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quantity, nor will the composition of the horse's 

 tooth allow us to suppose that it is less affected by 

 chemical agents. The enamel of the horse is more 

 speedily acted upon than that of any other animal I 

 am acquainted with ; and the substance being un- 

 organized, the results obtained by experiments tried 

 on it when removed from the body, are as conclusive 

 as any effects produced during the life of the animal. 

 The sulphates are potent and valuable medicines ; the 

 Veterinary Pharmacopoeia could not afford to discard 

 them ; but they can be administered in substance, 

 and should with caution be exhibited in a liquid 

 form. I am positive when promulgating this opinion, 

 and nevertheless I have no instance of their injurious 

 effects to adduce. I have not been able to trace 

 caries in the horse to the use of the sulphates or of 

 acids, but the mind often recognises what the senses 

 fail to perceive ; and the fact is so clear to reason, 

 that it is not disproved, because it hitherto has not 

 been rendered plain to the vision. Neither does it 

 invalidate my conclusion to adduce instances where 

 the horse had been observed to exhibit no affection 

 subsequent to the use of these medicines. The 

 negative can establish nothing. The cause has not 



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