334 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



flesh ; it was in fact juice of tlic flesh ; soup, witli all its valuable and 

 restorative properties. The brine is filtered to free it from any particles 

 of meat or mechanical impurities, and then pinired into bladders, or into 

 boxes made of skins or parchment paper, which are suspended in fresh 

 water in a suitable tank. The water in the tank must be changed every 

 24 hours. All salt and saltpeter will pass by what is called osmetic force, 

 through the pores of the bladder or other septum in the course of two or 

 three days, and the pure juice of the flesh, fresh and Avholesome, will be 

 retained. This can be concentrated by evaporation, and prepared for use. 



Prof. Joy then exhibited several specimens of parchment paper, which 

 is a cheap material for accomplishing the separation by dyalisis. It is 

 made by subjecting' common paper to the action of sulphuric acid of a 

 certain density. All substances arc now classified as crystalloids and col- 

 loids, which are separated by this process of dialysis. In the application 

 made by Whittelaw, the crystalloid, common salt, passes through the mem- 

 brane, and the colloids, containing animal extract, remain behind. It was 

 Liebig's opinion that the scurvy and other diseases afflicting those whose 

 principal diet is salt meat, arise from the absence of these animal extracts 

 which are retained in the brine. 



Mr. Nash remarked that the exposition now made was a strong' argu- 

 ment against preserving meat by means of salt. 



Waste Sewerage. 



Prof. Joy said when he was last in Europe he had frequent conversations 

 with Liebig on an excursion to Lake Geneva, Switzerland. Liebig has 

 contributed more than any other man to the utilization of waste products; 

 it has been the principal labor of his life; he has invented many processes 

 himself, and has directed tlie attention of the world to the subject. His 

 great grief is the waste of fertilizing material in the sewers. He spoke 

 repeatedly of the loss of this material which is going on in the city of New 

 York. 



Waste Bones. 



Bones are not now as much wasted as heretofore ; they are made into 

 handles and button,s; and when bone is decomposed, its phosphate of lime 

 is a valuable manure, and it is also the source of the phosphorus used in 

 our matches. 



Waste Vulcanized Rubber. , 



There seems to be a want of some ready method of devulcanizing old 

 India rubber. Several patents have been issued for this purpose, but the 

 fact that there is no d(Mnand for worn-out articles of rubber, would lead us 

 to conclude that this material is not utilized to an}' great extent. 



Slag in Iron Furnaces. 



Prof. Joy also visited Mantsel, where Luther Avent to school 300 years 

 ago, and saw the iron mines in which Luther's father worked. At this 

 place the slag has accumulated in mountains. People are constantly at 

 work, you may be sure, at plans for extracting something of value from 



