One must not confuse the tyndall with the absorption curve for CS. They tyndall drops off rapidly with decreasing particle size, and with increasing wavelength. Thus a blue beam will show a great deal more tyndall than a red beam (that is why the sky and skim milk appear blue). But I think the ratio between the intensities of the different colors will remain essentially the same, independent of particle size. I will have to pull out my old papers and find the actual equations to be sure.
On the other hand, the aborption curve for particles is rather sharp for any one size, and starts at uv for very small particles, and the wavelength decreases with increasing particle size moving into blue (looks yellow), green (looks orange), yellow (looks red), orange (looks green), red (looks blue) and infrared (back to colorless again). So the tyndall is a totally different effect than the apparent color. Marshall blue_eyes wrote: > Hi "Ole Bob", > > Yes, I understand the need for a nice coherent beam if a > person is going to eyeball it for the Tyndall effect. > > I was thinking more along the lines of having red,green and blue > LEDs on one side of the cell and light sensors on the other side to > measure the light transmission changes for each wavelength. > > Based on some of the thoughts expressed on this list,it seems > we would expect to see changes in blue first,then green and > finally,red. Perhaps one might wish to stop brewing when a > certain reading in green or red is reached. > > This might give a qualitative spin on the conductivity readings. > Plotting conductivity versus Tyndall readings for a brewing run > might show something interesting. > > I have been keeping samples of each batch to check conductivity > and Tyndall effect over time as I seek to stabilize my process > and if this idea is workable, I could also check to see if there > are shifts in wavelength readings over time. If there is a shift > to higher readings in the green and red wavelengths,and the blue > readings go down, this might tell us something about the changes > in particle size as related to storage containers,light exposure, > etc. > > Just thinking out loud, does anyone else have an interest in this > sort of thing? > > David > ----------- > > "Robert L. Berger" wrote: > > > > Hi Blue eyes; > > > > One needs laser diodes for this purpose and they come in 635 to 685 > > nanometers which is in the IR zone. NEC manufacture on page > > 54 of Mouser cat. > > > > I t might be possilbe to rig up a set of optics to focus the beam from a > > standard diode but it wont be simple. > > > > So the hunt is still one for other color laser diodes. > > > > "Ole Bob" > > > > > s > > > > -- > > 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]> > > -- > E-mail: [email protected] > Fax to: 1-253-681-1133 > ICQ#... 44960928 > > _____NetZero Free Internet Access and Email______ > http://www.netzero.net/download/index.html
