4 o PRACTICAL ORGANIC CHEMISTRY is then placed in this annular space to act as a seal whilst the stirrer is in operation. Assembling Apparatus. The following points should be noted. (1) Drying Apparatus. Simple pieces of apparatus such as flasks are best dried by heating in the large luminous flame of a blowpipe, a current of air, e.g., from compressed air mains, being blown through the flask meanwhile to remove the water vapour, which would otherwise merely recondense as the flask cooled. Apparatus such as condensers, etc ., which cannot be so treated, should first be rinsed out with methylated spirit, and then with ether (preferably dried beforehand over calcium chloride and filtered): a brisk current of air is then blown through the apparatus until the ether has completely evaporated. In most laboratories, drying ovens maintained at about 50° are available for the final drying of glass apparatus of all kinds. (2)
This is the end of the preview. Sign up
access the rest of the document.