The Romance of Modern Chemistry

HOW MAN COMPETES WITH NATURE stances gave a severe blow to these old ideas; in fact, it upset them altogether. “ Vital force ” was evidently not necessary for the production of organic substances—a conclusion which has been abundantly confirmed since Wohler’s time, and is being daily confirmed in every chemical laboratory. Suppose, now, we try to fill in the details of this epoch- making discovery, and to see how by mere laboratory operations it is possible to build up or synthesise carba- mide from its elements. The inorganic substance which is most nearly related to carbamide is a compound of carbon, hydrogen, oxygen, and nitrogen called ammonium cyanate, and Wohler discovered that by merely evaporat- ing to dryness a solution of this compound in water a large proportion of it was changed straight away into carbamide. If, then, we show that ammonium cyanate can be made from its constituent elements in the labora- tory, we are justified in saying that carbamide can be produced artificially. The first link in the chain between the separate elements, carbon, hydrogen, oxygen, and nitrogen at the one end, and ammonium cyanate at the other, is acetylene. We have already seen that this gas can be produced from inorganic materials; by heating lime and carbon in the electric furnace calcium carbide is produced, and to get acetylene from calcium carbide only water is required. But a more direct synthesis of acetylene is possible by making an electric arc between carbon rods in an atmos- phere of hydrogen; under these conditions acetylene, which is a compound of carbon and hydrogen, is produced in small quantity. Now acetylene gas, when mixed with nitrogen gas and exposed to the action of electric sparks, combines with 251