60. _The agents which are likely to injure the teeth_, have been, perhaps, too little regarded, especially when the importance of these organs to the horse is considered. Some grooms, to increase the appetites of the animals under their care, sprinkle vitriol, or sulphuric acid upon the food; and the horse will ultimately become fond of this kind of seasoning to his corn. Some veterinary surgeons, even of high standing, will administer monstrous doses of the sulphates in solution; and others will mingle, for a lengthened period, large quantities of the acids in the animal's water. No suspicion seems hitherto to have been entertained of the ill effects likely to ensue upon a mode of treatment, which is often prolonged for months. The human physician, however, has remarked, that most acids have a tendency to affect the teeth, and that sulphuric acid, whether in the diluted state, or in combination with substances of low affinity, is particularly destructive in this respect. The patient who now takes the soluble preparations of iron, is provided with an instrument to convey the liquid into the pharynx, and prevent any portion of it from coming in contact with the teeth. Those who swallow such a form of medicine, without employing the tube, soon exhibit the consequence in the general discolourization and decay of the mouth. The man, however, gulps his physic, and can rinse out his mouth if the taste be retained; the horse, when it takes a drench, holds the liquid for a considerable time before it swallows, and the administration of the fluid is not very quickly accomplished. Now, in proportion to the duration of contact would be the effect; and if the hasty deglutition of the one being cannot save the teeth from the ravage of the sulphate, is the prolonged retention of the substance likely to be without effect upon the same organs in the other? The horse, however, takes the sulphates of a strength which the human being would not survive--where the one for a dose swallows a grain, the other may imbibe a drachm. The consequences must bear some proportion to the 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 unorganized, 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