Non-Sparking—Speed Controlled—Long Wearing
the ANALYST'S column
Welch ELECTRIC STIRRER with Sp-al/uesU
L.T. Hallett, Editor
INDUCTION TYPE MOTOR r p i i E use of infrared spectroscopy to identify the chemical compounds in a material of unknown composition has been increasing phenomenally in the last ten years. As the method is based upon t h e fact t h a t each chemical compound can be identified by its distinctive infrared absorption spectra, one of the real problems is how best to sort through the spectra on file to find the one or more which check t h a t of the unknown material. T h e number of spectra available commercially exceeds 15,000 and new ones are being produced at a r a t e of a b o u t 3500 a year. This number added t o those produced in the individual laboratories adds up to a formidable d a t a - h a n d l i n g problem. The American Society for Testing Materials is indexing all available infrared spectra on I B M cards, the number of index cards now available being about 13,000. E v e n with the introduction of this index, however, the sorting problem has not been solved. F o r example, one sort through this deck with an I B M sorter would require 52 minutes at the rate of 250 cards per minute, and for an identification to be made, several sorts are required. AVhile faster sorters are available, m a chine cost increases proportionately. One approach to this problem has been to presort the I B M deck into smaller groups based on some chemical or physical characteristic, such as functional group or melting point. To use such a deck, however, the analyst must have some previous knowledge concerning the composition of the unknown, and the person doing the sorting must h a v e sufficient chemical knowledge to direct the sorts. Procter & Gamble scientists set out to find a completely mechanical
Reduces Explosion Hazard Watt-Type Governor Stabilizes
Speed
Delicately Controlled Variable Range of Speed (200 to 1,400 R.P.M.)
$54.75
Long Life and Dependable Service S230. ELECTRIC STIRRER, Sparkless. Complete with 6-foot connecting cord, line switch, and plug. For operation on 50 or 60 cycles, 115 volts A.C. Each S54.75
No. 5230
5230A. ELECTRIC STIRRER, Sparkless, for 230 Volts, A.C. Consists of No. 2530 Stirrer equipped with a step-down transformer to permit operation on 230 volts, 50 or 60 cycles A.C. Each Î64.50
W. M. WELCH SCIENTIFIC COMPANY DIVISION CFW, M. WELCH MANUFACTURING COMPANY
-ESTABLISHED 1 8 8 Ο Ι 515 SEDGWICK STREET, DEPT. A - 1 , C H I C A G O 10, ILLINOIS, U.S.A. Manufacturers of Scientific Instruments and Laboratory Apparatus
HEVI DUTY
"Multiple Unit"
HOT PLATES! are built for
CONTINUOUS OPERATION WIDELY USED IN LABORATORIES FOR: •
HEATING AND EVAPORATING SOLUTIONS
•
ALCOHOL AND ETHER EXTRACTIONS
•
DRYING OF PRECIPITATES
•
DISTILLING, BOILING, ETC.
HEVI
DUTY
LABORATORY FURNACES
Hevi Duty Hot Plates are con structed to give you dependable trouble free service. The metal top plate is resistant to warpage. Coiled wire elements are protected in refractory holders so located as to give a uniform heat over the entire top surface. Controlled temperatures up to 750° F. Seven standard sizes are available from stock, special sizes and temperatures by order. Write for Bulletin LAB-835.
ELECTRIC MULTIPLE
UNIT
COMPANY ELECTRIC EXCLUSIVELY
MILWAUKEE 1, WISCONSIN For further information, circle number 55 A on Readers' Service Card, page 83 A VOL. 30, NO. 4, APRIL 1958
·
55A
