FORTY-FIRST ANNUAL CONVENTION 301 



unusually strong tank, as two bolts extend entirely through bot- 

 tom, sides and ends. As shown in cut, there are three divisions, 

 in the tank, one for a large can and two for shot-gun cans, it 

 was Prof. Frandsen's idea that one of these could be used by the 

 farmer's wife for keeping butter, milk and eggs. He has an ar- 

 rangement for this, of shelves fitted with a handle, so that it can 

 be lifted out at the farm wife's convenience from the shot-gun 

 can. 



The writer has been a little skeptical about this convenience 

 for the wife for fear of odors, but Prof. Bouska and Pjrof 

 Frandsen have provided for this by having a cover fit very closely 

 to this division. 



The Metal Tank. 



In various meetings that we have held, some objections have 

 been made to the metal tank on the ground that if it sprung a 

 leak in any way, the insulating material would lose its insulating 

 powder. To overcome this objection, we find that the insulating 

 material can be sealed in rubberoid paper which is waterproof, so 

 in this case, even if the tank did spring a leak, it would still re- 

 tain its insulating qualities. 



By expermental data, hairfelt is the most efficient commer- 

 cial insulator. Recently many flax straw preparations have come 

 mto use as insulators. It is reasonable to suppose that flax fibre 

 has practically the same insulating power as cotton, wool and 

 hemp canvas, which it resembles. The cost of these insulating 

 materials themselves is small. Applied in tank construction, the 

 metal inner and outer walls to support the insulator, are the main 

 cost. 



Doubling the thickness of an insulator increases its resist- 

 ance to temperature considerably more than twofold. By actual 

 test a tank of two-inch cypress was not far behind an inch of 

 hairfelt in resisting temperatures. 



Water transmits heat 27 times as fast as air. Cream set in 

 water will therefore cool 27 times as fast as cream left standing 

 in the air. 



The conductivity, designated by C, is the quality of heat that 



