272 ARSENIC 



and if held in the mouth shortly causes irritation. When 

 long kept it loses its transparency, and becomes opaque. At 

 a temperature of 400 Fahr. it is volatilised. Sprinkled on 

 ignited charcoal it emits a characteristic garlic odour. 

 Arsenic is soluble in one hundred parts cold, and in ten parts 

 boiling water, and in five parts of glycerin. Moderately 

 soluble in solutions of alkaline carbonates, and in diluted 

 hydrochloric acid (B.P.). Boiled in water for two or three 

 hours, the ordinary crystalline arsenic is converted into the 

 vitreous form, and in each pint 219 grains are dissolved. 

 Solubility is diminished by organic matters, but increased 

 by acids, alkalies, and alkaline arsenites. 



ACTIONS AND USES. Arsenious acid is a corrosive irritant 

 poison, killing either by gastro-enteritis or by nervous 

 paresis. Continued doses cause fatty degeneration. It is 

 prescribed as a gastro-intestinal stimulant and alterative, 

 acting especially on the digestive and respiratory mucous 

 membranes and skin, as an aid to growth and nutrition, as 

 an antiperiodic, and as a tonic in nervous diseases. It is 

 used externally as a parasiticide, antiseptic, and caustic. 



GENERAL ACTIONS. Arsenic belongs to the trivalent group, 

 which also comprises phosphorus, antimony, and bismuth. 

 These agents diminish oxidation, decompose albuminoid 

 tissues, produce fatty degeneration, and impair the glyco- 

 genic functions of the liver. With the exception of bismuth, 

 the members of this group are irritant, corrosive poisons. 

 The specific ' arsenic ' action is due to the negative ion of 

 arsenious acid. 



Locally applied, arsenic causes congestion, heat, and pain, 

 with destruction of tissue, but the slough is preserved by the 

 antiseptic effect of the poison. It is absorbed from any 

 mucous, serous, or skin-abraded surface, and exerts its effects 

 by whatever channel it enters the body. Small medicinal 

 doses directly stimulate the stomach and promote gastric 

 secretion. Beginning with small doses, animals shortly 

 acquire a tolerance of arsenic, and take with impunity doses 

 which would otherwise prove fatal. Full doses irritate the 

 surfaces with which they come into contact ; cause gastro- 

 intestinal inflammation ; in dogs and other carnivora 

 vomiting, diarrhoea, weakened cardiac action, reduced 



