1. From a peculiar idiosyncrasy, some persons are unable to take the smallest dose of Mercury without its producing serious, and occasionally fatal consequences: for example, Dr. Christison quotes a case, in which exfoliation of the jaw, and death, resulted from the external application of 3iij. of Ung. Hydrarg.; and in another, the same effects were produced by two grains of Calomel. Before commencing its use, therefore, the practitioner is bound to make strict inquiry, whether, on any former occasion, it has disagreed. If such be the case, Mercury in any form should be avoided.

2. The action of all mercurial preparations is promoted by a previous use of blood-letting, emetics, and an antiphlogistic diet.

3. The age, sex, temperament, and general health of the patient, influence greatly the action of Mercury. Children are salivated with great difficulty. Drs. Bennett, Clarke. Evanson, and Maunsell,§ state that they have never seen a child under two years of age, in whom unequivocal salivation was established. Aged persons are also extremely difficult to bring under the influence of Mercury. Prof. Graves accounts for this circumstance in both cases (children and old persons) by the undeveloped state of the parotid glands in the former, and by their shrunken and atrophied state in the latter.

4. Persons in robust health are generally very slightly susceptible to the action of Mercury; and the state of health in the same person at the time of taking the medicine greatly modifies its effects; thus a woman who will resist its influence for a considerable period when in health, will be salivated by a single dose when suffering from anaemia.

6. Those who pursue their outdoor avocations, and at the same time live freely, are with difficulty brought under its influence; and Dr. Macgregor states that it is almost impossible to salivate a person who smokes largely.

6. In some acute inflammations, particularly in that of the brain, it is with great difficulty that ptyalism can be established; and Dr. Graves || supports his own opinion by those of Marshall, Annesley, and others, that it is almost impossible to effect this in persons labouring under suppuration of the liver.

7. The sanguine temperament is less susceptible to the action of Mercury than the nervous and lymphatic.

* On Poisons; p. 414.

Ibid , p. 408.

Lancet, 1843-44, p. 278.

§ On Diseases of Children, p. 108. || Clinical Medicine.

8. An animal diet retards, and an antiphlogistic regimen assists, the development of mercurial action. Acids also interfere with it.

9. In order to insure the certain and rapid effects of Mercury, the patient should carefully avoid exposure to great atmospherical changes. So important did Mr. Carmichael* regard this point, in the treatment of Syphilis, that he states that he deems it better, even though Mercury be strongly indicated, to dispense with it altogether, rather than to exhibit it, while the patient is exposed to a cold and variable climate. A similar opinion is expressed by Sir B. Brodie and Mr. Lawrence. Exposure to wet should be particularly avoided.