388 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



charge over white paper, to determine whether any of the powder 

 escapes unburned. 



Mr. Be Brame. — I will try that experiment. 



ARTIFICIAL FORMATION OF ICE. 



The Chairman spoke of the importance of the snbject of refri- 

 geration, upon the transportation of fruit. The fruits imported 

 from warm climates are now more than one half destroyed by 

 exposure on the passage. This year, the importation being unu- 

 sually great, three-fourths on an average, of all the shipments, 

 have been destroyed. Those which are received in a sound state 

 are very unlike the fruit where it is grown, because they are 

 picked in an unripe state and ripen very imperfectly. "VVe need 

 refrigerating vessels, which shall go to the southern ports loaded 

 with ice, and removing three-fourths to seven-eighths of their 

 cargo of ice, shall bring back a load of ripe fruits suited to our 

 market. By this means, the fruit business which is now so pre- 

 carious, might be made more profitable and certain, and the com- 

 munity largely benefitted. A somewhat similar plan has already 

 been adopted in land transportation. Every third or fourth day 

 a car arrives in this city from the far west, loaded with dressed 

 meat and game ; and they arrive in the finest condition. They 

 are here stored in a building so prepared that they can be kept 

 with safety until they are required for use. 



Prof. Twining explained his method of forming ice by the 

 evaporation of ether. His attention had been called some fifteen 

 years ago to the making of ice ; and be had tried two methods: 

 first, the expansion of air ; and second, the evaporation of some 

 liquid. The first method he had not found available in practice; 

 but by the evaporation of ether, he could freeze a pail of water 

 with extreme rapidity. Indeed, in his first experiment, the water 

 froze' too rapidly, producing a porous substance like hoar frost. 

 It must freeze more slowly in order to form clear and compact 

 ice. His method had been used in forming cakes of ice twelve 

 inches square and six inches thick, and these could be obtained 

 in twenty-four hours. Such cakes could be furnished in any 

 number that might be desired. They weigh thirty pounds a piece. 

 The vessels in which the ice forms are never broken by the expan- 

 sion of the ice, because the watur freezes from the outside, the 

 interior being all open water. The cost of the ice depends upon 

 the magnitude of the establishment. With coal at $10 a ton, 



