7. ENERGY
Observations: Times for rise, black tape 11/% minutes, white tape, 9 min.
A. Interconversion of Energy
Note: When black and white paint was substituted for the tape, times were 1% and 5 minutes, respectively.
Reference: FINE,I., J . Chem Educ., 8, 929 (1931) Dem. 333-lnterconvenmn
of Energy
T o show: Various forms of energy being intercmverted. Materials: Special Device SD-333, see Figure. Dimensions are not critical. Two small dry-cell flashlight batteries, a &volt flashlight bulb and socket, a toy motor and on its shaft a pin-jack holding a 2-in. disc of red-blue cellophane (not shown in Figure) which on projection shows whether the shaft is turning; a box containing two Pt-wire electrodes in dil. H2S04,a toggle switch.
2. PRODUCTION OF HEAT Dem. 335-Heot
Off: Touching Flosh-bulbs
T o s h m : The burning of a photoflash bulb gives off enough heat to ignite a second bulh held against it. Materials: Two photoflash bulbs, forceps, l'/z-volt battery, cellophane tape. Procedure: Tape two photoflash bulbs so the bulbs are touching tightly. Project a 11/,-volt battery. (Care: hold bulbs in forceps; they would bum the fingers.) Hold the socket of bulb 1 against the terminals of the battery.
Observations: Bulb 1 ignites from the electricity; bulh 2 from the heat from bulh 1. Dem. 3 3 6 L o w H e d of Combusi;on of Guncotton
Experiment developed by LeRoy G. Hornbeck. T o show: That the heat of combustion of guncotton is too little to ignite gunpowder. Materials: H-4, guncotton or flash-pad paper (available at "Trick Stores") ; hlack gunpowder; string soaked in I
