Using a refractometer...ummm...how?

[raffike]

Raf discovered he has a brand new refractometer(or he thinks it is refractometer).It something like microscope but lot more buttons to turn and stuff.There are two mirrors attached to it and a tube i can look inside.When i turn a button i can see numbers running from 1.3 to 1.7 like 1.301 1.302 1.303 etc.I can also split one moving part that looks like a lens or something.Raf has never seen anything like that.Are refs easy to use?When i look inside of the tube,besides numbers there is another screen or somethign that goes darker/brighter as numbers change.I saw less than dozen thread on TFSE on refractometers,they don't seem to be popular over here...

[hypo]

general points:

first of all it's very important to have it temperated. for that you need
a thermostat, which you connect to the refractometer. (it surely has
two connections for that). refraction indices are highly temperature
dependant and are usually given for 20°C.

always keep the glass clean (eg with alcohol), take care not to
scratch it!

how to use:

* open the thing (the moving part you talk about), place a drop of your
substance on it and close it.
* look through the "tube". now turn the big knob and somewhere you should
see a sharp border between a bright and a dark region. adjust this
border to be exactly at the center.
* read the number. this is your refraction index.
* be amazed at how impure your product is    
* open the thing and clean it with a tissue and some alcohol (bottom and top).
close it. done.

[raffike]

Does the light from the lamp have to fall on lens(which is splitable) under certain angle or is it not important

[hypo]

is the lamp attached to the refractometer?

if yes, then just bring it as close as possible to the lens,
after you have introduced your sample and closed it again.

[raffike]

No,there is no lamp but there is a mirror that you can use to reflect light to sample,actually there are 2 mirrors,other one is to illuminate number screen.I think i'll inspect this ref little more carefully...

[raffike]

Hmmm...wierd stuff that is.There are three windows on that moving part,that splits into 2,where you put that sample in,one in the cover and 2 in the in the lower part,one is closable with some cover.When lamp was pointed to one window i could see some light that went brighter as i turned the knob,other window was acting basibally same way,no sharp line between dark and bright,even when a sample of safrole was put onto dull sample screen on upper part of that splitable moving part.

[hypo]

could you please post a picture, in order to be sure
that we're talking about the same thing?

it's some time since i saw one of those, but iirc, the light
should enter through the opening with the flap. you need a
bright lamp, but afaik it needn't be polarised or monochromatic
or shit like that. just put the lamp as close as possible to
the opening.

concerning the sample: i don't know if i was clear enough,
but the sample is put on horizontal part, which is not on
the moving thing. using an eyedropper, you can smear the
drop a little bit, to get better spreading. after closing
the apparatus, there should be a knob, with which you can
fixate it (so that it is tightly closed). use it.

once it is closed, there is only one opening (the one with the
flap), isn't it?