238 PLASTER OF PARIS. 



town, and the soil is a heavy loam : some parts of the 

 pasture, which is hilly land, are ledgy, and the ledges 

 have formerly been covered with moss. Plaster here 

 has the effect of bringing up clover through the moss ; 

 and the cattle are so fond of this new growth, they 

 often destroy all the moss in search of it. 



It seems philosophical to suppose that plaster ope- 

 rates to most advantage in soils that are naturally de- 

 ficient of the article. We cannot rank it with the 

 manures : they are beneficial to all soils. It probably 

 acts as a stimulant to other matter. It attracts mois- 

 ture from the atmosphere, and acts as a solvent on the 

 surface of soils that are liable to be baked in the sun 

 and to crack open ; hence it is more serviceable in dry 

 seasons than in wet ones. It is better on the surface 

 than underneath. 



There is much difference in the quality of the article 

 sold as plaster. We have often thought that best 

 which contained the most sulphur. We test it by 

 boiling it in a kettle ; and, when hot, it will be so light 

 it may be stirred as easily as hasty-pudding, when 

 only half thickened. If it be good, it then emits a 

 strong flavor of sulphur. 



It has been objected that plaster tends, in the end, 

 to impoverish the soil ; that it sends out a forced 

 growth by its stimulating power, and then leaves the 

 land poorer than before. The same objection has been 

 made to ashes ; that they stimulated, but did not 

 enrich. 



We cannot agree to such doctrine. We might as 

 well say that showers of rain Vv^ere useless because 

 they merely stimulate other matter. Any thing which 

 vvTill produce a large vegetable growth may readily be 

 converted into manure, by means of the plough. The 

 more we make our fields produce, the more ability 

 we have to go on increasing our crop from year to 

 year. 



