File:A text-book on chemistry. For the use of schools and colleges (1866) (14796440953).jpg

Identifier: textbookonchemi00drap (find matches)
Title: A text-book on chemistry. For the use of schools and colleges
Year: 1866 (1860s)
Authors: Draper, Henry, 1837-1882
Subjects: Chemistry Physics
Publisher: New York, Harper & brothers
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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utiful symmetry, as seen in Fig. 206(page 236). Similar flower-like shapes may be seen onmelting the interior of a block of ice by the aid of abeam of sunlight or the electric lamp. The compressibility of water is demonstrated andmeasured by an instrument invented by Oersted, inwhich pressure can be exerted upon water in a tube bymeans of a screw. It shows that water is com- Fig.m.pressed -^-.^o-o Part °f *ts volume for each atmos-phere of pressure. The constitution of water was first proved byCavendish and Watt in 1781. It can be illustratedin a variety of ways. Thus, if over a jet of burn-ing hydrogen a cold glass bell be suspended, Fig.207, it becomes soon covered with a misty dew,andif the experiment be prolonged, drops ofliquid finally trickle down the sides, and may be What is the specific gravity of water and steam ? What does Fig.206 represent? What is the amount of compressibility of water?How may the composition of water be synthetically shown ? 236 SNOW CRYSTALS. Fig. 206.
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caught in a vessel placed to receive them. This liquidis water, which has arisen from the union of hydrogenwith the oxygen of the air. It may be slightly acid, SYNTHESIS OF WATER. 237 from the presence of nitric acid produced by oxidationof the nitrogen of the air. If in a vessel over the mercurial trough twenty meas-ures of hydrogen are added to ten measures of oxygen,and a small pellet of spongy platinum passed up throughthe quicksilver, union between the two gases rapidlytakes place, so that it is usual, in order to moderate i^saction, to mix the spongy platinum previously with alittle pipe-clay. As the gases unite the mercury rises,until at last they totally disappear. This experimentshows that the constitution of water by volume is 2 ofhydrogen to 1 of oxygen. The composition of water by weight was determinedby Berzelius as follows: Let a flask, a, Fig. 208, con- Fig. 208.

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