INSTRUMENTATION
OUTSTANDING ADVANCE MADE IN HOT PLATE DESIGN AND PERFORMANCE
the outside of the skin, local inhomogeneties are eliminated. The column is encased in a metal jacket fitted with a pressure gauge. Their Uvicord ultraviolet absorptiometer allows the identification of zones in the eluate from chromato graphic and electrophoretic column separations of substances absorbing ul traviolet light of 2537 A. Typical ex amples of such substances are cyclic hydrocarbons, nucleosides and nucleo tides, purines, pyrimidines, proteins and certain peptides, and some enzymes, conjugated fatty acids, hormones, ster oids, and vitamins. The absorptiometer includes a de tachable optical unit containing an in tensity-stabilized, low-pressure mercury lamp, liquid ultraviolet filter, a flow cell of quartz with a 0.09-ml. holdup, a vacuum phototube, and a power sup ply amplifier unit containing lamp volt age stabilizer and amplifier circuits. The output from the amplifier can be fed to a recorder for 10 mv., 100 m v , or 0-1 ma. or to a directly indicating meter. The L.K.B. paper electrophoresis equipment is widely used. In connec tion with the high-resolution buffer salts of the Aronson-Gronwall type serum proteins can be resolved into nine components. We saw several of these instruments in use in the famous Glostrup County Hospital near Copen hagen. Particularly fine conductivity cells with very small holdup are built by L.K.B. These are in the form of a fine capillary spiral for rapid tempera ture equilibration and are fitted with small platinum electrodes. Despite their fragility, they are mounted in molded plastic frames for convenient immersion in a thermostat and form a relatively rugged assembly. Many Americans are familiar with "Science Tools" published periodically by L.K.B. Some very scholarly articles on a variety of topics have appeared. At random we pick a few which have appeared in the past few years. "The Decay of Gadolinium-153," "Useful Simplification of the Method of Least Squares," and "Oxygen Tension (Blood less Determination of Arterial) by Polarography." To keep things interest ing, the April 1960 issue contained a problem—"On the Distribution of Gold Bars among Bank Robbers." The problem was posed in flawless English combined with authentic gangster ter minology. The correct solution re quired Diophantine equations and cor rect answers were received from Portu gal, Scotland, Holland, Germany, the U. S., Australia, and other places!
PRECISION SCIENTIFIC PRESENTS NEW T h e r m - # - P l a t e Hot P l a t e s
Therm - Ο - Plate Available in six sixes with heating surfaces from 5" χ 5" up la 12" χ Μ * . Choice of square or rectangular types in small or large s i » s .
NOW Precision Scientific offers new design features for greatly improved performance together with modern styling. Here are units built for continu ous duty and long service . . . available in a variety of sizes. NOW Precision gives you fully ad justable stepless heat control . . . temperatures maintained as selected . . . repeat settings with accuracy. NOW you benefit from even distri bution of heat with minimum possible temperature differential between center and edges.
Therm-O-Mix Combines an electric hot plate with a magnetic stirrer. Control to 700°F. Even stirring speeds to 1800 R.P.M. Has sepa rate controls. Two sizes with a 5" χ 5" or 7 V i " ν TViu
hnt nlntB > n r f n »
NOW the heat is kept on the heating surface with sides, bottom and controls remaining cool . . . no direct metal-to-metal contact.
NOW four types and eleven sizes to meet every laboratory need . . . standard models . . . stirring-heating models . . . shaking-heating model. . . explosion-proof models.
Therm - Ο - Shake Has all features of a 12" χ 12" Therm-OPfate with a shaking hat plate surface. Temperatures to 800 F. Shaking speed of 200 oscillations per minute. Hot plate and shaking motor controls are separate.
THE ALL N E W
Therm-#-Plate Hot Plates
EXPLOSION PBOOF T h e r m
Write for Bulletin 609 for 12 pages of BUILT
3 7 3 7 W . Cortland Street Chicago 4 7 , Illinois Local offices in Chicago
· Cleveland
·
ANALYTICAL CHEMISTRY
information
BY
PRECISION S C I E N T I F I C CO. · Houston
· New York · Philadelphia
Circle No. 67 on Readers' Service Card 132 A
Ο-Plate
Steam .heated hot plates for hazardous locations. No electricity required. No moving parts. Tempera tures to 2 5 7 F . Steam pressure range, 0 to 60 lbs. Sties 7" χ 22" and 12" χ 12".
PS
· San
Francisco
