Sec~l. V. Agriculture and Vegetation. 83 



PUTREFIED fubftances are all of an al- 

 kaline nature. The alkaline fait is often 

 indeed invifcated by the oily parts, fo that 

 it can fcarcely efTervefce with acids. This 

 has led fome to aflert, that putrefied fub- 

 ilances were not alkaline ; an aflertion op- 

 pofite to experiment. We know with what 

 a gentle heat the volatile falts of putrefied 

 bodies rife ; a heat incapable to form thofe 

 falts, if they did not pre-exift ; but capable 

 of raifing them when once formed. As 

 pigeons dung is the ftrongefl of all dungs, 

 for vegetable and animal fubflances are the 

 fame when putrefied, the alkaline falts are 

 moft obfervable in it. I have feen the fur- 

 face of that dung covered with a white fait, 

 which fmelt as ftrong as the volatile fait of 

 hartmorn. Every one is fenfible of his 

 eyes watering, when he goes into a pigeon- 

 houfej owing to the pungent volatile falts 

 in the air. Subftances highly putrefied ef- 

 fervefce with acids. Reaumur, Ipeaking of 

 the leaves of the vine, which he had fet 



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