394 Trmisactions. — Chemistry. 



Art. LXIII. — Notes on Refrigeration. By Professor A. W. Bickerton. 

 [Read before the Philosophical Institute of Canterbury, 5th May, 1881.] 

 Some weeks ago, Mr. Montgomery, Chairman of our College Board, 

 requested me to give my attention to tlie means available for producing 

 such a slight reduction of temperature as might render it possible to ship 

 home the butter and cheese that was made in the Banks Peninsula and 

 other grazing districts of Canterbury. He assured me that the question was 

 of considerable importance, as there was a very large quantity of land 

 exceedingly suitable for grazing purposes and not very well adapted for 

 other branches of agriculture, yet the want of a market has hitherto pre- 

 vented its being fully applied to this object. I was afterwards consulted by 

 Mr. J. L. Coster, Chairman of the New Zealand Shipping Company. I 

 have, therefore, thought it desirable to give a brief statement of the ideas 

 that have suggested themselves in connection with the subject. 



Temperature may be reduced by three essentially different modes : 1st, 

 night radiation ; 2nd, the expansion of compressed air at ordinary tempera- 

 ture ; and 3rd, change of state — that is, solids becoming liquids and liquids 

 becoming gases. 



The liquefaction of solids is the basis of all the so-called freezing mix- 

 tures. The volatilization of liquids divides itself into two branches ; the 

 evaporation of water and the ebullition of such liquids as boil at an exceed- 

 ingly low temperature, such as liquid carbonic acid, sulphurous acid, 

 ammonia, ether, etc. Of these methods those that appear most likely 

 to be useful are night radiation, evaporation of water, expansion of com- 

 pressed air and freezing mixtures. 



It must be understood that the problem to be solved is a very different 

 one to the production of a daily supply of ice, for it is evident that if we 

 could obtain a perfect nonconducting air-tight chamber that once had its 

 temperature lowered, it would remain at that temperature for an indefinite 

 time, and require no further attention unless there were an internal action 

 such as chemical change or friction that would develope heat. There is no 

 substance but allows the passage of more or less heat, but substances differ 

 to an extraordinary extent in this particular. It would be a matter of 

 experiment to discover the most suitable nonconductor, though I think it 

 probable that well-carded wool of good quality would be the best. It would 

 also be a matter for experiment to ascertain how tightly this would have to 

 be packed to be most nonconducting. 



Having ascertained the most effective material and the conduction of 

 this material that offers the greatest resistance to the flow of heat, it would 

 be necessary to investigate the temperature and other conditions under 



