 85*7
100*0
Impurities. —The presence of nitrous acid is known by the colour.To detect chlorine or the chlorides, dilute with distilled water, and applynitrate of silver; a white chloride of silver is precipitated. To recognisesulphuric acid, add a solution of chloride of barium to the diluted acid ;a heavy insoluble white sulphate is thrown down. Any fixed impuritiesmay be obtained by evaporating the acid by heat.
Physiological effects. — (a.) On vegetables. —Nitric acid decomposesthe different vegetable tissues to which it may be applied, and givesthem a yellow colour.
(b.) On animals. —Orfila found that 26 grains of commercial nitric acidinjected into the jugular vein, coagulated the blood, and caused death intwo minutes ( Toxicolog. Generate). Yiborg threw a drachm of the acid,diluted with three drachms of water, into the jugular vein of two horses;in two hours they were well: the blood, when drawn, was slightlycoagulated (Wibmer, die Wirkung, &c.) Introduced into the stomach ofdogs it disorganizes this viscus, and causes death in a few hours.
(c.) On man, —On the dead body, M. Tartra has made various experi-ments to determine the appearances produced by the action of nitricacid. Of course this caustic decomposes the organic textures; but thephenomena presented vary according to different circumstances,— as thequantity employed, the presence of other substances, &c.
On the living body, its action of course varies, with the degree ofconcentration or dilution of the acid. In the concentrated form the acidacts as a powerfully corrosive poison, which property it derives in partfrom its affinity for water, but more especially from the facility withwhich it gives out oxygen; so that the appearances caused by its actionon some of the tissues are different from those produced by sulphuricacid. Thus the permanent yellow stain which it communicates to thecuticle is peculiar to it. Iodine, indeed, stains die skin yellow or brown,but a little caustic potash readily removes the stain when recent; whereasthe yellowish stain produced by nitric acid becomes orange on the addi-tion of an alkali or soap. Bromine also stains the skin yellow, but whenrecently produced, the colour may also be removed by potash. The yellowor citron stain communicated to the lining membrane of the tongue,pharynx, &c. by nitric acid is well shewn in Dr. Roupell’s Illustrations ofthe Effects of Poisons. A preparation, presenting similar appearances, ispreserved in the anatomical museum of the London Hospital. Theyellow substance produced by the action of nitric acid on fibrine, wastermed by MM. Fourcroy and Vauquelin the yellow acid: the same subrstance is probably produced by the application of nitric acid to otheranimal principles. This yellow substance is bitter, and is said byBerzelius to consist of yellow, altered fibrin, combined with nitric acidand with malic acid, formed by the action of some nitric acid on thefibrin. Nitric, like sulphuric acid, also chars the animal tissues, andthus, after the ingestion of it, the stomach is sometimes found blackened,
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