On Plaister of Paris, 111 



will produce good effects; but in all cases where the 

 acid prevails, it will certainly do harm, 



" This account of the nature of gypsum we are en- 

 abled to give, from having carefully examined different 

 sorts of it. In some of these the calcareous earth pre- 

 vailed ; and in others the substance was a neutral com-, 

 pound. We pronounce, therefore, that in all cases where 

 the calcareous earth prevails in gypsum, it will be usC' 

 fuly if the ground has not been previously limed. 



In cases where the acid and earth are equally balanc- 

 ed, it will have other effects. 



And in cases where the acid prevails, it will uniformly 

 do harm ; unless, perhaps upon chalk or limestone lands. 



It is therefore a manure that can seldom be used 

 with advantage in this country upon arable lands, as 

 there are few situations indeed in which the soil does 

 not either contain calcareous matter in itself or has re^ 

 ceived it as a manure." 



OBSERVATIONS. 



THE writer of this article is misinformed when h& 

 says that " in America scarcely a particle of calcareous 

 earth is to be found.'''' We have enough of it, mixed 

 with a great variety of substances. Our attention has 

 not been sufficiently paid to subterraneous explorations, 

 to enable us accurately to class or designate the seve- 

 ral species, either of those unmixed, or in combination. 

 We know most about the argillaceous (clayey) earths, 

 because we have had them more in use, and they are 

 more common. This account of gypsum, as to its agri- 



