The Helpless Helper (1927)

Als father Professor Rockenrye has discovered a gasoline substitute He can drop it on a toy train or wind up toy and the train will start running and the toy will start moving Als girl Rose is at his house and opens the door when Als rival arrives The big lug is there to whisk her away and marry her Stupid Al gives the rival a drink of the formula causing the rival to spit fire Al then spills all of the remaining formula ruining the Professors hope of fame and fortune