THE CHEMIST AS CREATOR 



MODERN Chemistry practically dates from the time 

 when the burning fire became intelligible when the 

 great French savant Lavoisier made it clear that a 

 burning substance unites with oxygen from the air and gives off 

 an acid carbonic-acid gas. He proved with his fine balance that 

 the increase in the weight of the substance burned corresponded 

 to the loss in weight in the surrounding air. This does not sound 

 very exciting nowadays, but it was epoch-making. For Lavoisier 

 realised that in all chemical operations it is only the kind of matter 

 that is changed, the quantity remaining the same. 



The Conservation of Matter 



This was the discovery of the CONSERVATION OF MATTER, 

 one of the foundation stones of chemistry, and not only a founda- 

 tion stone, but a touchstone of accuracy, for it was henceforth 

 certain that in every chemical operation the accounts must bal- 

 ance. The total mass of the substances taking part in any chemi- 

 cal operation remains constant, no matter what kaleidoscopic 

 transformations may be effected. Since the masses of bodies are 

 at any one place exactly proportional to their weights, the 

 fundamental idea may read that in any series of chemical opera- 

 tions the weight at the end must equal the weight at the beginning. 

 When Lavoisier made one of his famous experiments of passing 

 water-vapour over red-hot iron turnings, and collecting the hydro- 

 gen which was thus produced from the water, he weighed every- 

 thing the water to begin with, the iron turnings before and after, 



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