FLAME. 225 



558. COLLECTION AND DISTRIBUTION. 

 After purification, the gas is collected in 



lectedand dis- } e n . on holders, called easrmeters. 



tributed ? 



Tiiese may be represented by the inverted 

 tumbler of the figure. Gas pouring 

 in from below would lift and fill it. <^TS^ 



If an orifice were made in the top, 

 the tumbler would immediately set- 

 tle into the water. The air would, 

 at the same time, escape through the 

 orifice. The distribution of illumina- 

 ting gas, from public gas works, is effected on the 

 same principle. The weight of the sinking gas- 

 ometer, is sufficient to press it through pipes, to all parts 

 of a large city. 



559. GAS FROM WOOD. Gas may be 



How may gas 



be made from made from wood, by the same means 

 above given. Only a moderate heat is re- 

 quired, in this case, to produce tar at the same time. 

 Gas of higher illuminating power than that prepared 

 from wood or coal may also be made from oil fat or 

 rosin. Even refuse vegetable substance may be em- 

 ployed. A pound of dried grape skins have been found 

 to yield 350 quarts of excellent illuminating gas. The 

 dried flesh of animals has sometimes been employed 

 for its manufacture. 



FLAME. 



What is said 560. FLAME. Nothing in nature is, to 

 of flame ? t j ie un i ns t rilc ted eye, more mysterious than 

 flame. It is, seemingly, body without substance, and 



10* 



