The colour of the stomach is generally bright red, but in that of a child, preserved in Guy’s Hospital museum (No. 1798²⁴), the mucous membrane is obliterated, the rugæ destroyed, and a dark-brown stain is a noticeable feature. The stomach is not, however, necessarily affected. In a preparation in the same museum (No. 1798²⁰) the mucous membrane of the stomach of a child who swallowed soap-lees is seen to be almost healthy, but the gullet is much discoloured. The action on the blood is to change it into a gelatinous mass; the blood corpuscles are destroyed, and the whole colour becomes of a dirty blackish-red; the spectroscopic appearances are identical with those already described (see p. 114). The question as to the effects of chronic poisoning by the alkalies or their carbonates may arise. Little or nothing is, however, known of the action of considerable quantities of alkalies taken daily. In a case related by Dr. Tunstall,[124] a man for eighteen years had taken daily 2 ozs. of bicarbonate of soda for the purpose of relieving indigestion. He died suddenly, and the stomach was found extensively diseased; but since the man, before taking the alkali, had complained of pain, &c., it is hardly well, from this one case, to draw any conclusion. [124] _Med. Times_, Nov. 30, 1850, p. 564. It is important to observe that the contents of the stomach may be acid, although the death has been produced by caustic alkali. A child, aged 4, drank from a cup some 14 per cent. soda lye. He vomited frequently, and died in fifteen hours. The stomach contained 80 c.c. of sour-smelling turbid fluid, the reaction of which was acid. There were hæmorrhagic patches in the stomach, and signs of catarrhal inflammation; there was also a similarly inflamed condition of the duodenum.[125] [125] Lesser, _Atlas d. gericht. Med._, Tafel ii. § 114. =Chemical Analysis.=--The tests for potassium or sodium are too well known to need more than enumeration. The intense yellow flame produced when a sodium salt is submitted to a Bunsen flame, and the bright sodium-line at D when viewed by the spectroscope, is a delicate test; while potassium gives a dull red band in the red, and a faint but very distinct line in the violet. Potassium salts are precipitated by tartaric acid, while sodium salts do not yield this precipitate; potassium salts also give a precipitate with platinic chloride insoluble in strong alcohol, while the compound salt with sodium is rapidly dissolved by alcohol or water. This fact is utilised in the separation and estimation of the two alkalies.