28 



Scientific Proceedings (30). 



placing it in covered trays of the kind referred to and transferring 

 them immediately to such a frame in a freezing room. The gen- 

 eral characters and relationships of the main parts of the apparatus 

 are clearly shown in Figure i. The structure and dimensions of 

 the glass trays are indicated in detail in Figures 2 and 3. See 

 pages 30 and 31. 



In the form of this apparatus now in use in this laboratory, each 

 "angle iron" skeleton is 20 inches high, 21 inches wide and 10 

 inches deep. Twenty five glass trays fit snugly into as many 

 stalls,' which are just a trifle wider and longer than the trays, and 

 are arranged in five tiers. The removable horizontal rods at the 

 front are so arranged as to prevent the trays from falling from the 

 frame if the latter happens to be tilted forward. The " angle 

 iron " fixtures at the rear prevent movement of the trays in that 

 direction when the frame is tilted backward. 



The glass trays are the essential parts of the apparatus and are 

 excellent food containers. Plates of ordinary glass furnish very 

 satisfactory covers for the contents of the trays. Such a glass 

 lid, trimmed to fit intimately, can easily be put in place and can 

 readily be elevated with a finger at the depression in the edge of 

 the tray, at one end. Air tight closure may be secured by plac- 

 ing over the tray a full-width strip of paraffined muslin before the 

 closely fitting lid is pressed down tight upon the ledge in the tray 

 which supports it.^ Paraffined muslin will not appreciably absorb 

 moisture from the contents, nor freeze fast to the latter, and can 

 be washed free from the slight amounts of food that may adhere 

 to it. If such a paraffined muslin strip is allowed to extend a 

 little beyond one end of the tray, the protruding portion serves as 

 a means of drawing the tray from the frame and also of lifting the 

 lid of the tray. Such paraffined muslin strips may be used again 

 and again. 



The trays are composed of thick flint-glass and therefore are 

 able to withstand unusally rough treatment. Neither the lids nor 

 the trays have been cracked by alternate cooling and warming 

 between the extremes of temperature to which they have com- 



1 Five additional trays may conveniently be placed directly underneath the lower 

 tier of trays in the frame. 



' Such closed trays full of meat may be kept weeks at a time in a refrigeration 

 room without losing weight. 



