92 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



ice, tlie material and shape of the box — all are things of importance, and 

 not the least elements of a practical economy. 



Greater judgment, however, is demanded in freezing for a subsequent 

 storing of wares. This is truly a new art, on which a patent was taken 

 ten or twelve years since in America, and it will become very imijortant. 

 I shall, therefore, venture to describe a so-called freezing-apparatus or 

 frost- vault. 



VI. 



THE ameeioa:^^ EEFRIGEEATOE. 



A refrigerator must not only keep the article cold, but it must keep 

 its temperature near zero or below the freezing-point; and to do this is 

 required not only a constant supply of ice, but also such an effect of ice 

 as wiU produce and maintain intense cold. 



Most persons have seen a common ice-chest for household use ; its 

 purpose is only to keep articles of food cool or cold. But no matter 

 how much or how often one may fill it with ice, the provisions will not 

 generally freeze ; partly because the ice-compartment is too small, partly 

 because the mass of ice cannot of itself send out sufficient cold over the 

 provisions to freeze them hard ; besides the distance from the ice is so 

 great that the intervening air makes freezing (in mild weather) nearly 

 impossible. 



The largest and best furnished freezing-vault which I saw was one 

 belonging to the above-named Mr. Eugene G. Blackford. It was, prac- 

 tically speaking, a cellerage 80 feet long, 11 feet wide, and 10 feet deep, 

 fitted up as a small store-room. The outer frame of the vault was much 

 like a ship's deck, tight, and composed of planks. A trap-door led down 

 to a room where it was dark and the temperature some degrees below 

 the freezing-point; on the day on which I inspected it there was a strong 

 summer heat of 35° C. (= 95 Fahr.). The ceiling itself was double, 

 and the lining was partly sawdust (to prevent the influence of warm air), 

 partly ice mixed with a certain proportion of salt (to send the cold in 

 the ice out over the room, "liberate " it, as it is called in physics). Along 

 the sides and at the ends and across the vault itself were constructed 

 large conduits or rather long reservoirs for ice mi^ed with salt, to act 

 on the air in all parts. The situation and shape of this reservoir form 

 a very important part of the apparatus. The art is to get the cold in 

 the ice, which is "liberated" with salt, to operate so that it will be of 

 the greatest benefit and also most valuable with least expense. As cold 

 or cold air "falls," these ice-reservoirs are placed highest up in the top; 

 the cold air must also fall right through the whole vault and cool the 

 entire room in its wandering. Were thej^, on the contrary, placed on the 

 sides or bottom, the cold liberated from the ice would simply fall along 

 or down the reservoir itself. Side-reservoirs would also merely form 

 a cold wall or ice-belt around the vault. Such a cold wall they have 

 also, but the ice of the reservoir is best utilized, as indicated, by allow- 



