Huberf N. Alveo'
Princeton University Princeton, New Jersey
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TOPS in General Tested Overhead Projection Series
T o m , a series on overhead projection of chemical experiments, is hereby launched. The teacher uses drops; the student sees them on the screen live, in color, as huge as baseballs in test tubes six feet tall and two feet wide. Invisible macro-reactions become clearly visible 100 ft away. This is truly something new under the sun. What is new about it? Certainly not overhead projection per ~ e . ~ First, we propose to project all of beginning chemistry demonstrations, not just a few special ones. Second, only 28 devices will be required to carry out at least 1000 different experiments previously described in the Tested Demonstration series. Third, the stage of the projector is small--only 5 in. X 5 in.-larger than a standard slide (which is too small for showing heating or collecting gases) and smaller than the usual 10-in. X 10-in. stage which is too large for microoperations. Fourth, the stage is vertical: the class sees apparatus vertically in its natural macro-demonstration position. No Petri dishes here; the cells on the screen look like test tubes, cylinders, or beakers. The Projector
A 6-ft X 6-ft picture is projected upon the whitepainted sidewall of the lecture hall, using a projector sufficiently powerful (500 watts or more) that the room need not be darkened. Any make or model of projector can be adapted to this technique, some more easily than others. By way of illustration, three adaptations follow: (1) The AcbO-Matic dual-position projector made by the Laboratory Furniture Co., Inc., Mineola, New York. The devices described in this series fit this projector, using the vertical stage only; however, again let it be emphasized that any projector will work. (2) A Master Vu-Graph, made by the Charles Beseler Company, East Orange, New Jersey. Remove the post bearing the lens and head; place the projector on its side. Place the device in front of the stage. Clamp a 12-in. X We are indebted to the National Science Foundation for sponsoring this project (1960-62). Associated with the author were Kenneth V. Jackman (chemistry, physics) and George C. Whiteley, Jr. (biology) of The Hill School; S. Alton Yarian (general science) of the Lakewood, Ohio, H. S.; ttnd Rev. Lanrence McGowm (chemistry) of the Archbishop Stepinac H. S., White Plains, N. Y. Devices in this present series were d e veloped by H. N. Alyea; contributions by the others will appear in later series. The author is also indebted to his three assistants in Princeton, Albert A. Surina, Philip K. Ashby, and Mrs. Lilliae Brescia of Mannehawkin, N. J., who bore with him the trials and tribulations of many prototypes before final decision on any device, and particularly to Mrs. Brescia whose skillful drawings greatly augment the value of the series. 'Far an extensive bibliography on overhead projection see ALYEA, H. N., THIS JOURNAL, 33, A541 (1956); 36, A7534 (1959).
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lournal of Chemical Mumiion
12-in. mirror a t a 45' angle (6 to 3 o'clock position) in front of the device. Fasten the lens and head assembly above the mirror, rotating the head so i t reflects on either the side or the front wall of the classroom. (3) A standard 3'/&1. X 4-in. slide projector. The chemical devices replace the slideholder. This inverts the image, but it can be righted by placing a 10-in. X 10-in. mirror in front of the projector, tipping projector and mirror so the image "bounces off" a t a small angle (projector a t 8 to 6 o'clock position, mirror a t 6 to 4 o'clock). This method was suggested by S. Alton Yarian, of our NSF team. The Devices
The 28 devices are shown in Figure 1. Detailed instructions for making and operating them appear in this issue and will continue in the February through Subsequent articles in May issues of THIS JOURNAL. the series will describe the 1000 experiments possible with these 28 devices, following the same topical sequence as was used in the 1955-56 Tested Demonstration series; e.g., Topic 1 will be Chemical Reactions. Cells. These correspond to large beakers or lecture-jars in macro-demonstrations. Electrical Devices. Includes electrolysis, ionic migration in solution or in gelatin, electroplatimg, and EMF measurements on couples. These devices all fit into electrolytic cell E-1, into which can be plugged a dc source (EZ) or an electrical meter (Me). Gas Devices. These replace the gas generators and pneumatic troughs of macr+demonstrations. Typical experiments follow. In G-1, Zn HCl, catching and testing the Hz evolved. I n G-2, contrast of rate of evolution of Hz bubbles from HC1 granular versus mossy Zn. I n G-3, preparing, collecting, and testing O2 from heated KC103. In 6-4, preparing COI, SOz, HZS,etc., for test purposes. Heating Devices. Typical experiments follow. I n H-1, heating HgO and observing the formation of a Hg mirror. I n H-2, heating one tube while cooling the other as in the equilibrium (red) NzOl (colorless) 2NOz. In H-3, heating one, two, or three solutions, e.g., heating yellow Fe+3to form red colloidal Fe(OH)3. In H 4 , fires and smokes, e.g. Pharaoh's serpents, or with Zn NH4N03 H20. Horizontalizer. This device reflects the light beam up through the solution for showing surface tension effects, Na on water, etc. Measuring Devices. These are for measuring volts or milliamps, (Me), pressures a t atmospheric (Mp-1) or near-vacuum (Mp-2) pressures, temperatures on a gas thermometer (MO-1)or bimettalic thermometer (MO-2), time in seconds (Mt-1) or in seconds-minutes (Mt-2), volumes (Mv) and weight (Mw-1 and Mw-2)
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Figure 1.
Devices for Use in TOPS
CELLS
ELECTRICAL
Holder E - 1
r
Electrodes
Holi-cell
Go5 off
Plotng
Migration
Bctfeiy E-2
GAS
HORIZONTALIZER:
HEAT
MEASUREMENT
Me-voif
Mp-1
MZ-1
MI-)
M"
ELECTRICITY
PRESSURE
TEMPERATURE
TIME
VOLUME
,Mx. 1
WEIGHT
Volume 39, Number I, January 1962
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