FOR THE MICRO-CHEMIST ACCUSTOMED TO THE FINEST!
25 DKOS BUNGE
TWO-PAN RIDERLESS MICRO BALANCE
Faster and more efficient. The conventional rider is replaced by automatic fractional weight loader (1 mg-10 mg) operated by dial on front panel. Auto matic swing-out device lifts pan from resting position to outside weighing compartment for loading. Housing design affords rapid temperature equaliza tion and easy accessibility to pan for positioning absorption tubes. Together with air damping, these features make the 25 DKOS as rapid as single pan competitive models.
Capacity: 30 g Micro Scale: 0 mg-1 mg Sensitivity: 0.001 mg Est. to: ± 0.002 mg Mechanical Weight Selection: 1 mg-990 mg Knife Edges and Planes: Agate The Ultimate in Weighing Precision 0.0000001g (0.1 /ig) with the
BUNGE 25 UM ULTRA-MICRO BALANCE CAPACITY:
SENSITIVITY:
2 mg optical scale 9 mg automatic weight loader 2.5 g built-in tare weights
2.511 g Total
OUTS|DE
LOADING:
IKA UNIVERSAL AUTOMAT MICRO COMBUSTION APPARATUS permits faster and more accurate determinations of C, H, N , O, S and Halogens with controlled temperature to 1200° C. Both heaters are hinged for easier insertion and removal of combustion tube and to provide faster cooling. All controls are on the front panel with separate tempera ture indicators for long and short heaters. The heater ele ments are completely imbedded in ceramic to prevent break age and oxidation. The Universal Automat may be used for semi-micro deter minations by merely interchanging heaters.
SPECIFICATIONS Short heater provides tempera tures up to 1200" C within 8 iiiiriuics. Cnolinn lime from Ι Πι» 1 (o 5 M C in II) minulcs. l-oin 5 ίο . mm per minule.
Pfaltz & Bauer, Inc. EMPIRE S T A T E BUILDING, N E W YORK
CHickering 4-6485
SCIENTIFIC I N S T R U M E N T S · CHEMICALS · BIOLOGICAL STAINS · ESSENTIAL OILS SPECIALISTS IN BECKMAN INSTRUMENT SALES AND SERVICE · MICROSCOPES, BALANCES AND ALLIED EQUIPMENT Circle No. 86 on Readers' Service Card 50 A
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ANALYTICAL CHEMISTRY
of S t a n d a r d s had supplied laboratories not associated with the petroleum in dustry. T h e A P I has 341 compounds avail able as s t a n d a r d s including 294 h y d r o carbons, 38 organic sulfur compounds a n d 9 organic nitrogen compounds. F u r t h e r information regarding these standards, useful for calibrating instru m e n t s and a p p a r a t u s in the research, development, and analytical labora tories of t h e petroleum, rubber, chemi cal and allied industries, m a y be o b tained b y writing: Beveridge J. M a i r , Petroleum Research L a b o r a t o r y , C a r negie I n s t i t u t e of Technology, P i t t s burgh 13, P a . Eight hydrocarbon blends, NBS S t a n d a r d Sample Nos. 592 to 599, and three hydrocarbons certified for density and refractive index, N B S S t a n d a r d Sample N o s . 211, 217, 218, m a y still be purchased directly from the B u r e a u . T h e blends are used for calibrating m a s s spectrometric and other instrumental procedures employed in t h e analysis of gasolines, n a p t h a s , and blending stocks, whereas the three latter s t a n d a r d s m a y be used to calibrate refractometers, picnometers, and density balances, as well as spectrometers. T h e s t a n d a r d s involved in the t r a n s fer and the standards which still can be purchased from t h e Bureau a r e described in S t a n d a r d Materials, Misc. P u b . 241, available for 30 cents from the Superintendent of Documents, U . S. Government Printing Office, Washing ton 25, D . C,
0.1 /ig Estimations to ± 0.01 ιι%
By automatic pan extraction through front panel
Long heater provides tempera tures up to 1200° C within 20 minutes. Cooling time from • 1200" to 180° C in 10 minutes. Short heater travel time variable
NEWS
Improved Glass Dewar Flask A simple, rugged D e w a r flask having a liquid nitrogen cooled radiation shield has been developed b y t h e National B u r e a u of S t a n d a r d s . Liquid helium can be retained u p to 10 hours after an initial filling of 1.2 liters using this new design. Modifications of the basic design— a double-walled glass vessel with a highly evacuated space between t h e walls—have included; silvering t h e glass to reduce heat transfer, placing a radiation shield between the walls, surrounding the double-walled inner flask with an outer flask of liquid n i t r o gen refrigerant, p u m p i n g the refrig e r a n t to further reduce the t e m p e r a ture, and introducing viewing windows. These designs, however, are more bulky a n d less rigid t h a n desired. T h e most promising new design con sists of an inner double-walled flask of which only the u p p e r portion is sur rounded by a liquid nitrogen jacket. Shielding below the nitrogen jacket is
