Find sources: "Hand boiler"– news · newspapers · books · scholar · JSTOR ( January 2018) ( Learn how and when to remove this template message) The liquid inside a hand boiler does not actually boil. The "boiling" is caused by the relationship between the temperature and pressure of a gas. As the temperature of a gas in a closed container rises, the pressure also rises. There must be a temperature (and pressure) difference between the two large chambers for the liquid to move. When held upright (with the smaller bulb on top), the liquid will move from the bulb with the higher pressure to the bulb with lower pressure. As the gas continues to expand, the gas will then bubble through the liquid, making it appear to boil. The fact that the liquid is volatile (easily vaporized) makes the hand boiler more effective. Adding heat to the liquid produces more gas, also increasing pressure in the closed container. [2] Robison, John; Watt, James; Brewster, David (1822). System of Mechanical Philosophy. Vol.2. Edinburgh, Scotland: J. Murray. p.14, footnote. The liquid inside hand boilers is typically given different colors for visual appeal, and also to better show the liquid as it bubbles and moves through the boiler. James Lincoln; The hand boiler and how it does not work. Phys. Teach. 1 March 2022; 60 (3): 234–235. https://doi.org/10.1119/10.0009697

Hand boiler toy, built into a ballpoint pen. The warmth from the fingertips vaporizes some of the red liquid inside the tube, causing it to rise and bubble up into the top chamber as if the liquid was boiling. Mechanics [ edit ] This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Franklin, Benjamin (1769). Experiments And Observations On Electricity, Made At Philadelphia in America …. London, England: David Henry. pp.489–492. A hand boiler is a toy made out of hand-blown glass and filled with a special liquid called ethyl alcohol. The boiler consists of a larger lower bulb and smaller upper bulb, connected together by a twisting glass tube. This liquid inside the boiler is special because it appears to boil at a low temperature. And all it needs to do so is the heat of your hand. As you probably know, water boils at a temperature of about 100 degrees Celsius. With a hand boiler, the temperature of your hand is enough to cause the liquid to bubble and appear to boil.

A hand boiler or (less commonly) love meter is a glass sculpture used as an experimental tool to demonstrate vapour-liquid equilibrium, or as a collector's item to whimsically "measure love." It consists of a lower bulb containing a volatile liquid and a mixture of gases that is connected usually by a twisting glass tube that connects to an upper or "receiving" glass bulb. If you have cold hands the hand boiler will not work as well since the heat from your hand is not high enough to cause the liquid to evaporate and boil. You can try it out on a cold winter day, after you come in from outside. See what happens!

h {\displaystyle \Delta h} = the height of the column of fluid above the fluid's level in the lower bulb When holding the bottom of the boiler with your hand, the liquid inside becomes exposed to the heat of your hand and it begins to evaporate. Its pressure increases and the liquid expands. As a result it shoots up the glass tube and settles in the top bulb, since it cannot go any further. Next, the vapor bubbles (created by the evaporation process) travel up through the glass tube from the bottom bulb and into the liquid in the top bulb. These vapor bubbles force themselves through the liquid and cause it to bubble, giving the appearance of boiling. This process continues as long as the heat of your hand is applied to the bottom bulb. A hand boiler functions similar to the " drinking bird" toy: [1] The upper and lower bulbs of the device are at different temperatures, and therefore the vapor pressure in the two bulbs is different. Since the lower bulb is warmer, the vapor pressure in it is higher. The difference in vapor pressure forces the liquid from the lower bulb to the upper bulb. Thus:p {\displaystyle \Delta p} = the difference in vapor pressure between the two bulbs (which can be determined via the Antoine equation)