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foil to approach to the nature of that of Upfal, the fall of rain 

 being probably between 24 and 28 inches. In 1792, which was 

 reckoned remarkably wet, it was 30.^ inches in Dublin. 



Before I quit the experiments of Mr. TiUet it will be proper 

 to mention a few made by him, which feem to invalidate the 

 neceffity of the prefence of the three fimple earths in fertile 



iOll 



I""- In his 26th experiment he tells us he employed only pure 

 fand, fuch as is ufcd for making glafs, yet corn grew well in it 

 the firft year, indifferently the fecond, and nearly failed in the 

 third. Mr. Haffenfraz having repeated the experiment in pots 

 unperforated did not find it to fucceed even the firft year, there- 

 fore the fuccefs of Mr. Tillet's was owing to the perforation at 

 the bottom of his pot through which water impregnated with 

 the different earths, and coal muft have palfed. In fad Mr. 

 Tillet's conclufion is contradidled by univerfal experience. 



2°- In his 28th experiment, in which powdered limeftone 

 only was employed, the corn fown profpered exceedingly during 

 the three years. To the caufc mentioned, in treating of the 26th, 

 I muft add, that the limeftone he ufed was that of St. Leu, 

 which contains clay, and confequently filex and argill ; it is fo 

 porous as to admit from ^^V to > of its weight of water, as Mr. 

 Briffon has fticwn, and thus is eafily decompofed. The coarfe 

 powder to which it was reduced anfwered the fame purpofe as 

 coarfe filex, and the finer might nourifh the plants. 



Z 2 3'- I^- 



