STUDIES OF POULTRY. 23 



if part of the carload has been in a freezer for forty -eight hours or 

 more, the loading is a comparatively simple matter, because the 

 most recently killed stock is put in the lowest layers next the bunkers, 

 where the temperature will frequently fall to 10 F. (12 C). 

 Often the air around the top layer, 4 feet from the floor, next the 

 bunker, Avill have a temperature not exceeding 30 F. (1 C.). The 

 boxes which have been in the freezer are then loaded in the central 

 part of the car and packed together as tightly as possible, serving as a 

 source of cold where it is most needed, namely, in the middle of the 

 car, where the refrige'ration from the bunkers is least. 



MIXED CARS. 



If the car is to be loaded with a mixture of poultry and eggs, as 

 very frequently happens, the problem is much more complicated. 

 If ice and salt are used in the bunkers, and if the poultry and eggs 

 go into the car well chilled, the temperature may be sufficiently low 

 to crack the eggs. If, on the other hand, salt is not used with the 

 ice, it becomes a difficult matter to keep the poultry sufficiently cold 

 to carry without deterioration if the haul is a long one. If such 

 mixed cars are to be handled, and this is oftentimes a commercial 

 necessity, it is advisable to chill the poultry as thoroughly as possible, 

 piling the boxes low in the car and against the ice bunkers. The eggs 

 should be artificially chilled to as low a temperature as possible 

 before they are shipped, and they should then be placed in the middle 

 and upper layers of the load. 



Since the ice bunkers are at either end of the car, it follows that 

 every additional foot away from them will mean a rise in tempera- 

 ture; and since there is no method of inducing artificial circulation 

 in general use, by which the heavy cold air at the bottom of the car 

 can be forced to the upper part, it follows also that every foot above 

 the floor means a rise in temperature. The mistake is frequently 

 made of packing goods too high in a refrigerator car. Where great 

 efficiency is necessary, as in the handling of poultry, the height of the 

 load should be not more than 4 feet. 



The railroads have established icing stations where the cars are 

 inspected and iced as conditions demand or as the instructions of the 

 shipper specify. 



INSULATION OF CARS. 



The temperature throughout long hauls and in different parts of 

 the car has been studied by means of thermographs. Great varia- 

 tions are observed, due, of course, to the construction of the car, the 

 atmospheric temperature, and the temperature of the goods being 

 carried. 



[Cir. 64] 



