168 ON THE IMPROVEMENT OF SOIL. 



difficult and laborious carriage. The Isle of Thanet owes 

 its reputation in a great measure to the power of procur- 

 ring this manure. And the sea-salt they contain is also 

 favorable to vegetation. Straw is an excellent ingredient 

 for manure ; but it requires being mixed with animal ma- 

 nure, or stratified with earthy matter. Bark and sawdust 

 are occasionally used for manure : they should, however, 

 with greater propriety be considered as materials for im- 

 proving the soil, as they afford but little nourishment. 



The grain which produces oil, such as linseed, rape- 

 seed, &c., makes excellent manure after the oil has been 

 expressed : in this state it is called oil-cake, and its unc- 

 tuous qualities serve to accelerate decomposition ; but in 

 England it sells at such a price as to make it a doubtful, 

 speculation even to feed cattle with. It would be too' 

 expensive to be used as manure. 



Emily. Pray, would not soot make very good manure ? 

 It is almost pure carbon, in so highly a pulverised state, 

 >as must render it fit to enter into the vegetable system. 



Mrs. B. You forget that it is first necessary to com- 

 bine it with oxygen ; and this is a work of time. Soot 

 has, however, an immediate beneficial effect, though not 

 a very permanent one : it is used in large quantities in 

 Hertfordshire, both for grain and pasture, and is strewed on 

 the land in March and April, for the crop of the same year. 



Caroline. I recollect having observed that the envi- 

 rons of the spots, where charcoal has been prepared in 

 the mountains, are absolutely destitute of vegetation, al- 

 though strewed with charcoal-powder. 



Mrs. B. But were you to visit these same spots some 

 few years afterwards, you would find vegetation more 

 flourishing, more vigorous, and especially greener than 

 elsewhere, because the charcoal-powder will have gradu- 

 ally combined with the oxygen of the atmosphere, and thus 

 vegetation be luxuriously supplied with its favorite food, 

 carbonic acid. 



The most common manure consists of a mixture of ani- 

 mal and vegetable materials ; and this, again, is frequent- 

 ly stratified with mineral substances, such as mud from 



924. What is said of sea-weed used as manure 1 925. And of 

 bark and sawdust'? 926. What grains are good for manures'? 927. 

 What is said of oil cake! 928. What is said of soot, as a manure 

 in Hertfordshire'? 929. What is seen to take place, where char- 

 coal is prepared 1 ? 930. Of what does the most common manure con- 

 sist? 



