QUESTIONS. 281 



Whence clay? Lime? 270. &quot;Weathering? How does heat ac-t? 

 rain ? frost ? What else are acting ? What action has water ? 280. 

 The best natural soil ? Most fertile soils ? 281. Basis of all soils ? A 

 clayey sand ? A sandy clay ? Loamy clay ? 282. What must be 

 added to all these to form a good soil ? How does humus .act ? Hu 

 mus ? What is land which contains four per cent, of it ? eight ? ten ? 

 283. How may it be found whether humus is present in a soil ? 284. 

 When, only, is humus unfavorable to useful vegetation ? How must 

 they be corrected ? 285. How does humus act ? What are succes 

 sively produced ? 286. What action has the carbonic acid ? The oxy- 

 gvn ? 287. What other important property ought a soil to have? 

 What will give this property ? 288. The richest natural soils ? Where 

 are such soils found ? Describe the formation of these soils ? In 

 what parts are the most fertile of such soils found? 289. The soils 

 next in value ? Why ? 290. Of what are granite, gneiss, and mica 

 slate, composed ? Syenite ? Trap-rock ? Greenstone ? Porphyry ? 

 Examine the table and give it on the black-board. 291. Quartz? Fel 

 spar ? Mica ? Hornblende ? Augite ? 292. What is to be done when 

 clay can easily be had ? An amendment ? i$3. A more effectual way 

 of rendering sandy soil fertile? Where is this to be found? How 

 does it act ? Describe it. What will be the effect of this process 

 repeated ? 294. What substitute can be found for clay and marsh 

 mud ? 295. What do these amendments require ? 296. How is a 

 clayey soil to be improved ? When may this be done ? Effect of the 

 sand ? How else ? 297. How may a calcareous soil be amended ? A 

 fourth kind of soil ? They really ? How are they to be managed ? 

 299. What manures are good for such a soil ? 300. Heavy, cold soils ? 

 Why are wet lands cold? 301. Effect has color? Dr. Franklin s 

 experiment ? 302. Is our soil formed by the crumbling of rocks just 

 beneath the surface ? Diluvial soils ? When the forests are cut down 

 what kind of soil is usually found ? How fertile ? How has this soil 

 been formed ? 304. Give instances of the effect of weathering. Of 

 oxygen ; carbonic acid ; in water. How powerful is its action ? 306. 

 How else does CO 2 act? How do the alkaline carbonates act? 308. 

 The remedy for the loss of fertility ? 309. Is a soil barren for one 

 plant also barren for every other ? 



CHAPTER X. 310. Subsoil ? 311. Its influence? What is to be 

 done? Why should it be done gradually? 312. When should the 

 subsoil be mixed with the soil ? Evils of a subsoil impermeable 

 to water? The remedy? 313. Indications of this evil? Remedy? 

 Kule? 



