TRANSPORTATION OF FISHERY PRODUCTS 321 



60-pound halibut, are usually shipped unboxed. The boxes are stacked as high as 

 physically possible in the car, with the determining factor being the inside 

 dimensions of the refrigerators. The fish-carrying capacity of a refrigerator car is 

 limited by its size, rather than by the weight of the fish. The size of boxes com- 

 monly used for some Canadian Pacific Coast species of fish are given in Table 84. 



Table 84. Sizes of Wooden Boxes for Frozen Fish. 



Outside dimensions of 



Weight of fish Kind of fish ^.^ "'"^ ^^ ''""''^ 



o fishing companies in 



Canada 



( lbs. ) ( inches ) 



150 Salmon or "chicken" halibut 42 X 20 X 14M 



200 Salmon 42 X 22 X ISYz 



200 Halibut, 10-20 lbs. 45 X 23 X 14 



300 Halibut, 20-40 lbs. 51)4 X 26)4 X 17J4 



400 Halibut, large 55M X 26J4 X 18M 



In the case of carload lot shipments of frozen fish the shipper stipulates on 

 the shipping bill the frequency of reicing, the amount of ice to be used, and the 

 proportion of salt to be added. As the importance of lower temperatures for 

 transport is becoming recognized, more and more shippers are requesting 

 "Maximum refrigeration," which implies ice and salt in eutectic proportions and 

 the filling to capacity of the bunkers at the designated stations or intervals. 

 Reicing instructions vary with the type of car employed. For example, a shipper 

 using an end-bunker car may request reicing to capacity to be regularly carried 

 out with chunk ice and 30 per cent salt at all icing stations; whereas the same 

 shipper, using an overhead-tank car, may not wish reicing unless the top tempera- 

 ture rises above 10° F (— 12.2° C) and 2400 pounds of ice and 30 per cent salt 

 are used. Since the cooling in the overhead-tank car is not as dependent upon the 

 amount of ice in the bunkers as is that in the end-bunker car, there is no need 

 to keep the bunkers full of the cooling mixture. 



However, all shippers of frozen fish do not demand 30 per cent salt in their 

 reicing instructions. Concentrations requested vary from 12 per cent to 30 per 

 cent depending upon the outside temperature and the type of car used. The 

 demand for the higher concentrations seems to be increasing however. 



It is also important to note that the method of determining the quantity of salt 

 to be added to a given amount of ice in a bunker is not on a true percentage basis. 

 "30 per cent salt" in railway terminology means 30 pounds of salt to 100 pounds 

 of ice, which is approximately 23 per cent salt in the resultant mixture. The re- 

 lationship between railway methods of determining the salt concentration in a 

 given mixture and the true concentration, together with the approximate tempera- 

 tures that might be expected in the resultant mixtures, as given in the International 

 Critical Tables, have been set down in Table 85 (p. 322). 



Railroad Containers 



Special containers are sometimes used for the transport of perishables on rail- 

 way cars, trucks, and ships for relatively short trips (a week or less). Usually 



