Elements of agricultural chemistry and geology / [Jas. F.W. Johnston].

  • James Finlay Weir Johnston
Date:
1844
Catalogue details

Licence: Public Domain Mark

Credit: Elements of agricultural chemistry and geology / [Jas. F.W. Johnston]. Source: Wellcome Collection.

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    the foi-mer, though less pure. Black lead is a third va- riety, still heavier and more impure. The diamond is the only fom in which carbon occurs in nature in a state of perfect purity. This latter fact, that the diamond is pure carbon— that it is essentially the same substance with the finest and purest lamp-black—is very remarkable ; but it is only one of the numerous striking circumstances that every now and then present themselves before the inquiring chemist. Charcoal, the diamond, lamp-black, and all the other fonns of carbon, burn away more or less slowly when heated in the air, and are converted into a kind of gas known by the name of carbonic acid. The impure varie- ties leave behind them a greater or less proportion of ash. 2. Hydrogen.—If oil of vitriol (sulphuric acid) be mixed with twice its bulk of water, and be then poured upon iron filings, the mixture will speedily begin to boil surface of the liquid in great abun- dance. These are bubbles of hydro- gen gas. If the experiment be perfonned in a bottle, the hydrogen which is produ- ced will gradually drive out the at- mospheric air it contained, and will it- self take its place. If a bit of wax taper be tied to the end of a wire, and when lighted be introduced into the bottle, (fig. 1), it will be instantly ex- tinguished ; while the hydrogen will take fire, and burn at the mouth of the bottle with a pale yellow flame. If the taper be Inserted before the common air is all ex- pelled, the mixture of hydrogen and common air will bum with an explosion more or less violent, and may even shatter the bottle and produce serious accidents.
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