± 1/20, ± 1/100, ± 1/200 of a pH. If the first isn't accurate enough, pick one of the other two. W e ' v e designed a w h o l e new family of p H meters—the A2 Series. They give y o u a c h o i c e of relative accuracies: ± 0.05, = t 0.01 and ± 0.005 p H . But t h a t ' s n o t a l l by a l o n g s h o t . We've modernized and perfected the meters in every significant detail. For i n s t a n c e , w e ' v e c h a n g e d t o photoconductive choppers which are inherently more stable and trouble-free. They avoid the self-generated stray signals of mechanical converters. We've adopted the glass-electrode c o n n e c t i o n s n o w p o p u l a r in U. S. practice. We've given the meters a new look. Increased their stability, reliability, reproducibility.
But we still rely on our feedbackstabilized amplifier whose basic concept has been so widely imitated. A n d hand wiring. A n d a highly responsive meter w i t h the practical scale length of 7". (Not for us t h e u n s t a b l e z e r o o f o v e r s i z e d meters!) A n d taut-band suspension. Eliminating the dead band you get w i t h pivot systems. And a rugged housing. Epoxy-coated case. Melamine-coated front panel. And our o w n pH electrodes manufactured to perfectionist standards. All the new meters are line-operated. All have a 10 microamp polarizing curr e n t f o r m e a s u r e m e n t s by t h e Karl Circle No. 117 on Readers' Service Card
Fischer method and o u t p u t terminals for recorder display. Choose the one you need. General Purpose — g o o d for routine measurements in lab and plant. Expanded Scale —for the more exacting requirements of research or quality control. Precision — f o r h i g h e s t p r a c t i c a l a c c u r a c y in r e search, medicine or industry. You'll get a great deal that's n e w . . . at the same o l d price. For details on each and for the name of the L&N laboratory pH dealer nearest you, write t o : Leeds & Northrup, 4906 Stenton Ave., Philadelphia, Pa. 19144.
LEEDS Philadelphia 44
&
NORTHRUP
Pioneers in Precision
