Acold finger is a piece oflaboratory equipment that is used to generate a localized cold surface. It is named for its resemblance to afinger and is a type ofcold trap. The device usually consists of a chamber that a coolant fluid (cold tap water, or perhaps something colder) can enter and leave. Another version involves filling the device with a cold material (examples:ice,dry ice or a mixture such as dry ice/acetone or ice/water).^[1]

Typically a cold finger is used in asublimation apparatus,^[2] or can be used as a compact version of acondenser in eitherreflux reaction ordistillation apparatus. Many commercially availablerotary evaporators can be purchased with a cold finger in place of aDimroth condenser, for example. When used as a condenser in a rotary evaporator, cold fingers can be cooled to a lower temperature of −78 °C (dry ice), compared with water condensers that can be cooled to −40 °C (ethylene glycol/water mixture). The lower temperature achieved reduces the quantity of volatile material exhausted into the air.

• 
  A cold finger which includes a vacuum outlet.
• 
  Camphor beingsublimed. The crude product in the bottom is dark brown; the white purified product on the bottom of the cold finger above is hard to see against the light background.
• 
  Dark green crystals ofnickelocene, freshlysublimed on a cold finger.

• Laboratory glassware

• CS1 errors: ISBN date
• Articles with short description
• Short description matches Wikidata