Practical Chemistry; A Course of Laboratory Work
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1887 edition. Excerpt: ... for the molecular weights of these compounds. As will be seen from the annexed figure (Fig. 43) the apparatus consists essentially of a large cylindrical bulb b of about 80 c.c. capacity, fused on to the lower end of a glass tube about 500 mm. long, which has fused to its upper end an enlarged mouth-piece, provided with a well-fitting cork d. Just beneath the enlargement, a capillary side-tube c is given off. At the bottom of the bulb b is a small cushion of dry glass wool, or asbestos. The apparatus must be thoroughly dried before use, by blowing air into it with a bellows while it is gently heated. (1) To determine the vapour density of ether. Water is caused to boil briskly in the cylindrical glass bath A, and the dried apparatus, with its mouth corked, is so clamped that the bulb b is well surrounded by the steam in A, while the capillary c dips into a small pneumatic trough. The air in b expands and escapes through c; after a time equilibrium is attained, and no more air escapes. When this is the case, the graduated cylinder e is brought over the bee-hive; the cork d is removed, the little flask f containing the ether is dropped into the apparatus, and the cork d is instantly replaced. The dry flask f has been weighed, and then again weighed when completely filled with ether; the flask should contain about-05 gram of ether. The difference in the two weighings (w grms.) gives the weight of ether used. The ether is quickly and completely vaporised in b, and the vapour displaces a corresponding volume of air through c; this air is collected in the graduated tube e. When the vaporisation is complete, as indicated by the cessation of air bubbles from c, the tube e is removed by means of a spoon to a vessel containing water, in which it is...
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- 04 Jul 2012
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