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Rh in this his first important research he employs the balance—"the essential instrument of all chemical research." He heated water in a closed and weighed glass vessel for a hundred and one days, and at the termination of the experiment found that the vessel had lost 17·4 grains, and on evaporation of the water a solid residue weighing 20·4 grains was obtained—the excess being due to unavoidable experimental error. Lavoisier concluded that water when heated was not transmuted into earth, which was the theory entertained by the alchemists and some of the pneumatic chemists. He proved that the water dissolved some of the constituents of the glass—a conclusion confirmed by Scheele. This research had a far-reaching and an important bearing on the notions or theories of the times—theories that had existed for centuries were to be swept away by his clinching experimental proof of their absurdity; the art of alchemy and the pursuit of the philosopher's stone was rendered futile; but, above all, the experiments proved that the old alchemical idea of the transmutation to be false; and it led him to