This was the third railroad i visited during my vacation trip. (The second one comes next).
It was at Bala Lake in Wales. Ther was a steam gala during the day I visit. They had 5 or 6 loco's under steam and rode passenger and freight trains. The line is not very long, about 4 km and is almost completely straight, so no photo's could be made from the train during the ride.
It was originally a railroad to transport slate.
As a guess, similar cars were used in Brazil to haul
flammable material and possibly explosives for mining operations. The engine's were wood fired and possible sparks
could ignite the load if on an open car.