454 TRANSACTIONS OP THE AMERICAN INSTITUTE, 



never was a clay soil which was not acted favorably upon by 

 its application. You do not have so sudden an action as in 

 sandy soils ; but there is an effect and it can be seen in every 

 crop. 



The paring and burning of land, I have seen fail, and where 

 it contains iron, the harm it does from the change of its form is 

 greater than the benefit of burning. But when there is no excess 

 of iron in the soil, then using the paring plow and burning the 

 surface, and afterwards sub-soil plowing and. using the burned 

 paring as manure, may renovate the soil and produce good results. 



The value of ashes from burning the surface of bogs or swamps 

 is less, for the reason that the plants there produced are lower 

 organisms, and, therefore, the inorganic matter left after the 

 burning, although it had been once in solution, and was suffici- 

 ently progressed to enter into organic life, yet belonged to lichens 

 and mosses, lower forms in the scale of progression. Some bogs 

 would perhaps produce an ash worth ten cents per bushel ; while 

 others would yield a far inferior kind. 



PLASTER or PARIS. 



I would direct your attention here particularly to the difierence 

 in the value of plaster obtained from different sources. Take 

 native plaster, grind and apply it, and the reason why it acts as 

 well as it does, is that so little plaster is called for by certain 

 crops. But take plaster that has been burned, such as is used 

 in the plastering of buildings, and one bushel will take the place 

 of twenty bushels of rough rock. Plaster that is made by treat- 

 ing bones with sulphuric acid, where the lime of the bones is 

 converted into the sulphate of lime, or plaster, has a high value 

 to any farmer to the extent that his crops call for plaster. It 

 is taken up with very great ease. The French have found that 

 taking plaster which has been exposed to atmospheric influences, 

 such as that taken from ceilings made from Plaster of Paris, and 

 grinding it fine enough, one bushel will have much more effect in 

 preparing for clover than plaster not so exposed would have. 

 The native Plaster of Paris is found underlying the city of Paris. 

 When you treat any organic matter containing lime with sul- 

 phuric acid, the sulphate of lime, then formed, has an immense 

 value. It is more valuable than the phosphate in that condition. 

 We find that some chemists in making analysis of manures, con- 

 sider the sulphate of lime as valueless, because it happens to 



