•ffERCURY. 327 



occurs in the form of a bright lemon-yellow powder, of a specific 

 gravity of 6*444 ; it is inodorous, nearly insoluble in water, and 

 has an acrid taste. The sub-sulphate of mercury mixed with 

 liquorice powder, and snuffed up the nose at bed-time, is some- 

 times prescribed as an errhine in chronic ophthalmia. Taken 

 internally, in a dose of from four to six grains, it operates as a 

 powerful emetic. In smaller doses, it was formerly much em- 

 ployed as an alterative and diaphoretic ; but it is extremely liable 

 to act violently on the stomach and bowels, and as it has no 

 particular advantage attending its administration, it is nearly dis- 

 carded from practice in this country. 



Acetate of Mercury. Acetas Hydrargyri, Ph. E. D. — 

 This is prepared by dissolving three ounces of mercury in four 

 and a half ounces of diluted nitric acid, and adding a solution of 

 three ounces of the acetate of potass in eight pounds of boiling 

 water. The solution deposits crystals of the acetate of mercury, 

 which must be washed with cold distilled water, and dryed by a 

 gentle heat. The acetate of mercury, is now very seldom em- 

 ployed as an anti-syphilitic; it is considerably less active than the 

 preceding preparation, and forms the basis of the once celebrated 

 Keyser's pills. The dose is from gr. i. to grs. vi. twice a-day. 



Order II.— INFLAMMABLE MINERALS. 



This order comprises such mineral substances as 

 burn more or less easily, or whose principal character 

 is inflammability at not very high temperatures. When 

 solid, they are easily broken ; they are soft, yielding 

 easily to the knife ; their specific gravity seldom exceeds 

 2.0 ; they are composed chiefly of carbon or of sulphur, 

 either pure or combined with hydrogen, and more or 

 less earthy and metallic matter. 



