THE CHEMISTRY OF BOG RECLAMATION. 201 



ricks that have been stacked when imperfectly dried ; in the 

 spontaneous combustion of damp cotton in the holds of ships, 

 and in factories where cotton-waste has been carelessly heaped ; 

 and in cucumber-frames and the other " hot-beds" ot the 

 gardener. 



In ordinary soils this combustion goes on more slowly, but 

 no less effectively, than in these cases. In doing so it main- 

 tains a certain degree of warmth about the roots of the plants 

 that grow there, and gradually sets free the soluble salts which 

 the rotting vegetables contain, and supplies them to the grow- 

 ing plants as manure, at the same time forming the humus so 

 essential to vegetation. 



A great excess of water, such as soddens the bog, prevents 

 this, and also carries away any small quantity of soluble nutri- 

 tious salts the soil may contain. Thus instead of being warmed 

 and nourished by slight humidity, and consequent oxidation, 

 the bog soil is chilled and starved by excess of water. 



The absolute necessity of the first operation that of drain- 

 age is thus rendered obvious ;- and I suspect that the need of 

 four years' rest, upon which Mr. MacAlister insists, is somehow 

 connected with a certain degree of slow combustion that accom- 

 panies and partially causes the consolidation of the bog. I 

 have not yet had an opportunity of testing this by inserting 

 thermometers in bogs under different conditions, but hope to 

 do so. 



The liming next demands explanation. Mr. Henry says that 

 " it leaves the soil sweetened bv the neutralization of its 

 acids." 



In order to test this theory I have digested (i.e. soaked) vari- 

 ous samples of turf cut from Irish bogs in distilled water, 

 filtered off the water, and examined it. I find that when this 

 soaking has gone far enough to give the water a coloring, simi- 

 lar to that which stands in ordinary bogs, the acidity is very 

 decided quite sufficiently so to justify this neutralization the- 

 ory as a partial explanation. There is little reason to doubt 

 that the lime is further effective in enriching the soil ; or, in 

 the case of pure bogs, that it forms the soil by disintegrating 

 and decomposing the fibrous vegetable matter, and thus render- 

 ing it capable of assimilation by the crops. 



Another effect which the lime must produce is the liberation 

 of free ammonia from any fixed salts that may exist in the bog. 



The bog-burning method of reclamation is easily explained. 

 In the first place, the excessive vegetable incurnbrance is 



