Abstract: A bubble device for simulating the flow of liquid through a transparent tube, the device including an upper reservoir, a lower reservoir, a bubble generation section, a bubble refining section and an interconnecting transparent tube containing a volatile liquid therein. When the lower reservoir is heated and the upper reservoir is cooled, the volatile liquid is driven from the lower reservoir by the presence of heated vapor of the volatile liquid. Eventually, the heated vapor expands to the bubble generation section whereby bubbles are generated and caused to pass through the bubble refining section to break up the bubbles into smaller bubbles which travel upward through the transparent tube. A control circuit is used to maintain a constant temperature differential between the upper and lower reservoirs in order to ensure the proper and continued operation of the device.