undergoes when in contact with Vegetables. ■ 237 



volume of air had not undergone any sensible change, and that 

 it was much less vitiated than in the previous experiments. In 

 fact, the receiver contained, before the experiment, of nitrogen 

 23.05, of oxygen 6.12, = 29.17; after the experiment, of nitro- 

 gen 23.05, of oxygen 5.25, of carbonic acid .87, — 29.17. 



It is here to be remarked, that these fuzz balls, taken in the 

 state we have mentioned, are much more liable to fermentation 

 and spontaneous decomposition than when they are young and 

 in a fleshy state. Does not this result serve to demonstrate that 

 the large quantity of carbonic acid produced in the two first 

 experiments is an effect of vegetation properly so called, and 

 not the result of commencing decomposition and fermentation, 

 as at the first glance might appear ? In allowing that decom- 

 position was the cause, we should have found the air more vi- 

 tiated in the last experiment, when the mushrooms were nearly 

 approximating to it, than in the former two, when they were 

 very fleshy, and in that state in which their vitality is the 

 greatest. 



2d Experiment. — Three mushrooms, growing close together, 

 of' the species Agaricus amarus, and weighing together sixty 

 grains, were introduced into a receiver, which contained 19.54 

 cubic feet of air ; the thermometer standing at 68° Fahr. At 

 the end of nine hours the volume of air in the receiver had not 

 undergone any sensible change ; its composition was as follows : 

 — The receiver contained, before the experiment, of nitrogen 

 15.44, of oxygen 4.08, = 19.52; after the experiment, of nitro- 

 gen, 15.46, of oxygen .53, carbonic acid 3.55, = 1954. 



It will be observed, that in this experiment thiire does not ap- 

 pear to have been any evolution of carbonic acid already formed 

 from any of the plants, since the quantity of carbonic acid gas 

 which was disengaged coincides exactly with the quantity of 

 oxygen which was absorbed. 



This experiment, repeated for twelve hours during the night, 

 afforded a result which scarcely at all differs from the above, 

 and it is therefore unnecessary to state the details. 



2d Experiment. — Three mushrooms, belonging to the spe- 

 cies Agaricus campesiris, and together weighing 190 grains, 

 were placed under a receiver inclosing 35.58 cubic feet of air ; 



VOL. XIX. NO. XXXVIII.— tlCTOBKU 1835. R 



