86 On Plaster of Paris ', 



XXIII. On the Use of Plaster of Paris (different 

 varieties of Gypsum, or Sulphate of Lime), as a 

 manure, in Virginia. In a Letter to the Editor, 

 from his Brother, Mr. Richard P. Barton, of 

 Frederick- County, Virginia. 



THE use of Plaster of Paris is becoming 

 more and more general. It is found to answer well 

 upon some of our soils, particularly such as are dry, 

 friable, and contain white flint ; also upon what are 

 termed slate-lands. In such soils as are highly cal- 

 careous, I think little, if any, effect is produced. On 

 my own farm, which contains much of the latter soil, 

 the effect of plaster is never visible ; but on my slate- 

 lands, adjoining the limestone, the influence of plaster 

 is great, particularly on clover. 



i 

 It is my opinion, that it never produces any visible 

 effect upon lands that are highly calcareous. This 

 theory is contradicted by many persons here, who say, 

 that it has much benefited their crops, although their 

 lands are limestone-lands. But, in fact, at least half the 

 mii face soil of lands denominated limestone is not cal- 

 careous, or contains calcareous earth in small quan- 

 tity. Upon inquiry, in every instance, I am told, that 

 the effect of plaster is greatest upon the poorer or 

 thinner soils, in the intermediate spaces between the 

 beds or ledges of limestone. These poor spots gene- 

 rally lie higher than the beds of limestone, and can- 

 not, therefore, receive the washings from them. Their 

 complexion, which is generally pale, proves, that 



