THE SOUTHERN PLANTER 



269 



if it contain a large amount of feldspar. 

 Porcelain clay, which is found in such 

 large quantities in this count}^ is obtained 

 from the decomposition of granite, and 

 what is called china-stone is simply gra- 

 nite partially decomposed. Now what is 

 the nature of the action of the air in this 

 case ? There is a certain principle in the 

 air called carbonic-acid gas, which acts 

 upon the potash in the feldspar, and dis- 

 solves it out; and of course, the effect of 

 dissolving the potash is just like that of 

 taking the mortar out of a wall — the other 

 materials fall to pieces. If in the district 

 of St. Austle parties did not wash out the 

 clay in order to use it for various artifi- 

 cial purposes, the rain which falls from 

 heaven, and the continual action of the 

 air, would eventually produce the same 

 result. And without entering into any 

 description of other substances similar to 

 feldspar, I would simply observe that the 

 general origin of clay soils in the decom- 

 position of substances containing alumina 

 in quantities. While you find the alumina 

 which is a very light substance, wash- 

 ed down into one part, you have the si- 

 licious matter washed down into another 

 part; and this disintegrating and washing 

 process on different rocks goes on until you 

 get every variety of soil that can be con- 

 ceived, from a clay to a sharp sand. Well, 

 now, having seen that soils owe their pri- 

 mary origin directly to the disintegration ( 

 of rocks, of which there is such an abun- 

 dance in Cornwall, let us now proceed to 

 consider the effect of atmospheric action 

 upon soils themselves when they have 

 been formed. Now, gentlemen, there are 

 certain substances in the soil, which are, 

 as I have before intimated, soluble : pot- 

 ash, soda, lime, magnesia, phosphate of 

 lime, &c, are some of them. These sub- 

 stances are continually acted upon in the 

 soil by the air — that is to say, they are 

 liberated from their insoluble combinations 

 in a soluble form, provided, the air acts 

 upon them ; while in the absence of at- 

 mospheric action they are not rendered 

 soluble. Thus we at once see the neces- 

 sity of exposing the land to the air by 

 ploughing, by harrowing, and by every 

 other mechanical means that is suitable, 

 in order to secure the liberation of those 

 substances which are essential to the 

 growth of plants. In order, gentlemen, 

 that the soils of any given district may be 



properly tilled, it is necessary that they 

 should be regularly exposed to the action 

 of the air, that they should be properly 

 drained, and that if lime be absent it should 

 be supplied in sufficient quantity. Let 

 me' — taking these points in the order in 

 which I have mentioned them — first speak 

 of the action of the soil upon the air. 

 Every substance— -a piece of chalk, for 

 example, has a certain amount of surface,, 

 and the surface of every solid body at- 

 tracts air and moisture. It has been prov- 

 ed that there is more air and more mois- 

 ture within the 100th part of an inch from 

 the surface of this glass [holding up a tum- 

 bler] than within the second 100th part ; 

 the truth being that the surface of any 

 solid body attracts aeriferous matter. You 

 would hardly imagine, but it is neverthe- 

 less a fact, that a piece of charcoal like 

 this [exhibiting a piece] would, if expos- 

 ed to ammonial gas, absorb 90 times its 

 own volume of that gas. This piece of 

 chalk has now a certain surface. If I 

 break it, it will have two surfaces ; if I 

 break it again, it will have two more. And 

 as the absorbent power of any substance 

 depends upon the extent of surface, so, 

 you perceive, the more you pulverize your 

 land the greater must be the extent of sur- 

 face which }'ou expose to the action of the 

 air. (Cheers.) Every division that you 

 make exposes a greater amount of surface, 

 and the finer the division is, or, to use a 

 phrase which is common in another part 

 of the kingdom, if not here, the finer tilth 

 you make, the better the land will be 

 adapted for the growth of plants. I again 

 repeat, all solid bodies have the power of 

 absorbing the liquid and gaseous bodies 

 which are found in the air. Thus you 

 have the ammonia absorbed from the air; 

 and all the other materials in the air which 

 are required for the proper development 

 of the plant — you have all these absorbed 

 by the finely pulverized soil, and you have 

 that soil at the proper time liberating those 

 substances for the roots of the plant. Let 

 us take a case in point — a case which will 

 serve to illustrate the necessity of stirring 

 up the land in order to its proper cultiva- 

 tion. I will suppose that you have a field 

 of turnips. In such a season as the last, 

 when there was a considerable amount of 

 dry weather, you might perhaps have con- 

 siderable amount of dry weather, you 

 might perhaps have considered it was not 



