96 MATER i A MEDIC A AND THERAPEUTICS. 



Characters. A reddish liquid, alkaline to test-paper, 

 with the odour of lavender. 

 Dose. 2 to 8 min. 



b. Liquor Arsenic! Hydrochloricus. Hydrochloric 

 Solution of Arsenic. 



Source. Made by boiling Arsenious Acid with Hy- 

 drochloric Acid and Water. No decomposition occurs. 

 4 gr. in 1 fl.oz. 



Characters. Colourless, with an acid reaction. 



Dose. 2 to 8 min. 



From Acidum Arseniosum is made : 



c. Sodse Arsenias. Arseniate of Soda. Na 2 

 HAs0 4 .7H 2 0. 



Source. Made by fusing Arsenious Acid with Ni- 

 trate and Carbonate of Soda, boiling the products in 

 Water, and crystallising. (1) As 2 3 -f 2Na 2 N0 3 + 

 Na 2 C0 3 = Na 4 As 2 O r -f N 2 3 + C0 2 . (2) Na 4 As 2 7 + 



Characters. Colourless transparent prisms. Solu- 

 bility, 1 in 2 of water. The solution is alkaline. 

 Dose. tV to gr. 



Preparation. 



Liquor Sodae Arseniatis. 4 gr. in 1 fl.oz. 

 Dose. 5 to 10 min. 



From Arseniate of Soda is made : 

 Ferri Arsenias. See Ferrum. 



Non-officinal Preparation of Arsenic : 

 Donovan's Solution. Solution of Hydriodate of 

 Arsenic and Mercury. Dose, 10 to 30 min. 



ACTION AND USES. 

 1. IMMEDIATE LOCAL ACTION AND USES. 



Externally. Arsenious acid is a powerful irritant and 

 caustic. It is used occasionally to destroy lupus, epithelioma, 

 and other superficial or limited new growths, in the form of 

 "paste," composed of Arsenious Acid (1), Charcoal (l),RedSul- 

 phuret of Mercury (4), and Water. In the form of a dilute 

 ointment, it is employed in psoriasis to remove the scaly 

 growth. Arsenic must be used locally with great care, as it is 

 absorbed by the broken skin, ulcers, and mucous membranes, 

 unless sufficient inflammation be set up to throw it off. 



