tation of infrared spectra has proved t o be a success.) I t is hoped t h a t we will continue to see rapid progress and successes in t h e ACS educational programs, particularly in light of substantial coverage t h a t has been given t o instrumental methods of analysis.
BETHLEHEM IHSTRUMEHT MERCURY BEST IN PURITY To qualify as Instrument Mercury, the total residue after complete evaporation of a 200 gram sample may not exceed one part im purity per ten million. All BETHLEHEM Instrument Mercury fully meets this rigid standard—and proves it with the analysis certification included in each shipment.
CONTINUOUS VACUUM, TRIPLE DISTILLATION
Holography A few months ago we mentioned in this column t h a t acoustical holog r a p h y is a field of research t h a t merits t h e attention of analytical scientists because of possible appli cations in the realm of nondestruc tive testing and electronic detection
ALL BETHLEHEM INSTRUMENT MER CURY IS PURIFIED IN THESE STILLS which operate in three continuous stages under vacuum and controlled low tempera ture. '
BEST IN PACKAGING BETHLEHEM Instrument Mercury is avail able in five different polyethylene bottles, with plain cap on the 16-lb. and 65-lb. bottles, and the unique dispensing tip on the 9-02., 1-lb., and 6-Ib. sizes. (Eive and 10-lb. glass bottles are also available.)
[see A N A L . C H E M . , 4 1 , 77A, ( J a n
uary 1969)]. T h e general subject of holography continues t o fasci n a t e u s , and we are now able t o recommend an excellent article, "Holography and its Applications," by Dennis Gabor and George W . Stokes [Nature, 2 8 , 40 ( J a n u a r y 1 9 6 9 ) ] . T h e basic mathematical theory t h a t underlies holography is discussed, along with volume holo grams, holographic interferometry, and holographic image de-blurring. Development of t h e laser as an extremely dependable coherent light source has brought this branch of interferometry into new focus, particularly as regards color photography, three-dimensional mi croscopy, and motion picture pro jection, and for problems in infor mation storage. Although m a n y of the aims of current researchers have not y e t been realized (such as the three-dimensional projection screen), t h e work is so promising t h a t holography must be considered a vital new frontier in optical r e search. As always, t h e Editors are a d vancing t h e idea t h a t major devel opments in physics filter down t o applications in difficult analytical problems a t a deplorably slow rate. Holography is a developing tool t h a t should be close t o the interests of m a n y analytical scientists—and we urge consideration by each of the readers of t h e relevance of holographic research t o his j o b in general and his optical design needs in particular. John K. Crum
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micromeritics ORR SURFACE-AREA PORE-VOLUME ANALYZER measures surfaces areas precisely from 0.001 m V g m u p . . . uses any non-corrosive g a s as a d s o r b a t e . . . no calibration!
MODEL 2100 also for pore size & volume a n a l y s i s . . . chemisorption studies proven 3rd generation design / most versatile, accurate instrument available / all-metal system utilizing classical low temperature gas adsorption B.E.T. tech nique / direct pressure read-out from 0.0001 mm to 1000 mm Hg / constant volume manifold / temperatures precise ly controlled and measured for accurate data/ range from 0.001 mVgm, no known upper limit / accuracy and reproducibili ty 0.5% / size 22" W by 23" D by 68" H. Write for complete descriptive literature, technical information and details on obtaining sample analysis of your material. INSTRUMENTS
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