PEOCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 549 



mixture, the milk will be frozen into ice cream. SnoAV and salt 

 form a freezing mixture, which extracts caloric from any sub- 

 stances with which it comes in contact. I will state the circum- 

 stances which first called my attention to the effects of salting 

 the streets. Sometime after my appointment as city physician, 

 by Mayor Wood, as I was walking one day up Broadway, I sa'v 

 near Canal street, a team of four fine horses belonging to Mr. 

 Herring. The wheel horse was standing on the snowbank near 

 the curbstone, and was resting comfortably on his four feet ; but 

 the other three horses were standing in the water which filled the 

 middle of the street, and I was surprised to see that each of them 

 was standing on only two of his feet. Stopping to observe them, 

 I soon saw them change their position, putting down the feet 

 which they had been holding up, and raising the others out of 

 the water. Seeing that the horses were fancy animals, I asked 

 the driver if this was some trick that he had been teaching them. 

 He replied that it was not, and remarked that he supposed the 

 horses raised their feet to get them out of the cold water. I 

 then put my finger into the water, and discovered that it was 

 extremely cold. This led me to investigate the subject, and I 

 soon became satisfied of the very deleterious effects of the prac- 

 tice of salting the streets. Never, in the history of the world, 

 was such an event known as the freezing of a horse's hoof. Every 

 blacksmith knows, and every person who has ever seen a horse 

 shod knows, that you may burn the hoof with a red-hot iron, or 

 you may stick nails into it, without producing any sensation. It 

 is an inert mass. So long as a horse stands upon the surface of 

 the snow, he would not have his foot frozen, if he should stand 

 there forever. But when he puts his foot into a freezing mixture 

 that is in a liquid state, so that the liquid comes in contact with 

 the corona of the foot above the hoof, where the parts are alive 

 and sensitive, full of blood vessels, then the foot may be injured. 

 I have at my office, specimens of horses' hoofs that have sloughed 

 off" in consequence of injuries received to the feet by the animals 

 standing in the salt slush in the streets. As Dr. Gardiner has 

 well remarked, this question is simply a matter of dollars and 

 cents to the railroad companies. When a manager shows the 

 stockholders that he has cleared a track with $60 worth of salt, 

 when it would have cost $460 to clear it with shovels, they con- 

 clude that he is an excellent manager. They do not think of the 

 horses which will be dying a fortnight hence, or perhaps next 



