22A A N A L Y T I C A L C H E M I S T R Y

B E C K M A N P H O T O E L E C T R I C

QUARTZ SPECTROPHOTOMETER AVAILABLE FOR IMMEDIATE SHIPMENT FROM OUR STOCK

A, Wavelength Scale; B, Built-in Electronic Indicating Meter; C, Slits with precision adjustment; D, Light Source; E, Compartment for two Phototubes; F, Holder for four 10 mm Absorption Cells; G, Filter Slide; H, Compartment for Absorption Cells: .1, Phototube Selector;

and K, Switch for checking dark current.

QUARTZ SPECTROPHOTOMETER, Beckman Photoelectric. A self-contained unit with which a wide variety of research and control work can be conducted with convenience, speed and precision. Consisting of a quartz monochromater, with light source, holder for absorption cells, twin phototubes and built-in electronic meter for translating phototube currents into direct readings of percentage transmission and density. See Cary and Beckman, "A Quartz Photoelectric Spectrophotometer," Journal of the Optical Society of America, Vol. 31, No. 11 {November, 1941), p. 682.

Monochromator. Autocollimating type, with 30° quartz marked " . 1 " provides a ten-fold expansion of the trans-prism of selected crystal which provides high dispersion in mission scale for more accurate readings on solutions below the ultra-violet. Wavelength scale approx. 100 cm long, 10% transmission. readable and reproducible to 0.1 mmu in the ultra-violet and to 1.0 mmu in the red, with a scale accuracy of 1 mmu. L i g h t Source. A standard 32 c. p. 6-volt, tungsten lamp Optical parts rigidly mounted in a massive heat-treated serves as a light source for the range 320 to 1000 mmu. iron block within a dust-proof steel case. A hydrogen discharge lamp is furnished for use in the ultra­

violet range below 320 mmu. Slits. Protected by quartz windows, with stray light ef- Sample Holders. Absorption cells are accommodated in

fects reduced to a minimum. Simultaneously and continu- a r e m 0F

v a b l e h o l d e r w h i c h i s i n s e r t e d in a light-tight com-ously adjustable from 0.01 to 2.0 mm by a precision mecha- p a r t m e n t a n d i s o p e r a t e d from the front of the instrument nasm. Slits can not be damaged by closing too far. Full £ m e a n s o f a s M i r o d C e l l s a n d h o l d e r s a r e a v a i i a b l e scale reading with nominal band width less than 2 mmu over f ^ 1Q 2 Q 5 0 a n d 1 0 Q m m H i d l e n g t h g . all but the extreme ends of the spectrum.

Phototubes. Two phototubes are furnished in a compart-Electronic Indicating Meter. A built-in potentiometer ment which adjoins the cells. A sliding rod brings either

and electronic amplifier makes possible direct readings in tube into position and simultaneously switches the electrical percentage transmission and density. The switch position connections.

9101-A. Quartz Spectrophotometer, Beckman Photoelectric, Model DU, range 320 to 1000 mmu, as above described, with 6-volt tungsten lamp in detachable housing, one each ultraviolet-sensitive and caesium-oxide phototubes, matched set of four square fused Cores glass absorp­tion cells for 10 mm liquid depth with covers made of Pyrex brand glass, and 4-place holder. With dry cells for operating the meter but without 6-volt storage battery for operating the tungsten lamp and electronic tubes. Overall dimensions 30 inches long X 8 inches high X 9 inches wide; net weight 80 lbs.; shipping weight 110 lbs 950.00

9101-B. Ditto, Model DUV, range 220 to 1000 mmu, identical with above but with the addition of accessories for measurements in the ultraviolet region 320 to 220 mmu consisting of one pair of matched fused silica absorption cells for 10 mm liquid depth, hydrogen discharge lamp and power supply unit, 115 volts, 50/60 cycles, a .c , for maintaining the discharge at constant intensity. Shipping weight 165 lbs.

1,250.00

I M o r e de ta i l ed i n f o r m a t i o n r e g a r d i n g a b o v e a n d Flame P h o t o m e t e r . Diffuse Ref lectance and F l u o r e s c e n c e A t t a c h m e n t s sent u o o n reauest .

ARTHUR H. THOMAS COMPANY Π Ε . I M I L . — n n U L b S H L L · - t A r W n ·

LABORATORY APPARATUS AND REAGENTS WEST WASHINGTON SQUARE, PHILADELPHIA 5, PA., U .S .A .

Cable Address "Balance," Philadelphia