DISCOVERY BY MEANS OF NEW EXPERIMENTS. 541 



analysis, and discovered that the proportions of the ingre- 

 dients of substances were definite ; and observing that 

 when two neutral salts decomposed each other the result- 

 ing salts were also neutral, he was led to the discovery 

 that the definite proportions were reciprocal. It was by 

 means of the experiment, of burning a diamond in oxygen 

 gas that Lavoisier, about the year 1778, discovered that 

 that gem was composed of carbon alone. By burning 

 charcoal also in oxygen, and analysing the product, he 

 discovered that ' fixed air ' was composed of twenty-eight 

 parts by weight of carbon and seventy-two of oxygen ; and 

 having found that most substances, by union with oxygen, 

 acquired acid properties, he called ' fixed air ' by the name 

 of carbonic acid. Warltire, in 1781, by exploding a mix- 

 ture of atmospheric air and hydrogen in a closed vessel, by 

 means of an electric spark, discovered, after the experi- 

 ment, what he considered to be water adhering to the 

 inner sides of the vessel. Cavendish, by means of similar 

 experiments made in 1784, with a mixture of oxygen and 

 hydrogen, discovered the formation and composition of 

 water. Fourcroy, Vauquelin, and Seguin, by means of a 

 continuous series of such experiments with that mixture, 

 lasting from May 13 to 22, in the year 1790, discovered 

 that it produced a nearly equal weight of water. Kitchie 

 also, in 1792, discovered what the proportions were of the 

 common acids and bases which would saturate each other. 

 By tying an artery and vein, and observing the 

 mechanical effects upon the two sides of their tied parts, 

 Harvey, in the year 1619, was led to suspect, and ulti- 

 mately to discover, the circulation of the blood. It, how- 

 ever, required nineteen years of experiment and study 

 to enable him to trace the entire course of the blood 

 through the whole of the human body, and completely 

 prove his discovery. It was by means of actual experi- 



