MICROCIRCUIT JIG AND MASK CHANGER The micro-circuit jig is complete with a sixposition vapor source, enabling six 2" square substrates to be coated with six different materials using six different masks. The jig is also provided with two substrate heaters, one to preheat the substrate to 150" C. and the second to raise the temperature of the sub strate in the evaporation position to 300° C. Resistance monitor pick-up points are pro vided and separate resistance monitor and automatic source shutter can be provided. Standard EDWARDS patented glow dischargecleaning rings are supplied with the jig, along with the rotating six-position vapor source. The accuracy of registration of each successive mask in contact with a given sub strate is within ±0.001".
SPEEDIVAC
MULTIPLE VAPOR SOURCE VACUUM COATING UNITS EDWARDS HIGH VACUUM has pioneered the design and development of evaporation systems and accessory equipment from small versatile laboratory units to high capacity production plants. All "Speedivac" evapora tors are supplied ready for production, and, of course, fast reliable pump downs are standard on all EDWARDS equipment .
EDWARDS
HIGH
VACUUM,
INC. 3 2 7 9 GRAND ISLAND BLVD., GRAND ISLAND, Ν . Υ . Circle No. 59 on Readers' Service Card
NESTER SPINNING BAND DISTILLATION COLUMNS An improved type for use under high vacuum . . . developed to meet the need for a labora tory still superior to conventional types in the fractionation of heat-sensitive or high-boiling, high viscosity liquids. The columns contain spiral screen bands having 300 teeth per inch contacting the walls of the still. This construction provides violent agita tion of the reflux liquid and gives intimate contact of descending and ascending vapors. The reflux ratio of the still is controlled by means of an adjustable needle valve eliminat ing the possibility of leakage. • high fractionating
efficiency
·
designed
to operate
pressures down to 7 0 - 6 mm H g · free from leaks, tion of stopcock lubricants,
mechanical difficulties
low tendency to flood · available
at low
contamina ·
extremely
in a variety of sizes of mini
mum cost.
for purchase or more information, call or write
nester
faust
2401 OGLETOWN RD. NEWARK, DELAWARE
Circle No. 14 on Readers' Service Card 36 A
•
ANALYTICAL CHEMISTRY
REPORT
rise in the chamber and a steady output of useful energy. Under knocking conditions, the flame be haves similarly at first. Then com bustion occurs suddenly throughout the rest of the mixture, producing a detonation. Other pre-flame and post-flame reactions also were dis covered. Recent analytical work on the quenching effect of the relatively cold walls of the combustion cham ber has brought to light information bearing on the smog problem. Instrumentation and Chemical Analysis Analytical chemistry is by nature a mixture of chemistry and physics. Samples are transformed by chemi cal processes into forms suitable for the measurement of some physical property. T h e rise of instrumental analysis and a new emphasis on re search, particularly structural stud ies, is the common trend of analyti cal practice. There is no denying the movement toward less chemi cal manipulation and more direct physical measurement on the origi nal, unaltered material. B u t a primary result has been to free the analyst from repetitive manipulations t h a t hold little challenge to his ingenuity once the technique has been devised. T h e analyst's growing familiarization with the physics and electronics re lated to his instruments has brought about new angles of a t t a c k on old analytical problems. Instrumental analysis has made possible a new level of sensitivity and permits re search in the effects of residual and trace elements which previously was not possible. W e t chemical analysis has not de creased in importance. Most ana lytical instruments are compara tive in nature, providing a rapid means of evaluating an unknown in terms of a reference material. T h e establishment of references still de pends on wet chemical determina tions. Finally, the unorthodox problem which won't fit standardized, in strumented procedures is still in ex istence. I t will continue to provide a challenge to the analyst who is skilled with balance, crucible, and buret. END •
