File:Image from page 112 of "Practical methods of organic chemistry" (1901) (14748630216).jpg

Identifier: practicalmethods00gatt Title: Practical methods of organic chemistry Year: 1901 (1900s) Authors: Gattemann, Ludwig. [from old catalog] Subjects: Publisher: [n.p.] Contributing Library: The Library of Congress Digitizing Sponsor: The Library of Congress

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Text Appearing Before Image: e may be absorbed, theend of the delivery tube is dippedunder the surface of the watercontained in a wide-mouth cylin-der, as represented in Fig. 56,care being taken that in thelower bent portion of the de-livery tube no air bubbles arepresent; if there are, they mustbe removed with a capillarypipette. The eudiometer is nowfilled with water, the end closedwith the thumb, inverted anddipped below the surface of thewater, the thumb removed andthe tube clamped to the cylinder, at an oblique angle, so that theend of the delivery tube may be passed under it. The pearsupported by the clamped ring is raised as high as possible abovethe delivery tube, and the glass cock gradually opened. Thenitrogen is thus transferred to the eudiometer, the cock beingleft open until the delivery tube is completely filled with thecaustic potash. The absorption apparatus is then removed, theeudiometer wholly immersed in the water. To obtain the tem-perature, a thermometer, held in the clamp which supported the

Text Appearing After Image: Fig. 56. 94 GENERAL PART delivery tube, is immersed in the water as far as possible. Afterabout ten minutes, the nitrogen has come to the same tempera-ture as the water, the eudiometer is then seized with a clampespecially adapted to this purpose, or crucible tongs, — never withthe hands, — and is raised so far out of the water that the levelof water inside and outside the tube is the same. The volume ofgas thus read off, is under the same pressure as that indicated bya barometer. Calculations of the Analysis. — If s is the amount of substancein grammes, v the volume of nitrogen read at the temperature t°,and b the height of the barometer in millimetres, w the tensionof the water vapour in millimetres at /°, then the percentage ofnitrogen is p: _ v-{b — w)- 0.1256 ~~ 760-(1 + 0.00367- t)-s The calculation of the analysis is rendered easier by referring tothe table in which the weight of one cubic centimetre of moistnitrogen is given in milligrammes at different temperatures

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