Where is the pathogenesis of Fluoric acid found ? In the Materia Medica of American Provings . What is Fluoric Acid ? It is the acid combination of Hydrogen and FluoriQne ; it is very excoriating and is kept in rubber bottles, since it eats glass. How is our tincture prepared ? By dissolving 1 part of the pure acid in 99 parts of distilled water. Must be kept in gutta percha bottles. Drug power, 1/100. Give its general action. It acts principally on the bones and skin ; it also has some effect on the glands. It produces also a state of venous congestion and varicosis. It is well indicated often in the complaints of the old or those who are prematurely old. What are its symptoms on the bones and periosteum ? It produces caries of the long bones, with thin and excoriating discharges, relieved by cold applications. Dental fistulae and bone felons, with offensive discharges. What are its skin symptoms ? Roughness and harshness of the skin, with great itching in spots ; worse from warmth and better from cold. What is the relation of Fluoric acid to Silicea ? It follows Silicea well, and is especially useful after the abuse of Silicea in suppurations. Silicea is relieved by warmth. Fluoric acid by cold.