List, Make your own conductivity calibration solution.
To calibrate the meter including probes accurately, a calibrating liquid is required. A saturated calcium sulphate (CaSO4) solution is eminently suitable for this purpose: at 20 deg C, this has a conductance of 1976 uS cm-1 (micro-Siemens per centimetre). The solution is prepared by mixing calcium sulphate in distilled water until the liquid accepts no more of the CaSO4. Note, however that CaSO4 is only slowly soluble in water. By adding an identical volume of water to the solution, the conductance will be halved. Doubling the volume again by adding distilled water will halved the conductance once more. While calibrating the meter, make sure that the solution remains at 20 C, because the conductance varies with temperature. Ref. Elektor 304 circuits. #201 Conductance Meter. 910039 - 12 Tony -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
