PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 3S3 



loride of copper, perchluride of iron, dilute aqua regia, or any solutioti which 

 parts easily with chlorine, becomes covered with a greyish layer of cuprous 

 chloride, which is very sensitive to liffht. A negative placed ou apiate so 

 sensitivised gives a positive picture of great beauty. 



Manufacture and Use of Furs. 



The discussion of this subject was opened by Dr. D. D. Parmelee, who 

 said: 



In the prepared state the skins are called fur; but without preparation, 

 they go by the commercial name of peitry. 



In Russia, Poland, East Prussia, Iluiigary, Bohemia, and Saxony, lambs' 

 skins constitute an essential part of the dress of thousands among the 

 lower classes, and the skins of various other animals may be considered as 

 articles of absolute necessity 



So early as the sixth century, the skins of sables formed an article of 

 fashionable attire at Pome, and were brought from the confines of the Arc- 

 tic Ocean, at great cost, to supply the demand of that wealthy cayjital. 



The traders of Italy brought a considerable supply uf furs to England in 

 the time of Edward III., so much so that this monarch prohibited their use 

 except among the wealthy classes. 



The Canadian fur trade was commenced by the French, soon after their 

 settlement on the St. Lawrence. 



The company formed in London, and called the Hudson's Bay Company, 

 was charterc-d by Cliarles II. in 1670. This prosperous company founded 

 many establishments, and carried on its trade for more than a century, 

 when it met with a powerful competitor in the form of a new company 

 composed of wealthy and influential British settlers in Canada. This second 

 company was called the Northwest Ci>mpany, and its chief establishment 

 was at Montreal, though trading upwards of 4,000 miles further to the 

 northwest. After long dissention the two companies united into one, under 

 the name of the Hudson's Bay Fur, Company. . 



The Indian trade of the great lakes, upper Mississippi, etc., was enjoyed 

 by the Nurth American Fur Company, — having its chief establishment at 

 New York. 



Important as is the trade of these companies, yet the most costly and 

 highly esteemed furs are furnished by the trade carried on by Russia: The 

 ermine is one of these, a fur which is produced in many countries, but only 

 in perfection in Russia, Sweden, and Norway. 



The colder the climate, the finer and warmer "is the fur of animals. The 

 finest furs are iln^refore brought from the colder regions. The effect uf 

 cold on the Hudson's Bay lemming was made the subject of an experiment 

 during Ross's voyage. The little creature was kept in a warm cabin dur- 

 ing several months. It retained its summer fur. It was then exposed on 

 deck at night, to a temperature of 30 degrees below zero. After one night's 

 exposure, the fur on the cheeks, and a patch on each shoulder, had become 

 perfectly white. On the second day those patches had extended, and the 

 posterior part of the body and flanks had turned to a dirty white. During 

 the next four days the changes continued, and at the end of a week the 

 animal was entirely white. On examining the skin it was found that all 



