Scientific amusements . produced by the can prepare iron in such atoms that it ignites at anordinary temperature by simple contact with the^air. Tobring it to this state of extreme tenuity, we reduce itsoxalate by hydrogen. We prepare an apparatus forhydrogen as shown above, and the gas produced at Ais passed through a desiccative tube, B, and finally reachesa glass receptacle, c, in which some oxalate of iron is latter salt, under the combined influence of hydrogenand heat, is reduced to metallic iron, which assumes the 24 CHEMISTRY. appearance of a fine black powder. W
Scientific amusements . produced by the can prepare iron in such atoms that it ignites at anordinary temperature by simple contact with the^air. Tobring it to this state of extreme tenuity, we reduce itsoxalate by hydrogen. We prepare an apparatus forhydrogen as shown above, and the gas produced at Ais passed through a desiccative tube, B, and finally reachesa glass receptacle, c, in which some oxalate of iron is latter salt, under the combined influence of hydrogenand heat, is reduced to metallic iron, which assumes the 24 CHEMISTRY. appearance of a fine black powder. When the experimentis completed the glass vessel is closed, and the iron, thusprotected from contact with the air, can be preserved in-definitely ; but if it is exposed to the air by breaking offthe end of the receptacle (see below), it ignites immediately,producing a shower of fire of very beautiful effect. Ironthus prepared is known under the name oi pyrophoric is acted upon in a very powerful manner by most. Pyrophoric iron. acids. If some nitric acid is poured on iron nails, a streamof red, nitrous vapour is let loose, and the oxidised iron isdissolved in the liquid to the condition of nitrate of experiment is very easy to perform, and it gives anidea of the energy of certain chemical actions. We haveendeavoured to represent its appearance on page nitric acid does not act on iron, and prevents itbeing attacked by Ot-dinary nitHb acid. This property has NITRIC ACID. 25 given rise to a very remarkable experiment on passiveiron. It consists in placing some nails in a glass, intowhich some fuming nitric acid is poured, which producesno result ; the fuming acid is then taken out, and is re-placed by ordinary nitric acid, which no longer acts on
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