Think we carried just about everything and anything in them that would fit through the hatch, including ammunition.
Remember finding chippy glued to the lid of the ones we had aft one night when I was checking the steering gear. He had had a "good weekend" and decided to cool off down aft and have a sleep there forgetting they had recently been painted.
We used to carry general cargo in them outward bound (aft) and then put the steam coils in them for a homeward bound cargo of Latex. Used to have quite a time keeping the temperature at a constant 115 deg f (i think that was the figure). Then it would sit in wagons in Hamburg in the middle of Winter and solidify.
Aye, happy days..........