QUESTIONS; 343 



214. What is the estimated amount of coal in all the coal-fields of 

 North America? What of all in Great Britain ? In Belgium ? In 

 France ? What facts are stated about the introduction of anthracite 

 into full use in this country ? What estimate is made of the length 

 of time the coal of this country will last? What statements are 

 made about the extent of coal-fields ? 



215. Describe the arrangement of the carboniferous strata. What 

 are called the coal-measures ? In what way do the rocky strata in 

 these measures differ from other rocks ? Of what practical value is 

 the knowledge of this difference ? What does Hitchcock say on this 

 point ? What is the under-clay, and what is said of it ? What is the 

 proportion of coal to rock in the coal-measures ? 



216. What is the sub-carboniferous period? What is the thickness 

 of the floor of the coal-measures laid in this period ? Of what was 

 it made ? What is the relative position of the sub-carboniferous and 

 carboniferous strata ? What similarity of arrangement was there in 

 the Silurian and Devonian ages and the sub-carboniferous period? 



217. In what two respects did this arrangement differ in the sub- 

 carboniferous period from that of the Silurian and Devonian ages ? 

 What is the difference between the burning of wood and the making 

 of charcoal? Explain the chemistry of the formation of coal. Why 

 is this process called eremacausis ? What is said of the decay of veg- 

 etable matter ? 



218. What is said of the agency of pressure in making coal ? What 

 is the difference between bituminous and non-bituminous coal ? What 

 is the flame of bituminous coal ? What that of imperfectly burning 

 anthracite ? How is it supposed that anthracite was produced from 

 bituminous coal? How does it differ from coke? What is said of 

 the vegetable growth from which coal was formed ? 



219. What is said of the accumulation of material for a coal-bed? 

 Describe what took place after all the material was deposited. What 

 is stated about the number of coal-beds ? What does Hugh Miller 

 say of the alternate subsidences and elevations of this age ? 



220. What is said of the impurities of coal ? What of the calcula- 

 tions as to the time required for the formation of the coal-measures ? 

 What of the plants whose remains are found in them ? 



221. What is said of the remains of leaves found in the rocks? 

 State the experiments of Professor Goppert. 



222. What is said of the Calamites ? What of Sigillaria and Stig- 

 maria ? 



223. What of the Lepidodendron ? What of the Ferns ? 



224. What of the Conifers? 



225. What is the general view given of carboniferous vegetation ? 



226. What does Page say of the beauty of this vegetation ? What 



