BUREAU OF PLANT INDUSTRY. 157 



studies of the relation of car insulation and other factors in con- 

 struction to the protection of perishables against freezing. The re- 

 sults of the work thus far have entirely corroborated the results of 

 the previous season and have clearly shown that through certain 

 modifications in the construction of ice bunkers, the use of racks 

 or false floors^, and with better insulation and minor modifications in 

 car construction it is entirely practicable and feasible not only to 

 increase the eiliciency of refrigeration, but to effect marked economies 

 in the transportation of perishables. 



The use of racks combined with the insulated bulkhead basket 

 type of bunker makes possible a much more rapid refrigeration — 

 that is, quicker cooling, the maintenance of lower temperatures in 

 transit, more uniform temperatures throughout the load, and par- 

 ticularly the maintenance of lower temperatures in the top tiers in 

 the middle of the car, where it is ordinarily very difficult to obtain 

 satisfactory temperature conditions. With this kind of equipment it 

 is entirely feasible to use small amounts of salt at the initial icing or 

 during the first two or three icings in such a way as to accelerate the 

 rapidity of cooling, in some cases to accomplish a quickness of cool- 

 ing comparable to some extent with precooling in either warehouse 

 or car-cooling plants. This rapidity of cooling can be accomplished 

 wuth practically no extra cost and no delay for cooling, the extra 

 amount of ice consumed during the cooling process being more than 

 saved on reicing during the latter half of the trip, especially where 

 cars are adequately insulated. 



It has also been demonstrated to be entirely practicable to effect 

 considerable economy as regards icing where cars are properly insu- 

 lated and constructed. Not only does the modified type of bunker 

 require less ice to accomplish the same refrigeration or better 

 refrigeration than is now ordinarily obtained, but with adequate 

 insulation a number of icings can be eliminated en route, resulting 

 not only in a saving of ice, but in running time and the expense 

 involved in switching, reicing, etc. Further economies are effected 

 through the practicability of considerably heavier loading, making 

 it possible to load the cars with a higher minimum than is now 

 customary. This factor alone is one of very great importance, espe- 

 cially at this time, when there is such a serious shortage of cars for 

 the movement of perishables and other foodstuffs. 



The results clearly demonstrate that with improved car construc- 

 tion, proper loading, and judicious salting the upper tiers can be 

 cooled to a temperature as low or nearly as low as that usually main- 

 tained in the bottom tiers under ordinary refrigeration with the 

 present equipment. As there is no real problem at present in keeping 

 the bottom tiers sufficiently cooled to carry perishables through to des- 

 tination in good condition, it is readily seen that if it is possible and 

 practicable to carry the top tiers at the temperatures now ordinarily 

 maintained in the bottom tiers it is entirely feasible to markedly 

 improve the condition in which vegetables arrive on the market and 

 to eliminate a vast amount of deterioration and economic losses 

 now due to the poor condition in the top tiers of perishables. It also 

 makes possible the shipment of tree-ripened or more fully matured 

 fruit in good condition, thus supplying the consumer w^th a product 

 possessing the maximum of good eating quality. 



