On Plaister of Paris, 99 



now in excellent common grass ; intermixed with red 

 and white clover, and some blue grass — parts of it 

 much layed, owing to the wet season. 



I have, from this and many other occurrences, long 

 been of opinion, that the plaister must come in con- 

 tact with some animal or vegetable manures, or pu- 

 trefied substances, /^^^ to give it its proper efficacy. 



{tj " Charcoal or carbon exists ready formed in vegeta- 

 bles, Chaptal 36, 37." 



Although Chaptal, page 452, asserts, that " we see the 

 vegetable almost entirely formed of hydrogene^ he, in the 

 the same page says "the nitrogenous gas (and he afterwards 

 adds the carbonic acid) more particularly serves them for 

 aliment. " Hence it arises that vegetation is more vigorous 

 when a greater quantity of these bodies which afford this gas^ 

 are presented to the plants these are animals or vegetables 

 in a state of putrefaction. " Carbonic acid predominates in 

 the fungus, and other subterraneous pla?its.^^ Page 453. Ingen- 

 hausz on the food of plants, 6. "^// manures, principally dung, 

 produces a great quantity of the carbonic acid, either by itself, 

 or by decomposing the air in contact with it." Hassenfratz 

 asserts, that the brown sediment of dung is carbone. And 

 Ingenhausz, though he does not exactly agree with Hassen- 

 fratz, allows that this brown sediment may become carbone 

 by ignition. It appears then that the gases, which are the 

 food of plants, according to the present theory, exist in vege- 

 tables ready formed ; and in animal or vegetable substances 



with dung. I must be understood here to mean, a repetition 

 of the plaister. For in the first application, it has generally 

 thrown up as great a burthen, as any combination could pro- 

 duce. 



