The doctors use four general classes of medicines to combat the disturbances that are caused by the four elements. These are chiefly derived from the vegetable kingdom, and from such kinds as are indigenous to their country. A small proportion of their medicines are imported from China, and purchased from Chinese apothecaries. Barks, roots, leaves, chips, orchard-fruit, and herbs, constitute the great bulk of their _materia medica_. Next to these they employ articles of medicine belonging to the animal kingdom, such as bones, teeth, sea-shells, fish-skins, snake-skins, urine, eyes of birds, cattle, cats, and the bile of snakes and of numerous other animals. Lastly, but less frequently, they employ articles from the mineral kingdom, such as stones, saltpetre, borax, lead, antimony, sulphate of copper, table-salt, sulphate of magnesia, and, very rarely, mercury. Besides the above, aloes and gamboge, and a few other gums and resins, are occasionally used. The dependence of Siamese physicians, in waging war with disease, is more upon a large combination of ingredients in a prescription than upon the power of any one or two of the same. Hence they often have scores of components in a single dose. One hundred and seventy-four ingredients were counted by a missionary in one prescription, which was ordered to be taken in three doses. They employ their vegetable combinations chiefly in the state of decoction or infusion. A common way of speaking of the quantity of medicine which a person has taken is to say that he has swallowed three, five, or more pots of it—each pot containing from two to four quarts. And a common way of paying the doctor is by the potful, from 30 to 60 cents each. The form of pills is esteemed a more select mode of administering their vegetable medicines; but as these are more expensive and troublesome to prepare, patients are charged more highly for them. Medical practitioners in Siam are all, with rare exceptions, self-taught, or mere empirics. If a man wishes to try his fortune as a doctor he reads a native medical manuscript or two upon some kind of disease, and quickly ventures to practise, following the directions of the book. If he happens to be successful in a case, or nature has cured the person in spite of his treatment, he trumpets his triumph abroad, and asserts that he has rescued his patient from death; and the Siamese, who, with all their native cunning, are easily gulled in medical matters, credit his reports, and his fame is assured. The ignorance of the physicians is safeguarded by the fact that all the cures that take place in connection with the use of their physic are attributed to it, and all failures to cure are supposed to result from the malicious interference of evil spirits, wizards, witches, or something else beyond the power of human skill to contend against.