24 A
ANALYTICAL
CHEMISTRY
INSTRUMENTATION the multivibrator t o drive t h e solenoids directly, thus eliminating the use of a relay.
MACHLETT Auto-Burettes and Pipettes
are
fite^eMed/
• COMPLETELY
AUTOMATIC
Self-setting at the zero point.
• EASY TO OPERATE O n e stopcock controls all action.
• GRAVITY FILLED N o error due to air bubbles, even with viscous substances.
• OPERATES ON ONE A I R VENT Single opening guarded by soda lime tube gives maximum protection against contamina tion.
• SIMPLIFIED
CONSTRUCTION
Easy to clean.
• NO WASTE Overflow solution returns to reservoir.
• COSTLY BREAKAGE REDUCED Heavy iron stability.
T
tripod
stand
gives
ample
LSU
Symposium
Analysts have come t o regard t h e annual Louisiana State University Symposia on Modern Methods of Analytical Chemistry as an indis pensable event on their professional calendar. T h e fifth meeting, J a n u ary 28 t o 31 was no exception t o the rule. Within t h e diversified program [Chem. and Eng. News, 29, N o . 50, 5276 (1951)] several outstanding contributions were of interest t o t h e instrument-minded analyst. Olen Nance gave an ex cellent resume of t h e status of high frequency methods. T h e theory of resonant circuit behavior a t mega cycle frequencies is complex enough, b u t t h e analyst must go beyond this in order t o interpret t h e behavior of substances in such fields in terms of their physicochemical properties. Fortunately, much of this interest ing work is currently appearing in
H E S E TWO EXCLUSIVE products of E . M a c h l e t t & Son a r e of i n s t a n t
t h e pages of ANALYTICAL C H E M I S
appeal because of their extreme simplicity of construction a n d opera tion. B y simply turning one precision ground stopcock, a specified volume of fluid can be dispensed quickly, accurately a n d conveniently. There are no rubber bulbs t o press n o r a n y complex valves t o adjust. Order today a n d you'll find—as many other scientific labs have found — t h a t t h e M a c h l e t t Auto-Burette a n d Pipette are u n m a t c h e d in perform
TRY and m a n y of its useful applica tions will be better understood as a consequence.
ance. #8-526 Auto-Burette made of "Pyrex" brand chemical glass to Bureau of Stand ards specifications. Complete as illus trated. Reservoif Cap., ml.
500 1000 1000 1000 2000 2000
Burette Cap., ml.
2 5 5 10 25 50
Subdivisions
Price
$22.50 23.75 23.00 25.00 27.00 28.50
0.01 0.02 0.05 0.05 0.01 0.01
#71-645 Automatic Pipette made of "Pyrex" brand chemi cal glass. Complete as illus trated. Reservoir Cap., mi.
Pipette Cap., ml.
1000 1000 2000 2000
5 10 25 50
Price
$20.50 21.50 23.00 24.00
Both Burettes and Pipettes are available in amberiied slass at a slight Increase in price.
For further
For the
information
finest
write for Bulletin
in specialized
glass
"A-B"
apparatus
A heritage of over 50 years of skill and experience lies behind every piece of glassware from our modern glass blowing department. Thus, we are able t o offer you t h e finest in scientific and technical apparatus—precisely made to your specifications and draw ings. Let us furnish an estimate on your particular needs.
E.MACHLETT&SON ESTABLISHED 1897
Laboratory 220
APPARATUS · SUPPLIES - CHEMICALS
E A S T 2 3 rd
STREET
N E W Y O R K . 10. Ν.Υ.
W. D . Cooke and Donald DeFord provided additional glimpses of t h e exciting possibilities in t h e field of coulometric titrations. T h e a p proaches of these two investigators is complementary; t h e former h a s been concerned with internal gen eration of reagents and with super sensitive means of end-point d e tection. This has yielded analyses for submicrogram quantities, which for precision and sensitivity rival the spectrographic method. T h e latter is extending t h e general field of external generation of reagents by coulometric methods with means for completely automatic operation. There are now several accurate pro cedures which involve nothing more t h a n a precise measurement of cur rent and elapsed time. Philip W. West h a s once more served t h e analyst handsomely in arranging these symposia.
