Inventions resulting from discoveries. 17 



ways the numerous manufacturing, agricultural, and 

 other processes in which that substance operates. 

 Priestley made many experiments also on the absorp- 

 tion of gases by water, and proposed the resulting 

 liquids as beverages ; and those apparently trifling 

 experiments have since expanded into the large 

 manufactures of aerated waters. The discoveries of 

 gutta-percha and india-rubber were indispensible to 

 the great applications of those substances in tele- 

 graph cables, and in a multitude of useful articles. 

 The discovery of chloroform and anaesthetics has led 

 to their use for the purpose of alleviating human 

 suffering. The discovery, by Sir Isaac Newton, of 

 the decomposition of light by means of a prism, has 

 led in recent times to the invention of the spectro- 

 scope; to the use of that instrument in the Bessemer 

 steel process ; to the discovery of a number of new 

 metals, thallium, rubidium, caesium, indium, and 

 several others, and to the most wonderful discovery 

 of the composition of the Sun and distant heavenly 

 bodies. 



Even the invention of the steam-engine was partly 

 a consequence of previous researches made by scien- 

 tific discoverers. Watt, himself, stated in his pam- 

 phlet, entitled "A plain Story," that he could not 

 have perfected his engine had not Dr. Black and 

 others previously discovered what amount of heat/ 

 was rendered latent by the conversion of water into 

 steam. " Each mechanical advance in the steam- 

 engine has been preceded by and the result of the 



