4:2 SCIENCE IN SHORT CHAPTERS. 



pact, is not porous, and therefore, of course, much denser, a 

 given weight occupying less space. 



That we Englishmen should be about the last of all the 

 coal-using peoples to apply anthracite to domestic purposes is a 

 very curious fact, but so it is. In America it is the ordinary 

 fuel, and this is the case in all other countries where it is 

 obtainable at the price of bituminous coal. Our perversity in 

 this respect shows out the more strikingly when we go a little 

 further into the subject by comparing the two classes of coal 

 in reference to our methods of using them, and when we con- 

 sider the fact that our South Wales anthracite is far superior 

 to the American. 



Our open fires only do their small fraction of useful work by 

 radiation. Their convection is all up the chimney. Such 

 being the case, and we being theoretically regarded as rational 

 beings, it might be supposed that for our national and espe- 

 cially radiating fireplaces we should have selected a coal of 

 especial radiating efficiency, but, instead of this, we do the 

 opposite. The flaming coal is just that which flings the most 

 heat up the chimney, and the least into the room, and, as 

 though we were all struggling to destroy as speedily as possi- 

 ble the supposed physical basis of our prosperity, we select 

 that coal which in our particular fireplaces burns the most 

 wastefully. If we had closed iron stoves with long stove- 

 pipes in the room, giving to the air the heat they had obtained 

 by the convectivc action of the flame and smoke, there might 

 be some reason for using the flaming coal, as the flame would 

 thereby do useful work, but, as it is, we stubbornly persist in 

 using only the radiated heat, and at the same time select just 

 the coal which supplies the smallest quantity of what we 

 require. 



No scientific dissertation is necessary to prove the superior 

 radiating power of an anthracite fire to anybody who has ever 

 stood in the front of one. This is most strikingly demonstrated 

 by those grates that stand well forward, and are kept automat- 

 ically filled with the radiant-carbon. 



Let us now see ivhy anthracite is a better radiator than 

 bituminous coal. This is due to its chemical composition. 

 Of all the substances that we have upon the earth carbon in its 

 ordinary black form is the best radiator. Anthracite contains 

 from 90 to 94 per cent, of pure carbon, bituminous coal from 

 70 to 85, and much of this being combined with hydrogen 

 burns away as flame. On a rough average we may say that 



