226 



MANURES. 



Sect. X. 7,^, 



that the heat emitted from the burnnig vegetable fibres unites oxygen 

 with the clay ; \^ 



hich 



r forms more th 



half 



f th 



fl 



of 



f, as they are dug from the ground. In other i-efped:s the pa 



d burning of 



grafs grounds would certainly be a wafbeful 



o 



proce 



dure ; as much carbon is converted into carbonic acid, and difperfed 

 along with the uninflamed fmoke or foot, and nothing left but the 



getable a(h 



F 



m 



thefe 



fiderat 



it would probably be 



d 



ay 



abound, to bu 



& 



hich mig 



fupply 



xhauftlefs 



worthy experiment in farms, wh 



the latter to a certain dr~ • 



fource of profitable manu 



5. I have fufpeded alfo, that this calcined clay, as it exifts in foft 

 bricks, has a power of decompofing marine fait, as I once obferved 

 in a cellar, where beef had been Ions: falted on one fide of a nine-inch 



wall, the wooden falting-tub for which was attached to it 



th 



a 



o 



fflorefcence appeared on the other fide of the wall, which I 



believed to be fofEle alkal 

 bricks from old buildii 



If th 



idea be juft, the foft 



\^ 



or clays fo far purpofely b 



may 



this manner be ferviceable 



o 



by feparating the foflil 



kali from the fea-falt, which is wafhed from decompofing animal and 

 vegetable fubftances ; which by converting carbon into an hepar car- 

 is fuppofed to do in No. 6. i. of this Se6lion, might 



bon 



ime 



der it folubl 



in water, and capable of being abforbed by th 



lymphatic vefTels of 



of pi 



If clay calcified to a certain degree, and thus united with oxygen, 

 pofTefTes the power of decompofing marine fait, there is reafon to 



believe, when it is more flowly united with oxygen by its expofure 



to the atmofphere by the fpade or plou 



CT 



that it may pofTefs the 



fame property ; and that this may have given rife to the very con- 

 tradictory reports concerning the ufe of fea-falt in agriculture ; as it 

 may probably be of great advantage to clayey foils, but perhaps 

 not fo to other foils. See Seel. XIV. 2. 8. 



6. Another faline body, which readily unites with argillaceous 



earth 



