3 good ways to solve your pH problems A reliable laboratory worker . . . The Coleman Model 18A Stable, accurate, easy to handle. Stable because it is fully protected from moisture and corrosion and against AC line voltage changes. Accurate because the exclusive Coleman Guard Circuit prevents stray currents and insures precise electrode function. Convenient . . . electrodes are at the front of the instrument and lower into a protecting well when not in use. Electrode arrangement is particularly handy for titrations or use with small samples. Double scale . . . calibrated 0 to 14 pH in steps of 0.1 pH and in millivolts from 0 to 1400 in 10 mv. steps. AC line operated. Priced at $215.00 Precise pH measurements anywhere . . . with the Compax. In the plant or in the field, this 6 pound instrument will give you laboratory accuracy. Completely self-sufficient— carries its own power supply, buffers, everything in one small case. Operates entirely with one knob. Uses a flashing signal instead of a meter to indicate balance, pH is read directly from a calibrated dial. Electrode chain rises into place automatically as the case is opened. This is a real pH meter, accurate to less than 0.05 pH and priced at only $177.50.
t.w Fully Automatic Titration . . . the Coleman Autotrator Addition of titrant to test solutions is automatically controlled and then stopped when the end point is reached. Designed for use with the Model 18A, this time-saving tool is within the reach of any laboratory. By using the direct pH indicating Model 18A, settings are so quickly made that even a single titration can be made profitably. The exclusive "Watchful — Wait" circuit makes the Autotrator pause while the solution stabilizes near the end point. The Coleman Model 19 Autotrator costs only $310.00. Write for full details If you don't already have a copy of Coleman's "Tools for Science," ask for this 60 page book. It contains a short discussion of the vital points in pH measurement as well as a full description of these fine instruments. Dept. A.
Coleman Instruments, Inc. M a y w o o d , Illinois
Coleman pH Meters For further information, circle numbers 9A-1, 9 A-2 on Readers' Service Card, page 47 A
V O L U M E 2 7, N O . 4, A P R I L
1955
9A
