4-16 SALTS OF THE HEAVY METALS 



ABGENTI NITRAS 



Synonym. Silver Nitrate 



Silver nitrate occurs as colorless, transparent, rhombic tabular 

 crystals, becoming gray or grayish-black on exposure to light in the 

 presence of organic matter; odorless, caustic metallic taste and solu- 

 ble in 0.54 part of water, and 30, of alcohol. It turns dark upon 

 exposure to light so should be protected from it. 



Doses. H. gr. v — ^xv; 0.3 — 1. Sh. and Sw. gr. ij — iij; 

 0.13—0.2. D. gr. y6—V2; (0.01—0.03). 



Preparations. 



Argenti Nitras Fusus. Silver nitrate toughened with hydro- 

 chloric acid and moulded into hard white sticks or pencils (Lunar 

 Caustic). 



' * Argenti Nitras Mitigatv^ (Mitigated Caustic). This appears 

 as moulded cones or pencils. It is made by fusing 3 parts of silver 

 nitrate, and 6, of potassium nitrate. 



Incompatibles. Silver nitrate is incompatible with organic 

 matter, bromides, chlorides, iodides, cyanides, "sulphates, carbonates, 

 phosphates, arsenates, and hydrochloric acid. It is explosive with 

 creosote. 



Action. Silver is one of the tnost toxic of the metals to bacteria 

 and protozoa but relatively non toxic to mammals. It possesses a 

 great affinity for proteids and is irritant, caustic or astringent ac- 

 cording to concentration. Applied to the skin, the nitrate is a 

 superficial caustic or escharotic. Its action is superficial because 

 it forms compounds with the tissues which are not soluble in an 

 excess of the proteid. The eschar is at first white but later becomes 

 black by oxidizing in the light. In order to remove the black stain 

 from the hands or skin it is necessary to wash the stain with a 

 solution of potassium cyanide or paint with tincture of iodine, and 

 bleach with a solution of sodium hyposulphite. In dilute solution 

 it is an unirritating astringent and antiseptic to mucoiis membranes 

 or raw surfaces, precipitating the proteids of the tissues and con- 

 tracting the bloodvessels. In concentration it is escharotic but al- 

 ways of a superficial action on account of the impermeable membrane 

 formed, which prevents penetration. It is also a very active antisep- 

 tic. 



Internally in therapeutic doses there is no action besides that of 

 astringent and antiseptic. Its action is largely confined to the 

 stomach because it is so easily precipitated by proteids, chlorides 

 and acids. The astringent action is entirely exerted upon the 

 stomach unless it is administered in keratin covered pills. 



Absorption and Elimination. Silver nitrate is largely elim- 



