The Finest Oils, Greases, Waxes...
REPORT
f o r High Vacuum Work—also Lubricant f o r High Vacuum Equipment, Masking of Circuit Boards and Other Scientific
Applications
Vacuum pressures of these excellent oils are as low as 1 0 7 torr. Greases as low as 111·11 torr at room tem perature. Scientists, who try Apiezon oils, prefer them for equipment usea in nuclear physics, cyclotrons, elec trical equipment, vacuum tubes, etc.; the greases for general laboratory work and gas-liquid chromatogra phy; wax W with suitable solvent as a masking media. As exclusive distributor in the United States, we offer immediate shipment from stock on the complete range of Apiezon products. For applications, working characteristics, and list prices, write for new Bulletin 43-AC.
J A M E S G. B I D D L E
BIDDLE
CO.
614
Electrical and Speed Measuring Instruments
PLYMOUTH MEETING, PENNSYLVANIA 19462 Phone 215/646-9200 Circle No. 41 on Readers' Service Card
Figure 4. Reflection Topograph of Gallium Arsenide, (a) (242) Plane Diffracting (b) (440) Plane Diffracting
10 DAYS FREE! ff
T&UflkTWi
Clip this coupon, send it and you'll have the opportunity t o try a fantastic miniature w e l d i n g instrument, the Little Torch, for 10 DAYS FREE. Try the L i t t l e Torch in the lab or at home. Precision bond any size metal part f r o m a tiny .002" w i r e to 16 gauge steel. Modify test equipment. Construct m i n i a t u r e prototypes. Solve f a b r i cation problems f r o m welding minute high temperature metal pieces, to heat-bonding Kovar to glass. T r y the Little Torch for 10 days. If you can't see a hundred different uses for this amazing tool, send it back without obligation. Fill out your coupon now. Send it t o d a y ! If you are not interested in a free t r i a l , but wish more i n f o r m a t i o n , w r i t e : Tescom Corp., I n s t r u m e n t f
Tescom CORPORATION
Instrument
2 6 3 3 S.Ε. 4 t h St. Mpls., Minn. 5 5 4 1 4
VALUABLE COUPON ι—ι B a s i c K i t I n c l u d e s L i t t l e I—I T o r c h , 5 Tips, Hoses, and Adaptors $60.50 Basic Kit Plus Regulators Includes Torch, Tips. Hoses, an Oxygen Regulator, and an Acety lene Regulator $130.50 C o m p l e t e O u t f i t Includes Torch, Tips, Hoses, Regulators, Filled Acetylene and Oxygen Tanks, plus Handy Carrying Caddy $242.00
•
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S e n d to: Tescom
Corp.,
ΙΟ
DAY
FREE
Dept. 313 6, 2633 S.E. 4th St., Mpls.,
Circle No. 2 on Readers' Service Card 3 6 A
·
ANALYTICAL
TRIAL!
I understand this coupon entitles me to a 10 DAY FREE TRIAL of the Little Torch kit I've indicated. After 10 days I may return the Kit without obligation or you invoice me at price listed here. NAME FIRM ADDRESS CITY STATE . ZIP CODE
CHEMISTRY
Minn.
55414
tion topograph from a gallium arsenide slice t a k e n with the (242) planes diffracting. N o t e the dislo cations. Figure 4 ( 6 ) shows the same slice with the (440) planes diffracting, and it is seen t h a t the dislocation is now much more in tense. I t can be shown t h a t this in tensity is a minimum when the Burger's vector is parallel to the diffracting planes, and a m a x i m u m when it is normal. T h e Burger's vector is simply the direction in which the lattice is displaced and can be deduced from t h e crystal orientations when the intensity of the line is a m i n i m u m and a maxi mum. T h e dislocation axis can be deduced from the plane along which the slice has been taken. If the Burger's vector and the dislocation axis are normal, the dislocation is an edge dislocation ; if they are p a r allel, the dislocation is a screw dis location. If the image intensity has no point of extinction, then this is not a dislocation but a mechani cally induced fault such as a micro crack or scratch, or a precipitate.
