472 PRACTICAL ORGANIC CHEMISTRY nated rubber pressure tubing over a glass-to-glass joint. The side-arm 1 (Fig. 86) of the carbon dioxide absorption tube is attached by a similar joint to a small guard-tube V containing perchlorate to prevent any water vapour reach-ing the perchlorate in the absorption tube. This end of the absorption train is supported by a small wire hook attached to a stand. The Mariotte bottle. The perchlorate guard tube is attached by a length of ordinary rubber condenser tubing to the Mariotte bottle W. This is, in effect, a siphon bottle, and the lead-in tube X is a capillary provided with a tap T 1 . The bent capillary Y (drawn off slightly at the end) serves as exit tube; it is fitted into W by a rubber bung and its level may be adjusted. By the time the oxygen stream has reached the absorption tubes its initial excess pressure (ca. 6 cm. of water) has been almost completely dissipated by the resistance afforded to its passage by the packing of the combustion tube. The
This is the end of the preview. Sign up
access the rest of the document.