That is a Spray Powder Attachment. It looks like it would fit a Harris torch only. ( I sell Spray Powder torches ) You fill the Hopper with either Nickel Cast Powder to repair Cast Iron or to do Build up on shafts, Bearing Surfaces etc. Or you can put in a hard Surface Powder to Hard Surface Lawn Mower Blades, Plow Skids, Chisel Plow Teeth etc. The one in the Pic must be old because I have not seen one exactly like it. This is a Very Nice and easy way to do repairs. You can fix cast Iron easily and it will not crack like it often does when you stick weld it. Under the hopper there is a rubber tube about an inch long. It becomes collapsed if you do not store it with the lever depressed. You can replace it. To test this part, Hook it to the proper torch handle and turn on the Oxygen to 40#. Depress the lever and see it will suck itself to your palm. If so, Its ready to go. If you have VHS I can send you a tape to watch the how to on this.
Thanks.