QUESTIONS AND ANSWERS 33 



ABSENIC 



Give the properties of arsenic and name some of the compounds of 

 arsenic used in medicine. 



Arsenic is an odorless, tasteless, steel-black non-metal with a 

 metallic appearance. It is very brittle and volatilizes unchanged 

 and without melting when heated to 180° C. without access of air. 

 In the air it burns with a bluish-white light and gives forth an odor 

 which resembles that of garlic; insoluble in water; occurs as an 

 opaque powder or in irregular masses. 



Compounds of arsenic used in medicine: Fowler's solution, 

 arsenious acid, arsenious iodide and sodium arsenate. 



Write the chemical formula of white arsenic. State the occurrence of 

 arsenic in nature. 



"White arsenic, or arsenious acid, AsjOj. 



Arsenic sometimes occurs in nature in the native state, but 

 generally as a sulphide or oxide. 



Describe the making of one preparation of arsenic that is used in 

 medicine. 



Fowler's solution, liquor potassii arsenitis. Dissolve one part 

 arsenious oxide and two parts of potassium bicarbonate in ten parts 

 of distilled water by boiling. Add enough distilled water to make 

 ninety-seven parts and then add three parts of compound tincture 

 of lavender. Filter through paper. 



Give Marsh's test for arsenic. What other element gives a similar 

 reaction? How may these two be distinguished? 



Make a hydrogen generator with a flask containing zinc and 

 hydrochloric acid. Ignite the hydrogen escaping through the tube. 

 Pour into the generating flask a few drops of any compound of 

 arsenic. Hold a piece of cold porcelain against the flame, and a 

 black, mirror-like stain of metallic arsenic will be deposited upon it. 



Antimony compounds give a similar reaction. The arsenic stain 

 is soluble in a solution of sodium hypochlorite, whereas, the anti- 

 mony stain is not. 



Mention a common substance containing arsenic. 



Paris green. Arsenic is also found in lead shot, it being used to 

 harden the same. 

 How should the contents of the stomach be examined for the presence 

 of arsenic? 

 Examine under the microscope for solid arsenious oxide. Then 

 apply Marsh 's test given above. 



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