SIXTRENTIJ ANNUAL MEETING. (59 



the l)()(ly has a two-fold function; its so-called "latent heat," 

 determining whether its forni be solid, liquid or vap(jr. Its 

 so-called "sensible heat" determining its temperature. 



]\1 citing ice, blood heat, and boiling water fix couNenient 

 points on a scale of temperature which extends far below and 

 still further above this familiar range. If we are in contact 

 with a body having a lower degree of sensible heat than our- 

 selves, heat passes from us to it, occasioning the sensation we 

 call culd ; if we are in contact with a body of higher tempera- 

 ture than ourseh'es, we feel the inflow of heat from it to us, and 

 call the thing hot. Nature in each case is making for an 

 equilibrium in temperature and illustrating the first laws of 

 thermodynamics : which science, further, treats of the trans- 

 mutation of this indestructible, all-prevading energy, from one 

 of its forms to another, from motion to heat, latent or sensible, 

 and vice versa. 



The United States, "land of the free and home of the 

 brave," is preeminently the home and the land of refrigeration, 

 a fact attributable to several causes; variability and diversity 

 of climate; high standard of living; facilities for interchange 

 of products between distant localities ; variety of food products ; 

 the national liking for iced drinks, the householder's provident 

 habit of buying considerable supplies at a time instead of buy- 

 ing each day only the quantity for the day, as is the custom of 

 other lands; and lastly, the promptings of Yankee inventive 

 genius and commercial enterprise. 



Prior to 1900 natural sources of cold, chiefly ice from lakes 

 and streams, were emplo}'ed to some extent to preserve food, 

 but operations were limited to a few food products, and the 

 period for storing them was restricted. Practically the tem- 

 perature obtained was not below' 36 degrees Fahrenheit. Freez- 

 ing temperature could be had by use of salt with ice, but the 

 expense was excessive. The large space required for an ice 

 storage house, together with the limited range and imperfect 

 control of temperature, rendered impossible the extensive and 

 varied operations now made easy by employment of mechanical 

 means of refrigeration. Besides this, ignorance and neglect 

 of the importance of ventilation and regulation of atmosplieric 

 moisture made unattainable then such perfect preservation of 

 goods as is now accomplished. 



