Search

The pressure coefficients of resistance of several black-loaded compounds of natural and synthetic polymers were measured at temperatures from 0° to 80° C. The effect is shown to be due to variations of the contact resistance between adjacent black particles.

In the following, an account of the research and development for a new technique of pressure measurement in fluid flow is given. Performances of various pressure transducers using conductive rubber as the sensing element have been investigated. Transducers believed to be the smallest of their kind have been manufactured, with sensitivity high enough to record ordinary speech level pressure variations (about 60 dB) in the af range.

This new miniature pressure transducer depends on the change of resistance across an element of conductive rubber. It responds satisfactorily to pressure fluctuations of 5 × 10-5 atm in the frequency range 20-6000 c/s.

To the Editor:— During transurethral surgery performed under thiopental (Pentothal) sodium-nitrous oxide-curare anesthesia, the anesthesiologist noticed a sparking sound accompanying each electrical manipulation, the smell of burning rubber, and the appearance of smoke. A few moments later, sparks were seen to pass from the operating table to one of the breathing tubes, where it lay across the painted metal edge of the table; the rubber breathing tube was later found to have been burned but not perforated. The anesthesia machine was immediately pushed away from the operating table and the anesthesia system converted from thiopental-nitrous oxide to thiopental-air. It was quickly found that the wire grounding the operating table was not making proper metallic contact with the ground pipe. The electric charge on the table therefore mounted, and finding intermittent contact with the conductive rubber breathing tube, the anesthesia machine and the tube became converted into a sort of ground