SILVER. 253 



oil, when it is poured into iron tubes previously heated and greased, 

 to prevent the nitrate from adhering to its sides. When fused, 

 and cast into small cylinders, it is called the lunar caustic, or the 

 argenti nitras of the pharmacopoeias. In this state it is of a 

 blackish colour externally, and when broken, it presents internally 

 a radiated appearance. It is inodorous, has an intensely bitter 

 metallic taste, and tinges animal substances of a yellow colour, 

 which, by exposure to light, becomes purple, and ultimately black. 

 It is soluble in about its own weight of water at 60°, and is also 

 soluble in alcohol. It is decomposed by heat, by many of the 

 acids, by the alkalies, and many neutral salts, and by astringent 

 solutions. Some of the metals, also, particularly copper and 

 mercury, precipitate the silver from its aqueous solution, in a 

 metallic state. In the form of crystals, it consists of 64 parts of 

 oxide of silver, 22 of nitric acid, and 14 of water. 



The Nitrate of Silver was introduced as an internal remedy by 

 Angelus Sala, in the commencement of the seventeenth century. 

 Boerhaave highly extols it as a diuretic in dropsies;* in modern 

 practice it has been prescribed as a tonic and antispasmodic in 

 epilepsy, chorea, and angina pectoris. It is given in the dose of 

 \ of a grain, gradually increased to 4 grains or more, three times 

 a-day, in the form of a pill. A singular blueness of the skin is 

 sometimes observed after the protracted use of the nitrate of silver, 

 the whole surface of the body, especially those parts that are most 

 exposed to light, acquire a leaden-grey or livid hue, which often 

 continues for a long time after its disuse. When taken in an over- 

 dose, it acts as a corrosive poison ; the antidote for which is the 

 muriate of soda. Externally the nitrate of silver has been much 

 used as an escharotic, to change the surface of foul ulcers, and to 

 destroy strictures in the urethra, warts, fungous excrescences, and 

 incipient chancres. Its solution, in the proportion of from one 

 to five grains to the ounce of distilled water, is sometimes used as 

 an injection in fistulous sores, and as a stimulating application to 

 indolent ulcers, to apthous affections of the mouth, and to that 

 disease of the gums generally denominated scurvy. One scruple 



* Sec Boerlmavc's Chemistry, pt. ii. p. 2it7. 



Z 



