MINERAL OE INORGANIC POISONS 33 



numerous synthetical organic arsenic derivatives, for many 

 of which science is indebted to the work of Ehrlich and 

 his school. Cacodylic acid, (CH3)2AsOOH, is a long-known 

 pentavalent arsenic compound, and is relatively inocuous 

 in comparison with the trivalent cacodyl compounds above 

 named. Atoxyl, used in trypanosomiasis, and ' 606,' used 

 as a specific for syphilis, are more recent examples. 



But atoxyl may cause poisoning, as in the case observed 

 by Wooldridge,* who gave a bulldog 0-1 of a gramme in 10 

 per cent, solution on alternate days. After four doses the 

 animal died, having shown symptoms of poisoning. Accord- 

 ing to Miessner,^° cattle suffering from foot-and-mouth 

 disease are susceptible to salvarsan (' 606 '). being killed 

 by 45 grains intravenously. 



In view of the importance and frequency of arsenical 

 poisoning, the chief channels of administration may be 

 here summarised : (a) Administration of the drug for 

 malicious purposes, in mistake for other drugs, or in in- 

 correct medicinal dose. (6) As the result of dipping (see 

 below), (c) By local application, as in the treatment of 

 warts and mange, {d) By the accidental partaking of dips, 

 weed killers, rat powders, and the like, (e) Administration 

 by horse attendants to improve the animal's condition and 

 coat. (/) By contamination of water and herbage through 

 the neighbourhood of metal smelting works or mine 

 refuse. 



Toxicity of Arsenic. — The garlic-smelling vapour of free, 

 or metallic, arsenic is toxic, probably oxidising in part to 

 arsenious oxide. Finely divided metallic arsenic is also 

 dangerous when rubbed into the skin; but, in coarser 

 division, chemically pure arsenic is harmless when given 

 internally. Similarly, coarsely powdered white arsenic, which 

 is sparingly soluble, can be given in large doses to dogs 

 without ill effect. Thus 270 grains of coarsely powdered 

 white arsenic failed to kill a dog, as also did 15 grains a 

 day over four months ; but xu grain of potassium arsenite 

 and 2^ grains of sodium arseniate proved fatal when given 



* See Finlay Dun, 'Veterinary Medicines,' 1910, p. 284. 



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