We see that reaction (4) could catalyze the decomposition of hydrogen peroxide by a mechanism analogous to that with reaction (3) described previously. And where would the quinone and quinhydrone come from? The walls of the chamber would be coated with particles of solid quinones from the previous explosion and quinone reacts with hydroquinone immediately to give quinhydrone. Entomologists have observed that the solution of hydroquinone in hydrogen peroxide from the reservoir of the bombardier beetle reacts slowly when exposed to air. I t is plausible that the initial priming of the explosion chamber takes place by this process. Thus it seems likely that the bombardier beetle utilizes an autocatalytic reaction, injecting more reactants into the reaction chamber whenever its defense mechanism is triggered. Faster Dinner via Molecular Potential Energy
taining some water and a wick running from end to end. It is inserted in a roast with one end exposed to the heat of the oven. The kinetic energy available at the hot end causes the liquid there to vaporize, increasing the intermolecular potential energy. The thermal energy is thus converted to potential energy. The gas formed fills the tube and when the molecules strike the cold wall of the tube at the interior of the meat, they condense to form a liquid again. On condensation, the potential energy stored in the gas is released as kinetic energy and ultimately causes the chemical reactions which convert raw meat into something which we find palatable. The wick carries the water back to the hot cnd by capillary action and the process continues.
A Footnote to the Methanol Lighter Exemplum
Professor John C. Bailar, Jr.'s exemplum on the methanol lighter was published in this column in April, 1970. Some of the teachers who tried to duplicate the experiment had trouble with it. Thanks to James A. Contribution by Sherwood A. Modestino, Spencer of the Choate School in Connecticut we have Worcester Polytechnic Institute learned that the lighter has been commercially available The cooking time for a roast of beef or other meat can recently under the brand name Magique Windproof be reduced by up to 50% by a newly developed d e ~ i c e . ~ Lighter. Mr. Spencer has two and has used then in It's a "Sizzle Stik," similar in function to the familiar his chemistry classes for exactly the purpose Professor aluminum roasting pins used to speed up the baking of Bailar described. Unfortunately his source of the potatoes, but operating on a different principle. lighters is no longer in existence. If any reader can inform us of a present supplier, we will publicize it in this column. fllustrating molecular and thermodynamic principles o f phase transitions
The new roasting pin operates on the principle of the "heat pipe,"4 transferring the energy as intermolecular potential energy rather than by a gradient of kinetic energy as in the conventional device. It consists of a sealed hollow tube of stainless steel con-
706
/
Journal o f Chemical Education
For those interested in lecture demonstrations, this is available from Horizon Industries, Dept. PP, 3625 Horizon Dr., Lancaster. Pa. 17601. Price 89.95. The manufacturer cites several advantages of the device in addition to saving time. See Sei. Amer., 218, No. 5, 38 (May, 1968), for more applications of theseinterestingdevica.
