314 MODERN SCIENCE READER 



other things; but it is the oxygen that gives the principal 

 difficulty. When the compound of iron and oxygen is 

 heated with something that, under the circumstances, has 

 the power to combine with the oxygen and escape with it 

 in the form of a gas, the iron is left behind. Charcoal or 

 coke is used for this purpose. At high temperatures, these 

 substances, which are different forms of the element car- 

 bon, take the oxygen from the iron, and the metal liberated 

 sinks to the bottom of the furnace in the molten state, while 

 the gaseous compound of carbon and oxygen passes out of 

 the top of the furnace. The oxygen changes partners. It 

 is to be observed that the iron ore might be mixed with the 

 charcoal, and the mixture allowed to stand at ordinary 

 temperatures for any length of time, without separation of 

 iron. Heat is necessary, and a good deal of it, to cause the 

 charcoal to unite with the oxygen and carry it off into 

 space. 



Heat being an important factor in chemical acts, the ques- 

 tion suggests itself: What will be the effect upon chemical 

 processes if the temperature is raised much above the range 

 within which we ordinarily work? And at the same time 

 the complementary question will suggest itself: What will 

 be the effect of lowering the temperature much below that 

 at which we ordinarily work? 



EXTREMES OF TEMPERATURE 



Until within the last few years the highest temperatures 

 attainable were reached by the aid of the so-called compound 

 blowpipe, which is an instrument for burning hydrogen, 

 or some other combustible gas, in oxygen under pressure. 

 By the aid of this instrument platinum was melted and, 

 in one case, silver was boiled. But now the introduction 

 of powerful electric currents has made the production 

 of much higher temperatures possible, and marvelous re- 

 sults have been reached. M. Moissan, of Paris, has for 

 some time been engaged in studying the chemical effects 

 of high temperatures, and to him we owe almost all wo 



