NEW PRODUCTS FOR ANALYSTS

NEW PRODUCTS FOR ANALYSTS Equipment, Apparatus, Instruments, Reagents, Materials Gelometer

Burrell Corp. is now offering the Castor Gelometer, an instrument designed for determination of gelation time or stability of polyesters and phenolic materials. Gel tests can be run quickly and easily at various temperatures with the self-contained instrument, according to the manufacturer. An oscillator sensitive from 1 It--""' 5000 to 50,000 centipoises automatically stops a timer when a desired viscosity range is reached. The unit is available in two models: with calibrations in seconds or tenths of minutes for gelation tests, and with calibrations in tenths of minutes or minutes for stability tests. Both types are

equipped with 4-digit counters. A constant temperature bath with a range from ambient to 212° F. is furnished separately. 1 Scintillation Spectrometer

Atomic Instrument Co. is marketing a single-channel scintillation spectrometer designed for analysis of various gamma-emitting radioisotopes, whether they occur singly or in mixtures or compounds. The Model 513 spectrometer is a complete assembly, including an external well scintillation detector and a cabinet housing a shielded linear amplifier, differential pulse height analyzer, preset time scaler, and high voltage supply. The scintillation detector incorporates a sodium iodide well crystal, photomultiplier, built-in preamplifier, and lead shielding. Use of the well crystal is claimed to provide high counting efficiency for comparatively low level

Thermometers In Stock for

mmediate Delivery Ranges a n d Immersion Lengths to meet praetiesiSiy e v e r y need.

For Complete Listing of Thermometers W r i t e Dep't F

ACE GLASS INCORPORATED VINELAND Specialists

to

NEW Industry

and

JERSEY Research

gamma radiations. The shielding around the detector- reduces background counts to minimum levels. Solid crystals of varying thicknesses may be substituted for the well crystal for high encrg5^ radiations and spectrometry involving larger solids. A scintillation probe may be added, or flow, proportional or neutron counters substituted for the well detector. 2 V a p o r AmnaSysls A p p a r a t u s

A simple, portable apparatus for the analysis of multicomponent mixtures of gases or volatile liquids is now in production by The Perkin - Elmer Corp. B a s e d on gas chromatography, the Vapor Fractometer operates by fractional separation of vapors by means of a partition column. if The instrument can be used for routine analysis of mixtures of gases or low boiling liquids. It may also be used for separation of unknown components from a mixture for qualitative analysis by other means. Time for analysis varies from Va to 5 minutes per component. Reproducibility is claimed to be better than 1 / 2 %. Complex mixtures can be handled and, in most cases, the accuracy with which trace components can be determined is independent of the concentration or nature of the other components present. Any mixture having boiling points up to 250° C. may be separated by the instrument. As little as 1 mg. of sample per analysis is required. The Vapor Fractometer consists of two interchangeable 4-foot folded partition columns which may be used individually or in tandem, a special thermistor-type thermoconductivity cell as a detector, and sampling and temperature controls. The partition columns are mounted in an insulated chamber which may be held at any temperature up to 150° C. The apparatus weighs less than 50 pounds and measures 30 X 20 X 12

LOUISVILLE, KY., 639-41 SOUTH HANCOCK ST.

For further information, see coupon on For further information, circle number 42 A on Readers' Service Card, page 39 A

42 A

page 39 A

ANALYTICAL

CHEMISTRY

NEW PRODUCTS

age and contamination. This membrane can be readily opened with a special blade supplied with each bottle. The nonwetting properties of polyethylene are said to facilitate the transfer of the bottle's contents. Stansols can be stored indefinitely without deterioration until opened and used, says Chicago Apparatus. 4

inches. The output of the detector can be connected directly to any standard 10-mv. recorder for making a permanent record of an analysis. 3 Standard Solutions

A wide variety of ready-to-use standardized solutions are being marketed by Chicago Apparatus Co. The solutions, called Stansols, are claimed to he accurate to 1 part in 1000. They are packaged in polyethylene bottles, with a heat-sealed membrane under the screw cap to eliminate spill-

Spectrographs Standards

A set of eight low-alloy steel spectrographic standards issued by the British Bureau of Analyzed Samples, Ltd., is

being distributed in the United States by Jarrell-Ash Co. The standards are in the form of rods 1 / 2 inch in diameter and 6 inches long. They are packaged in a cardboard box and accompanied by individual certificates. Range of composition for the seven elements certified in the standards is: Silicon Manganese Nickel Chromium Molybdenum Vanadium Copper

0.013-0.81% 0.016-1.4% 0.048-5. 15% 0.044-3.07% 0.007-2.34% 0.034-0.80% 0.090-0.49% 5

Rack for Drying Graduated Cylinders

IT

COSTS

SO

LITTLE

Up to 25 graduated glass cylinders can be dried and stored at one time on a rotating support rack built of steel rods and coated with neoprenc rubber. Cylinders are hung in an inverted position so that solvents drain quickly into an aluminum pan below.

TO

Safeguard purity Percentage-wise, yes, a n d d o l l a r - w i s e , too, the m o n e y a n y l a b o r a t o r y spends f o r l a b o r a t o r y t u b i n g a m o u n t s to little. But the cost of using i n f e r i o r q u a l i t y t u b i n g can be e x t r e m e l y h i g h . C o n t a m i n a t i o n of a single solution m i g h t cost m o r e t h a n a year's s u p p l y of t u b i n g . That's basically w h y l a b o r a t o r i e s the w o r l d over use T y g o n plastic t u b i n g — insist on Tygon — refuse to accept t u b i n g sold as " j u s t as g o o d as T y g o n . " For l a b o r a t o r y technicians k n o w T y g o n is the one t u b i n g completely " n e u t r a l " — neither affecting nor b e i n g affected b y v i r t u a l l y a n y solution they m i g h t use.

The rack, which is marketed by Arthur S. LaPine & Co., accommodates cylinders in sizes from 5 to 1000 ml. All are readily accessible, as the support revolves for convenient selection of the size desired. Height of the unit is 18 inches; diameter of the drain pan is 20 inches. 6

A d d to this o u t s t a n d i n g a n d p r o v e n q u a l i t y : Glass-clearness, string-like flexi b i l i t y , u n m a t c h e d c o u p l i n g ease, a n d a n a v a i l a b i l i t y in a r a n g e of sizes to meet e v e r y need — a n d it's easy to see w h y T Y G O N is the accepted s t a n d a r d of l a b o r a t o r i e s e v e r y w h e r e . ASK

FOR — I N S I S T

Balance

ON —

TYGON at

your

favorite supply

laboratory

house

o r Write direct to U. S. Stoneware

· Akron 9 , Ohio 374D

For further information, circle number 44 A on Readers' Service Card, page 39 A

44 A

A technical balance of 1-kg. capacity having a chain loading device that eliminates use of fractional weights is being sold by Arthur S. LaPine & Co. Use of two chains, one attached to each arm of the beam, is said to permit the beam to be raised into weighing position without its equilibrium being upset. The Reyers-Rapid balance need not be arrested when fractions of grams are being added or removed by means of the knob-operated chain loader. An indicator shows the value of the weight For further information, see coupon on page 39 A ANALYTICAL

CHEMISTRY

NEW PRODUCTS being added. T h e chain loading device is adjustable t o 10 mg., t h e sensitivity of t h e balance. 7

end point t h a t is as sharp and sensitive as t h a t of starch. T h e material re­ quires no preparation for use. I t does not deteriorate a n d is unaffected by bacteria or molds. 8

l o d i m e l r y Indicator T h y o d e n e — a dry, white, stable, or­ ganic powder t h a t is soluble, in water a n d can be used to replace starch solu­ tions as a n indicator in iodimetry—is now being distributed in t h e United States a n d C a n a d a b y Fisher Scientific Co. T h y o d e n e is reported to yield a blue

H u m i d i t y Cabinet

diameter and 12 inches high and provid­ ing i y 4 cubic feet of working area. T h e jar is placed on a welded stain­ less steel cabinet which houses wet and dry b u l b controls, motor, blower, cool­ ing coil, a n d solenoid valve. T h e r e are no doors t o require sealing. A 1 / 2 -inch a p e r t u r e is provided for thermocouple leads or for recording h u m i d i t y .

A relatively inexpensive, mechanical convection, temperature-controlled rela­ tive h u m i d i t y cabinet is being pro­ duced b y Blue M Electric Co. T h e cabinet makes use of a n inverted borosilicate glass jar measuring 16 inches in

PUFF 'heap big hurry for special glass" Happy with his last shipment of PYREX peace pipes, this fellow has dreamed up some new uses for special apparatus — and knows where to come for it. People over in our Special Ap­ paratus Department are used to unusual orders. They don't waste time clucking tongues, because they've seen just about everything. They'll take some tortured memo­ ries, give them a few new twists, add a lot of skill and another piece of special apparatus will be on the way. To him, to Mars, or to you. You'll get PYREX brand glass No. 7740, too, or if you want something more special, you can get VYCOR brand No. 7900, with its higher temperature limit. For "ordinary" specialties, con­ sult our brand new 116-page cata­ log, "Custom Made Laboratory Glassware by Corning." Just send in "wampum" below. CORNING

GLASS

WORKS

CORNING, N . Y .

Corning means research in Glass

Relative h u m i d i t y can be controlled from 2 0 % to near saturation. Accuracy of t h e wet bulb is within ± 2 % a n d d r y b u l b accuracy is ± 1 ° F . from a m b i e n t to 70° C , says t h e m a n u f a c t u r e r . 9 Recording Spectrophotometer By use of optical elements of increased ultraviolet efficiency in t h e prism grat­ ing double monochromator, Applied Physics Corp. has extended t h e range of its C a r y Model 14 recording spectro­ p h o t o m e t e r t o 1900 A. a n d even shorter wave lengths. T h e improved range will permit analysis of a n u m b e r of compounds— including ketones, alcohols, mono-olefins, and aromatic materials—not a d a p t ­ able to ultraviolet spectrophotometry on s t a n d a r d instruments, according to the company. 10 A P I Standard H y d r o c a r b o n s M o s t recent additions to t h e series of American Petroleum I n s t i t u t e standard samples of hydrocarbons available from t h e Petroleum Research L a b o r a t o r y of Carnegie I n s t i t u t e of Technology are t h e following c o m p o u n d s : 3,3-Dimethyl-l -pentene 2,S-Dimethyl-irans-3-hexene 2-Methyl-3-ethyl-l-pentene

11

CORNING GLASS WORKS 52-6 Crystal Street, Corning, Ν . Υ. Please send me your new catalog C A - l î "Custom Made Laboratory Glassware by C o r n i n g . " Name

Title

Company Address

"inj^

City

,

Zone

State

For further information, circle number 46 A on Readers' Service Card, page 39 A

46 A

Single Crystal Camera A single crystal cylindrical camera designed t o t a k e oscillation a n d rotation photographs of single crystal specimens on a stationary cylindrical film has been announced b y N o r t h American Philips Co., Inc. For further information, see coupon on page 39 A ANALYTICAL

CHEMISTRY

NEW PRODUCTS T h e technique of rotating the crystal permits the structure of crystal speci­ mens to be determined t h r o u g h analysis of position a n d intensity of spots on the film. Horizontal spot p a t t e r n s reveal t h e n a t u r e of the lattice unit cell. In t h e new cylindrical camera, an x-ray beam impinges upon a single crystal which occupies a specialized orientation with respect to the beam. T h i s pro­ duces diffracted rays. When the crystal is rotated, reflections for each of the major axes of t h e single crystal are recorded for a wide range of glancing angle values. These reflections can be used in determining cell constants, identifying space groups, and locating a t o m positions. T h e i n s t r u m e n t is designed for m o u n t ­ ing on t h e camera t r a c k of t h e Norelco diffractometer and m a y be used in con­ junction with a Norelco flat plate camera. 12

T O ANALYTSCAL CHEMISTS if y o u are a n analytical chemist, this h a n d y , desk-size S&S Filtra­ tion C h a r t belongs in your -ι bora tory. Analytical laboratories h a v e long b e e n familiar w i t h s t a n d a r d i z e d , h i g h - q u a l i t y S&S A n a l y t i c a l Filter P a p e r s . N o w , h e r e is c o m p l e t e d a t a on the relative retention values of S&S Analytical Filter P a p e r s , a n d other b r a n d s , in convenient size for r e a d y reference. This d a t a makes it possible to tell a t a glance w h i c h g r a d e of p a p e r to select for a given analysis. Send for your valuable, free S&S Filtration C h a r t . Act n o w ! Use t h e h a n d y c o u p o n below!

A four-unit power supply for use with paper electrophoresis a p p a r a t u s is avail­ able from Labline, I n c . T h e Power-Pak unit has a capacity of 50 m a . a t 500 volts, which is adjustable t h r o u g h o u t the entire range.

THIS

COUPON

Company

TODAY

City

State

D Β 0 Q

Circle No. 48 A on Readers' Service Card, page 39 A

48 A

T h e current and voltage regulator circuit is designed so t h a t there is no voltage change on changes in current consumption from 0 to 50 m a . Changes in fine voltage do not affect the o u t p u t of the unit. On the panel board of the a p p a r a t u s are a milliammeter, voltmeter, line fuse, load fuse, rheostat control for current, line switch, load switch, and four sets of plug-ins for connecting with four paper electrophoresis migration chambers. 1 3 V a c u u m Pumps

D

Address

1O% REPLACEMENT ALLOWANCE

Constant T e m p e r a t u r e Replacement Items BATHS Carbon Residue, Conrad son, ASTM D524 Demulsibuity of Lubricants, Appendix 6 General Purpose, Glass, A q u a r i u m Type General Purpose, Glass, Economy Model General Purpose, Glass, W i t h Motor Stirrer General Purpose, M e t a l , W i t h Motor Stirrer General Purpose, M e t a l , Rectangular, Freas General Purpose, M e t a l , Rectangular, Freas W i t h M o t o r Stirrer O x i d a t i o n of Grease, Norma Hoffman, ASTM D942 O x i d a t i o n of Lubricants, Indiana O x i d a t i o n of Lubricants, Sligh O x i d a t i o n of Transformer O i l , ASTM Γ>1314 O x i d a t i o n of Steam Turbine O i l , ASTM D943 Rust Prevention Tester, ASTM D665 Serological Serological, Clinical Serological, Army Medical Soil Hydrometer Jar, ASTM D422 Vapor Pressure, Reid, 3 Bomb M o d e l , ASTM D323 Viscosity, Kinematic, DeLuxe M o d e l , ASTM 0664 Viscosity, Sayboit, 2 tube M o d e l , ASTM D664 Utility—Serological Warburg W a r b u r g , Refrigerated CABINETS Corrosion Test, A r m y , Navy, H792 H u m i d i t y , Steel, enameled finish H u m i d i t y , Stainless Steel finish Low Temperature C I R C U L A T I N G SYSTEM Temptrol FURNACES Carius Combustion Tube, steel, enameled finish, 4 tube Carius Combustion Tube, Stainless Steel finish Rolf Tester, M i l - S h e l , G l 0924 Wheel Bearing Tester, ASTM D1203 I N C U B A T O R S , O V E N S , STERILIZERS

CARL SCHLEICHER & SCHUELL CO. Dept.AC-6,ΚΕΕΝΕ, HEW HAMPSHIRE

Send me your F R E E Π S&S Filtration Chart Π S&S Ultra Filter Catalog Name

PRECISION

Muffle GREASE TESTING APPARATUS (Other than Baths)

S & S ULTRA FILTERS S&S d u a l - p u r p o s e u l t r a filters — smooth-surfaced membranes P o s " sessing extremely uniform microstructure—are ideal for filtration of colloids, proteins, and micro-organ­ isms, as well as dialysis and osmosis. Mail coupon below for your free S&S Ultra Filter Catalog. MAIL

P o w e r Supply

Here are the

A new line of mechanical vacuum p u m p s t h a t is said to operate quietly a n d with practically no vibration has been developed b y Central Scientific Co. I n addition to its quiet operation, t h e H y v a c 4 p u m p is reported to h a v e increased pumping capacity per cubic For further information, see coupon on page 39 A

Gravi+y Convection, Freas, Steel, enameled finish Gravity Convection, Freas, Stainless Steel finish G r a v i t y Convection, Thelco, Steel, enameled finish Asphaltic Compounds, ASTM, Steel, enameled finish Asphalfic Compounds, ASTM, Stainless Steel finish Coal Moisture, ASTM D271 C o n d i t i o n i n g , G r a v i t y , Convection, Freas, Steel, enameled finish C o n d i t i o n i n g , Mechanical Convection, Freas, Steel, enameled finish General Purpose, Gravity Convection, Freas, Steel, enameled finish General Purpose, Gravity Convection, Freas, Stainless Steel finish General Purpose, Mechanical Convection, Freas, Steel, enameled finish General Purpose, Mechanical Convection, Freas, Stainless Steel finish General Purpose, Mechanical Convection, Freas, Steel, enameled finish. Explosion Proof General Purpose, Mechanical Convection, Freas, Stainless Steel finish. Explosion Proof Vacuum, Freas, C y l i n d e r 9 x 9 " , Steel, enameled finish Vacuum, Freas, Cylinder 9 x 9 " , Stainless Steel finish Vacuum, Freas, Cylinder 9 x 1 8 " , Steel enameled finish Vacuum, Freas, Cylinder 9 x 1 8 " , Stainless Steel finish General Purpose, G r a v i t y Convection, Freas, Hazard Safe, Steel, enameled finish General Purpose, G r a v i t y Convection, Freas, Hazard Safe, Stainless Steel finish General Purpose, Mechanical Convection, Freas, Hazard Safe, Sfeel, enameled finish General Purpose, Mechanical Convection, Freas, Hazard Safe, Stainless Steel finish General Purpose, G r a v i t y Convection, Thelco, Steel, enameled finish General Purpose, G r a v i t y Convection, Thelco, Transite Vacuum, Thelco, Rectangular Gas Heated (Sterilizer)

Precision Scientific Company 3725 West Cortland Street ·

ANALYTICAL

Chicago 4 7

CHEMISTRY

VISCOSITY a factor in your

product?

SAVE MONEY WITH f THEHOEPPLER f Here's an instrument that pays for it­ self over and over again! H o w ? By assisting in product development and manufacture — and by eliminating costly e r r o r s i n viscosity control. Operating o n t h e falling-ball principle, the H o e p p l e r Viscosimeter has an accuracy of 0 . 1 % t o 0 . 5 % . Even gases as well as liquids, oils, plastics, syrups, viscous tars, etc., can be measured. Only a small sample (30cc) is required, a n d results are consistent and reproducible. T h e Hoeppler Viscosimeter is n o w serving manufacturers in many fields — food, chemical, ceramic, plastic, etc. It belongs i n any laboratory where viscosity is a factor i n the manufacture o r sale of a product. Write for Bulletin HV-303, which gives complete details

NEW PRODUCTS foot of space occupied. I t produces a free a i r displacement of 70 liters per m i n u t e and a n ultimate v a c u u m of 0.1 micron. T h e unit can p u m p from atmospheric pressure t o ultimate pres­ sure in less t h a n 5 minutes. 14 Binders for Spectrograms For p e r m a n e n t filing and preservation of infrared a n d ultraviolet spectro­ grams, Spectra-Bind Associates is of­ fering s t u r d y canvas-covered doublepost slot lock binders. T h e binders provide readily accessible reference files for original spectra from Baird, Beckman, Carey, a n d PerkinElmer spectrophotometers. T h e y are designed for holding spectrogram sheets covering t h e 2- t o 15-micron infrared spectral range and t h e 200- to 750-ηΐμ ul­ traviolet a n d visible regions. Binders of other size also can be supplied. 15

FALLING BALL

Manufactured by FISH-SCHURMAN CORP. 72 Portman Road, New Rochelle, Ν. Υ.

Fish-Schurman For further Information, circle number SO A-1 on Readers' service Card, page 39 A

New GIANT Poly-Funnel

Karl Fischer Methanol M e t h a n o l containing less t h a n 100 p.p.m. water for u s e i n K a r l Fischer moisture determinations has been added to Mallinckrodt Chemical W o r k s ' line of analytical reagents. T h e new material is claimed t o pro­ vide a satisfactory vehicle for samples and t o reduce the consumption of Karl Fischer reagent used t o pretitrate water content. I t is furnished in 30-pound 16 drums. C 14 -Labeled Fatty Alcohols Cetyl-1-C 1 4 alcohol and stearyl-1-C· 4 alcohol have been added t o t h e list of carbon-14-tagged compounds offered b y Nuclear I n s t r u m e n t and Chemical Corp. T h e y can b e used for synthesizing labeled detergents or in metabolic studies. T h e compounds are available in package sizes of 1, 0.5, and 0.1 millicurie under regular Atomic Energy Com­ mission licensing procedures. Specific activities are approximately 1 millicurie per millimole. 17 Organic Chemicals

blean, durable, light-weight, chemically resistant polyethylene makes the most practical and efficient f u n n e l s . . . and here is one that really is BIG enough to answer every pouring need! The new Nalgene Giant Poly-Funnel is 1 1 " in diameter with the same over-all height (11") and a 3 " stem. Minimum wall thickness is Vs", ribbed for extra strength inside and out. Compared with similar funnels of the same size and quality, you'll find it surprisingly inexpensive . . . only $8.50 each. Catalog No. 1236

The Ask /or our newest bulletin C455 on Nalgene Polyethylene ware.

NALGE CO., Inc. R O C H E S T E R 2 , N E W YORK

For further information, circle number SO A-2 on Readers' Service Card, page 39 A

50 A

Among 10 new organic compounds recently added t o t h e chemicals avail­ able from Distillation Products I n d u s ­ tries is 4,5-dihydroxy-w-benzenedisulfonic acid disodium salt, a sensitive re­ agent for iron a n d t i t a n i u m t h a t can be used t o determine b o t h metals sepa­ rately in a single solution. Other recent additions t o t h e line of E a s t m a n organic chemicals include: 3-Amino-l-propanol 2-w-Butylaminoethanol

For further information, see coupon on page 39 A ANALYTICAL

CHEMISTRY

MANUFACTURERS' LITERATURE

Dipropionin 1-Docosanol N-Ethyl-n-butylamine Methyl benzenesulfonate Nitrocyclohexane Pyromellitic acid Vinyl butyrate

LEITZ 18

AND

POLARIZING

M I C R O S C O P E S

A C C E S S O R I E S

Pressure and Vacuum Gage

A new wide-range Zimmerli gage has been developed by Scientific Glass Ap­ paratus Co., Inc. The gage is intended for use at pressures up to 370 mm. of mercury above atmospheric, and for the full barometric range of reduced pres­ sures. The apparatus has long glass mem­ bers and is provided with a stopcock assembly to facilitate switching between measurements of absolute and of dif­ ferential pressures. 19

1. M o d e l

SY

Research instrument with synchronous rotation of polarizer and analyzer with fine adjustment (0.001mm) on double ball bearings.

2. Model

AM

Universal Research Microscope for transmitted and reflected polarized

Electric Manometer

light with focusing stage.

An electronic manometer for indicat­ ing the pressure of a contained gas in inches of mercury is being produced by Victoreen Instrument Co. The instru­ ment is for use with Victoreen VM-1 terminals, which are installed in the gas chamber. A constant current at high voltage is passed across the terminals. Pressures can be measured over a range of 3 to 7 inches of mercury. 20

3. Model

MOP

Ore Microscope for reflected or transmitted polarized light. Focusing stage permits accommodations of large objects. Coated optics.

MANUFACTURERS' LITERATURE

4. Model

HIM

Most popular student and laboratory chemical microscope. It permits the use of a

Laboratory Furniture. Catalog of 16 pages lists specifications and prices of laboratory furniture, .fixtures, acces­ sories, and special units. The Chemical Rubber Co. (Cat. 100). 21

complete line of polarizing accessories.

S. U n i v e r s a l

Table Tops. Folder of 4 pages de­ scribes advantages of chemical-, heat-, and shock-resistant sheet material for laboratory table tops and other work spaces and equipment. Johns-AIanville (Colorlith). 22 Stainless Steel Equipment. Catalog of 16 pages covers stainless steel sinks, tanks, trays, and accessories for labora­ tory, chemical processing, and photo­ graphic applications. P&H Sales Corp. (Cat. SE55). 23 pH Electrodes. Four-page folder gives reference table covering 60 glass, metal­ lic, and reference electrodes for Beckman pH meters. Will Corp. 24

and rapid determination of optical properties.

E. L E I T Z , I N C . Distributor oj the world-famous product* of Ernst Leitz, JVelztar, Germany

Ε . L e l t z , I n c . , Dept. AC, J,68 Fourth Avenue, New York 1β, Ν. Y. Please send me your brochure on the

For further information, see coupon on page 39 A V O L U M E 2 7, NO. 6, J U N E

1955

_______

Name

,

Company Street

Electron Microscopes. Booklet of 22 pages covers design, specifications, and uses of electron microscopes. Radio Corp. of America. 25

Rotating

s t a g e For accurate

City

„. , State

.

For further information, circle number 51 A on Readers' Service Card, page 39 A

51 A