ON THE VEGETATION OF PLANTS. 151 



whenever they appear to afford oxigenousgas, it is by devour- 

 ing the coal of carbonic acid gas for food, and leaving its ox- 

 igen in the form of pure air. 



I have the honour to be, 

 Dear Sir, 



With the greateft refpect, 

 Your mod obedient, 



And very humble fcrvant, 

 JAMES WOODHOUSE. 



Firft. Of the Effetls produced by the Germination of Seeds in 

 atmofpherical Air. 



On the 3d of June, twelve feeds of zea maiz were planted Germination of 

 in earth, and confined over water in a glaft veflel, in feventy ^ ds . ln ? tm °- 

 ounce meafures of atmofpherical air of the purity of 100, and 

 often expofed to the light of the fun. On the 1 2th, the corn 

 had vegetated, and was from two to five inches high. The 

 air being examined at this time, by throwing up one meafure 

 of it, over lime water, in an eudiometer, gave -j^ parts of car- 

 bonic acid air. Another meafure, after being freed from the 

 fixed air, and mixed with an equal meafure of nitrous air, pro- 

 duced an abforption of T 3 - ^~. On the 19th, the corn having 

 grown confiderably, and the air being tried again, no carbonic 

 acid gas appeared, and the purity was the fame as at firft. On 

 the 23d, the plants died, and the airs were found to confift of 

 y-l-g fixed, and T ^ azotic gas. 



Similar experiments were made with the feeds of apium pe- 

 trofelinum, Iacluca fativa, cucurbita citrullus, phafeolus fativus, 

 fifymbrium, and raphanus fativus, and with the fame refult. 



The atmofpherical air, in thefe experiments, appears to be The air loft oxi- 

 reducedin purity, by its oxigen uniting to the coal of the coty- gen b jJ unitln g 

 ledons of the feed, or to that of fome animal or vegetable mat- wards it became 

 ter contained in the earth in which the feeds are planted, or to mor epurej ani 

 that of fome decayed portion of the living leaves. was tota ]jy a b_ 



Ingenhouz, Humbold, and Thomibn, have obferved, that for bed. 

 foils have the property of abforbing oxigen; but as it cannot mould on 

 tje proved that any pure earth, or mixture of earths, render at- air moft probably 

 mofpherical air impure, it is certainly more philofophical to trom lts cai ou * 

 afcribe the impuriLy of the air to the formation of the carbonic 

 acid, the bafe of which generally exifts in all foils, 



II. Of 



