THE FARMERS' REGISTER. 



519 



BO'ent into the ice, it would retain its solid iurm 

 for any lengih ol' lime. 



Tlie temperature ol" ice, when at iis nieltinir 

 point, is 32"^, Falirenlieil ; in order thai it may mell 

 into water, it must absorb 110 degrees ol" caloric, 

 Bulficieni lo raise its lemperaiure to 172 deji. but 

 which only changes ils lorni, Irom solid to liquid, 

 without rendering it any warmer than it was be- 

 Ibre. The water draining Irom the nieliing ice 

 being always at the same temperature with ihe 

 ice iiseif. SViihout the accession ol" these 140 de- 

 grees of caloric, therefore, ice would never be 

 melted into water. 



Could we consyuct a house of materials that 

 were perlect non-conduclors of caloric, the pre- 

 servation of ice contained in it would be complete. 

 As, however, we have no perlect non-conduciors 

 we must select for our purpose those substances 

 which conduct most slowly. The materials which 

 experience has selected for articles of clothing, 

 to preserve the natural temperature of our bodies, 

 stand at the head of the list of these substances, 

 and would also be the very best that could be used 

 to protect ice from the surrounding caloric, were 

 they not too dear and too perishable in their na- 

 ture. As these, however, cannot be employed, 

 for this reason, except in preserving small quan- 

 tities lor immediate use, we are obliged to resort 

 to others less perfect but cheaper and more inde- 

 structible. Among these are the Ibllowing, which 

 I have placed in the ordei of their relative resist- 

 ance to the passage of caloric, as determined by 

 Count Rutnfbrd and others ; those which oppose 

 the greatest obstruction to its passage being placed 

 first ; viz : 



Charcoal of light wood, 



Dry wood ashes, 



Tan bark, 



Wood, 



Sand, 



Bricks, 



Porous earth, 



Porous rocks, 



Dense rocks, 

 According to our data, one of the best modes of 

 forming the walls of an ice house would be to 

 make a frame work of timbers, say from 6 to 12 

 inches thick, to board it upon both sides of the 

 timbers and fill the spaces between the boards 

 with powdered-charcoal, dry wood ashes tan bark 

 or saw dust ; the floor and covering of the struc- 

 ture being protected in the same manner ; and on 

 filling it with ice a considerable thickness of straw 

 should be placed at the bottom, sides, and lop. 



Where these materials are not easily to be ob- 

 tained, logs of wood, built up in the pit, like a log 

 cabin, make a very good substitute ; more espe- 

 cially if filled on the outside, next the ear'h, with 

 charcoal, ashes, saw dusi, or tan bark. For this 

 purpose charcoal and ashes are preferable to saw 

 dust and tan bark, in consequence of their inde- 

 structibility. 



Bricks and stones, although often employed in 

 the construction of ice houses, are iess proper 

 than wood, unless lined on the outside with a suffi- 

 cient thickness of charcoal, ashes, or other im- 

 perfect conductors. 



Ice houses are frequently made, partly above 

 and partly below the general surface of the 

 ground ; the top being arched over and the earth 

 which was dug from the pit being thrown on the 



top of the structure in the form of a mound. This 

 is a very good form, provided all the sides are 

 |)rotected, by non-conduclors, Irom the caloric of 

 the soil. The caloric of the sun's rays, absorbed 

 by the surface of the porous earth in summer, 

 pusses through it with considerable difficulty, and 

 navels slowly to the interior ; passing olf again in 

 part, by the same t^lovv process back to the surlace 

 to t)e dissipated during the cold of winter. In 

 consequence of the difficulty with which it pene- 

 trates porous earthy matters, the daily changes 

 of temperature cannot be observed at a greater 

 depth than 3 or 4 ti-et, and the great annual vicis- 

 situdes are entirely lost belore they descend 100 

 \'eel below the surface. The earth's surface, 

 therefore, does not become heated or cooled ra- 

 pidly to any considerable depth, and deep caves 

 and excavations in the earth, preserve a scarcely 

 varying temperature, which approaches that of 

 the mean temperature of the region. This is the 

 temperature of the water of deep wells, or of 

 springs rising from some depth, which by compa- 

 rison appears cold in summer and warm in win- 

 ter. The mean temperature of this region is some- 

 where between 52 and 56 degrees, Fah.; twenty 

 or twenty-four degrees about the melting point 

 of ice ; so that there is always caloric enough in 

 the soil, below the surface, to melt ice, even du- 

 ring the winter season, and deep ice houses, 

 whether covered or not with a mound of earth, 

 hence require the protection of walls of non-con- 

 ducting materials. 



One of the most common causes of the rapid 

 melting of ice in ice houses, is the want of suffi- 

 cient drainage. If the water which drops from 

 the ice or sinks from the surface of the soil, can- 

 not drain away, but remains at the bottom of the 

 house in contact with the ice, it serves as a me- 

 dium though which the caloric of the earth pass- 

 es with facility, causing the rapid melting and 

 sinking of the ice. At the bottom of every ice 

 house, therefore, if it is not in a very sandy soil, 

 there should be a well of sufficient magnitude, or 

 the floorshould be raised to such a height above 

 •he earth as to prevent the water from ever com- 

 ing in contact with ihe ice. Decomposition, and 

 the Ibrmaiion of mephitic gases, as suggested by 

 one of j'our correspondents, cannot take place 

 under these circumstances : the most fermenta- 

 ble liquids do not begin their fermentation until 

 iheir temperature is raised above 32 deg. which is 

 that ol the water dripping Irom ice. 



Those houses which are not covered with a 

 mound of earth, should have a good roof, or what 

 is better, a tight room built over them, to prevent 

 the circulation of air as much as possible, and the 

 roof and sides should be rendered as nearly proof 

 against the passage of caloric as straw, or other 

 substances of the kind, fixed on the inside, as 

 stated byMr. Mentelle, can make them, and to pre- 

 vent as much as possible the absorption of the ca- 

 loric of the sun's rays, the whole exterior, roof 

 and all, should be well whitewashed; it being a 

 well established fact that much less is absorbed by 

 a white surfiice than by a black one. 



A great deal may be gained in the preservation 

 of ice, by putting it up during the very coldest 

 weather. For example, if ice be cut and expos- 

 ed for a sufficient time to the air, when the ther- 

 mometer is at zero, and packed away at that tem- 

 perature, it must become heated up to ils melting 



