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H-C-C-H
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Carbon atoms belong to the quadrumani like the monkeys, so they are peculiarly fitted to forming chains and rings.  This accounts for the variety and complexity of the carbon compounds.

So when acetylene gas mixed with other gases is passed over a catalyst, such as a heated mass of iron ore or clay (hydrates or silicates of iron or aluminum), it forms all sorts of curious combinations.  In the presence of steam we may get such simple compounds as acetic acid, acetone and the like.  But when three acetylene molecules join to form a ring of six carbon atoms we get compounds of the benzene series such as were described in the chapter on the coal-tar colors.  If ammonia is mixed with acetylene we may get rings with the nitrogen atom in place of one of the carbons, like the pyridins and quinolins, pungent bases such as are found in opium and tobacco.  Or if hydrogen sulfide is mixed with the acetylene we may get thiophenes, which have sulfur in the ring.  So, starting with the simple combination of two atoms of carbon with two of hydrogen, we can get directly by this single process some of the most complicated compounds of the organic world, as well as many others not found in nature.

In the development of the electric furnace America played a pioneer part.  Provost Smith of the University of Pennsylvania, who is the best authority on the history of chemistry in America, claims for Robert Hare, a Philadelphia chemist born in 1781, the honor of constructing the first electrical furnace.  With this crude apparatus and with no greater electromotive force than could be attained from a voltaic pile, he converted charcoal into graphite, volatilized phosphorus from its compounds, isolated metallic calcium and synthesized calcium carbide.  It is to Hare also that we owe the invention in 1801 of the oxy-hydrogen blowpipe, which nowadays is used with acetylene as well as hydrogen.  With this instrument he was able to fuse strontia and volatilize platinum.

But the electrical furnace could not be used on a commercial scale until the dynamo replaced the battery as a source of electricity.  The industrial development of the electrical furnace centered about the search for a cheap method of preparing aluminum.  This is the metallic base of clay and therefore is common enough.  But clay, as we know from its use in making porcelain, is very infusible and difficult to decompose.  Sixty years ago aluminum was priced at $140 a pound, but one would have had difficulty in buying such a large quantity as a pound at any price.  At international expositions a small bar of it might be seen in a case labeled “silver from clay.”  Mechanics were anxious to get the new metal, for it was light and untarnishable, but the metallurgists could not furnish it to them at a low enough price.  In order to extract it from clay a more active metal, sodium, was essential.  But sodium also was rare and expensive.  In those days a professor of chemistry used to keep a little