NEW BOOKS analytical methods, J. D. McCallum; and an instrument for preparative GC, P. A. Bushong. A new approach is outlined by H. A. Szymanski in which a mixture of two solid support media, one of which is susceptible to induction heating, is used in GC columns. The advantages of this method are discussed. A panel discussion consisting of questions and answers is also included in this book.
needle valve hose cock for fine control of rare gases and standard services
Confidence Interval Lengths far Small Numbers of Replicates.
Raymond H. Pierson. v + 37 pages. Mr. R. H. Pierson, 3Sl.'f N. Angeles Forest Hwy., Palmdale, Calif. 1963. $1.75. Paperbound.
fine, regulated control for any specific service withstands exceptionally high pressure and leakage tests (independent laboratory report on reques
floating stainless steel needle resists corrosion and wear packless sliding seal construction heavy duty chrome plating and construction available in various styles for all installations ;fine, regulated 'control for standard or ::;ex0tic elements calls for a highly special'•• iized, leak-proof fixture to do the job. This I&S Lab-flo needle valve hose cock was sespecially developed to. function perfectly ;even under unusually high pressures. : Built-in safety margins and high quality lerfsrmance exemplify the complete inte|fated line of lab-flo laboratory service fixtures, 1^ you haver. a "particular service : (problem in your laboratory, Lab-flo may fiaveJrt all likelihood already solved it. • We invite your inquiry on specific applications." Needle Vaive Hose Cock Bulletin \MQ> 40IL or:'complete LaMlo Catalog No. r: lO-Aiavaiiabie on request.
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iM-tiS SPEC MANUAL This:::dynamic: LAB-Pi.0: planning '"uld*i; oYijviiies all of the newest rawftifsiaM data: for roughing-jn or spjebtf^ing a soniptete laboratory servibe fixture system,, or any part ..of Hi Write or call for your pergonal, registered copy.
f
Refer to 1963 Sweet's Catalog, Code 35b Ta
T&S BRASS A N D BRONZE W O R K S , I N C . 128 Magnolia Ave.,. Westbury, L I., N Y. Area Code: 516/EOgewood 4-5104 NATIONWIDE LAB-FLO SALES AND STOCK COVERAGE SERVICE FIXTURES* HOSE COCKS* REMOTE CONTROLS • COMBINATION FIXTURES • RECEPTACLES Circle No. 1 on Readers' Service Card
72 A
ANALYTICAL CHEMISTRY
These tables should prove useful to scientists or engineers who have to determine the length of a confidence interval, the precision required of a test method, or the amount of replication required when any two of these three quantities (acceptable confidence interval length, precision, or number of replications) are known or decided upon. Three tables are presented at several confidence (probability) levels. Table I (at 99, 98, 90, and 80% probability levels) provides factors for rapid calculation of the one-half length of the confidence interval for a population mean under a variety of conditions depending upon the reliability of the value for standard deviation that is available. Table II (at 99, 95, and 90% probability levels) gives direct reading values for one-half the length of the confidence interval when a reliable value for the population standard deviation is available. Table ITI (Appendix) provides a guide (at 5 probability levels) for rejection of outliers (suspected deviate values in a series of reiilioat.es) on an a posteriori basis.
A G u i d e t o t h e Scientific a n d Technical L i t e r a t u r e of Eastern E u r o p e .
Printing and Publications Office of the National Science Foundation, 1951 Constitution Ave., Washington 25, B.C. 19Ci3. No rout. This guide is intended for use by scientists, librarians, and students, and contains information of the announcement, availability, procurement, and translation of the scientific and technical literature of Albania, Bulgaria, Czechoslovakia, Hungary, Poland, Romania, and Yugoslavia. Information is given on how to obtain the publications and what literature is available in English. A 50-page appendix contains an annotated list,
THE MIXER YOU CAN USE ANYWHERE This mixer is safe. Its m o t o r is totally enclosed, explosionproof — approved by U / L for Class I, Group D, and for Class II, Groups E, F and G, service. It's a heavy-duty mixer, designed f o r continuous operation. Using it, you can quickly bring 50 gallons of low-viscosity fluids to uniformity, or mix smaller quantities of high-viscosity fluids. It's a good t o o l for suspending solids, dispersing gas or studying mass transfer and heat transfer. Put it into a pilot-plant setup and you can derive accurate mixing data for scale-up c o m p u t a t i o n s . It's a LIGHTNIN Mixer—Model XP. Like all LIGHTNIN Mixers, it's fully guaranteed. The 1/20-hp m o t o r t u r n s the 24inch stainless steel shaft and 2 % - i n c h propeller at a constant 1750 r p m . Bearings t h a t never need lubrication support the m o t o r shaft. An extra sealed bearing steadies the tube holding the shaft, f o r t r u e running with m i n i m u m deflection. Bronze tank c l a m p and ball-joint mounting permit locking the mixer at any angle. Order it f r o m your supply house, or write us. Specify LIGHTNIN Model XP Mixer: With motor lead wires but w i t h o u t cord, for H O v 60cy I p h $ 1 3 0 . 0 0 There's a full line of heavy-duty LIGHTNIN Mixers and accessories for the laboratory. Bulletin B112 describes t h e m all. To receive it, check reader service card or write us.
Lightin
Mixers
MIXING EQUIPMENT Co., Inc. 160-e Mt. Read Blvd., Rochester 3, N . Y . In Canada: Greey Mixing Equipment, Ltd., TOO Miranda Ave., Toronto 19, Onf. in Europe: Lightnin Mixers, Ltd., Poynton, Cheshire, England Circle No. 5 on Readers' Service Card
