Talk:Cold finger

Cold finger photo

Can I just ask how the cold finger shown in the photo works (Image:Cold_finger_1.jpg)?

It looks like you have an all in one piece apparatus. I note it has a ground glass joint which to attach to another vessel, however, it seems that the vacuum would only serve to insulate the finger from the 'outside vessel'?

If it is indeed a 'all in one piece apparatus' for use in sublimation I can't see how it will easily work, i.e. how do you get a solid into it, and then back out - I hope not through the stop-cock? Am I being dim? Quantockgoblin 17:26, 31 October 2006 (UTC)

As you correctly noted, there is a size 24 ground glass joint here. You fit the cold finger to another RBF, Schlenk flask or Schlenk tube, immerse in an oil bath or sand bath, and crank up the heat. The vacuum sidearm is for when you are subliming stuff from a plain old RBF which does not have a sidearm of its own. --Rifleman 82 17:39, 31 October 2006 (UTC)

I guess I can't see the hole (obviously not in the cooling system) running from the vacuum tap to where the RBF would be attached. I presume there is one? -- Quantockgoblin 17:53, 31 October 2006 (UTC)

I am being dim after all - the vacuum system does not encase the cold finger at all - the image is a bit blurry, and I think the shadows tricked the eyes into thinking there was another glass wall surrounding the cold finger. -- Quantockgoblin 17:53, 31 October 2006 (UTC)

The joint is concentric about the actual cold finger. The space in between the cold finger and joint leads to the vacuum line. Sorry about the image quality; best I can do with my camera phone. :) Rifleman 82 18:01, 31 October 2006 (UTC)

Does the coolant that runs through the cold finger need to be cooled? Basically how is the coolant below room temperature?(ARJ)