Need a really accurate model?
Klett . . . Photometers Klett-Summerson Photoelectric
Glass Cell Calorimeter
No. 900-3
New Cenco-Petersen MOLECULAR MODELS
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can be quickly hand assembled without special tools for three-dimensional study of stereochemical and conformational factors and reaction mechanisms. Designed to overcome many shortcomings of earlier model systems, they • are made up of accurate bond lengths ( 1 A = 5 cm). • present precise angles of distortion (to 30°). • can be locked or left free to rotate under stress. • return perfectly to a preset angle. The stereochemist can now directly predict inter atomic distances and bond angle distortion using these true-to-scale models. Designed for t h e rapid and accurate determination of thiamin, riboflavin, and other substances which fluoresce in solution. The sensitivity and stability are such t h a t it has been found particularly useful in determining very small a m o u n t s of these substances.
KLETT SCIENTIFIC PRODUCTS PHOTOELECTRIC COLORIMETERS · BIO-COLORIMETERS G L A S S ABSORPTION CELLS · COLORIMETER NEPHELOMETERS · G L A S S STANDARDS · KLETT REAGENTS
Klett Manufacturing
Co.
179 EAST 87TH S T R E E T , NEW YORK, Ν. Υ. Circle No. 68 on Readers' Service Card
Polyvalent atoms are colored neoprene balls with threaded aluminum inserts placed at the theoretical bond angles. Monovalent atoms are polystyrene with the appropriate bond permanently attached. T h e bonds themselves may be disassembled and rebuilt with other lengths to provide different scale factors. The complete N o . 71306 Cenco-Petersen Set contains 55 monovalent a t o m s , 59 p o l y v a l e n t atoms, 70 bonds and fittings plus extra parts, all in a partitioned metal case. Send for Booklet 315 for detailed informa tion. $295.00
cenco
CENTRAL
SCIENTIFIC
A Division of Cenco instruments Corporation 1708 Irving Park Road · Chicago 1 3 r Illinois Mountainside, N. J. Montreal Santa Ctara 5omervf7/e, Moss. Toronfo L O Î Ange/es Birmingham, Ala. Ottawa Vancouver Houston Cenco S.A., Breda, The Netherlands Tulsa
Circle No. 42 on Readers' Service Card VOL. 3 3 , N O . 3, MARCH 1 9 6 1
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