A robbory of gold bullion occurred at Sidney, Nebraska, yesterday, when the Union Pacific Express was robbed of between $120,000 and $200,000. The bullion was on a truck in the oxprcss office, and at the time of the robbery tho agent was at dinner. It constated of bricks and bars from different mills. The larger part of it was recovered later from under a pilo of coal near the track of the railroad. Tho immenso weight of the treasure (480 pounds avoirdupois) prevented the robbers from getting away with it all. Of the quantity miBsing is a brick valued at $3,000 and$2,000 in an express paokage. The robbers are being pursued by the Rocky Mountain Detective Association.