REPORT
GL50 À BENCH GLASS LATHE for professional
or occasional
glassworking
This unit Is durable a n d compact requiring only 2 ' χ 3 ' bench a r e a . . . can hold tubing from 0-64 mm through spindle a n d up to 6 " o.d. on the ex clusive contour chucks. Complete, ready to operate.
Price $ 6 7 5 . 0 0
IDEAL FOR PHYSICAL, CHEMICAL, BIOLOGICAL AND ELECTRONIC LABORATORIES A With NEW CONTOUR CHUCKS, two independently working sets of ^ slim self-centered jaws permit, for the first time, chucking and c e n t e r i n g of a v a r i e t y of shapes and sizes. GL50 FLASK HOLDER W with asbestos covered Steel Fingers. Universal self-center ing; permits mounting in head or tailstock up to 6 " o.d.; accepts blowhose and swivel. BURNER CARRIAGE holds lathe f i r e or one or t w o hand torches.
ASK YOUR
DEALER FOR DETAILS.
BETHLEHEM APPARATUS COMPANY, INC.
will be a signal of 0.001 megacycle per second = 1000 cycles per second, which is in the audio range. This beat, or heterodyne frequency, can be measured with a precision of one cycle per second or better by comparing it with the output of a variable audio frequency oscillator. Thus, heterodyning permits a high frequency signal to be greatly re duced in frequency by a precisely known amount, with a consequent improvement in the sensitivity with which small changes in the original frequency can be detected. Sen sitivities of 1 p.p.m. are common with this technique, and parts per billion and better have been ob tained. The frequency comparison of the beat signal with the audio generator is very conveniently obtained by observing the Lissajous figures pro duced on an oscilloscope when one of these signals is introduced on the horizontal deflection plates, while the other is introduced on the vertical deflection plates.
HELIERTOWN, PA. Circle No. 7 on Readers' Service Card
O t h e r T y p e s of
Low absorbency protection water absorption by weight is less than 0.20% in Â8 hours
Oscillators
The preceding summary is not in tended as a comprehensive treat ment of the subject of oscillators. Many useful circuits have not been mentioned, and much important de tail has been left out of the dis cussion of those few circuits which have been included. The principal objective has been to show the role played by oscilla tors in present-day analytical work, to make clear some of the basic principles involved in the generation of sustained oscillations, and to call attention to a few of the unique potentialities of these devices for the solution of experimental prob lems. Bibliography
ALBERENE
for 75 years the only perma nently satisfactory material for chemical laboratory table tops, shelving, sinks, splash backs, drain boards and fume hoods. Prompt delivery. ALBERENE S T O N E - A DIVISION OF THE GEORGIA M A R B L E COMPANY. For FREE l i t e r a t u r e and t e c h n i c a l assistance address: THE ALBERMAR COMPANY, 386 PARK AVE. SOUTH, NEW YORK 16, N. Y., DEPT. C.
STONE
Circle No. S on Readers' Service Card
42 A
·
ANALYTICAL CHEMISTRY
Evans, R. N., Porter, C. B., "Experi mental Basic Electronics," McKnight and McKnight Publ. Co., Bloomington, 111., 1958. Ladd, M. F. C , Lee, W. H., Talanta 4, 274 (1960). Miiller, R. H., Gannan, R. L., Droz, M . E., "Experimental Electronics," Pren tice-Hall, New York, 1942. Rider, J. F., "The Oscillator at Work," John F . Rider Publ., Inc., New York, 1940.
