File:Practical methods of organic chemistry (1901) (14585163687).jpg

Identifier: practicalmethods00gatt (find matches)
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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absorption apparatus there must be a sufficient amount of mercuryto extend almost to the side-tube; if this is not the case, more mer-cury is added: the end of the glass tube passing through therubber stopper must be flush with the end of the stopper. Inorder to protect the latter from the heat, there is placed over theportion of the tube projecting beyond the furnace, an asbestosplate having a circular opening in the centre. After opening thepinch-cock of the absorption apparatus, the burners under the lasthalf of the magnesite are lighted; the flames, being small at first,are increased in size, as soon as the tube becomes warmed, but notsufficiently to cause them to meet above the tube. In order toraise the temperature higher when it becomes necessary, the tubeis covered from both sides with the tiles. After about ten minutesa rapid current of carbon dioxide is evolved, the magnesite beingdecomposed by heat as represented in the following equation :MgC03 = MgO + CQ2. 90 GENERAL PART
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ORGANIC ANALYTICAL METHODS 91 During this operation the glass stop-cock of the absorption appa-ratus is opened, and the pear-shaped vessel placed as low as pos-sible, so that it contains the principal portion of the caustic potash.After a rapid current of carbon dioxide has been evolved for aboutfifteen minutes, the burners under the copper spiral are lightedin order to drive out any occluded gas (hydrogen), the pear-shaped vessel is raised high enough to cause the caustic potashto ascend somewhat above the tubulure in the glass cock, thelatter is closed, and the pear-shaped vessel again lowered as faras possible. When the air in the tube has been completelyreplaced by carbon dioxide, only a minimum quantity of lightfoam should collect over the potash in the course of two minutes.If this is not the case, and a large air volume collects, the glasscock is opened, upon which the potash flows in to the loweredpear vessel, and carbon dioxide is caused to pass through thetube for five minut

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