OF FOREST-TREES. 



23 



lings by burying your seeds in dry sand, or pulverised earth, barrelling cHAP. 

 them, as I said, in tubs, or laid in heaps in some deep cellar, where the ^*^*y^ 

 rigour of the winter may least prejudice them ; and I have filled old 

 hampers, bee-hives, and boxes with them, and found the like advantage, 

 which is to have them ready for your Seminary, as before hath been 

 showed, and exceedingly prevent the season. There be also who affirm, 



" was in hopes that by the same means it might in time be so much more perfectly 

 " restored, that a candle would burn in it ; and for this purpose I kept plants growing in 

 " the jars which contained this air till the middle of August following, but did not take 

 " sufficient care to pull out all the old and rotten leaves. The plants, however, had grown, 

 " and looked so well upon the whole, that I had no doubt but that the air must constantly 

 "have been in a mending state; when I was exceedingly surprised to find, on the 24th of 

 " that month, that though the air in one of the jars had not grown worse, it was no better ; 

 " and that the air in the other jar was so much worse than it had been, that a mouse would 

 " have died in it in a few seconds. It also made no effervescence with nitrous air, as it 

 " had done before. Suspecting that the same plant might be capable of restoring putrid 

 " air to a certain degree only, or that plants might have a contrary tendency in some 

 " stages of their growth, I withdrew the old plant, and put a fresh one in its place ; and 

 " found that, after seven days, the air was restored to its former wholesome state. This 

 " fact I consider as a very remarkable one, and well deserving of a farther investigation, 

 " as it may throw more light upon the principles of vegetation. It is not, however, a 

 " single fact ; for I had several instances of the same kind in the preceding year ; but it 

 " seemed so very extraordinary, that air should grow worse by the continuance of the 

 " same treatment by which it had grown better, that, whenever I observed it, I concluded 

 " that I had not taken sufficient care to satisfy myself of its previous restoration. That 

 "plants are capable of perfectly restoring air injured by respiration, may, I think, be 

 " inferred with certainty from the perfect restoration, by this means, of air which had 

 "passed through my lungs, so that a candle would burn in it again, though it had 

 "extinguished flame before, and a part of the same original quantity of air still con- 

 "tinuedto do so. Of this, one instance occurred in the year 1771, a sprig of mint having 

 "grown in ajar of this kind of air, from the 25th of July to the 17th of August following; 

 " and another trial I made, with the same success, the 7th of July, 1 772, the plant having 

 " grown in it from the 29th of June preceding. In this case also I found that the effect 

 " was not owing to any virtue in the leaves of mint ; for I kept them constantly changed 

 " in a quantity of this kind of air, for a considerable time, without making any sensible 

 "alteration in it. These proofs of a partial restoration of air by plants in a state of 

 " vegetation, though in a confined and unnatural situation, cannot but render it highly 

 " probable, that the injury which is continually done to the atmosphere by the respiration 

 " of such a number of animals, and the putrefaction of such masses of both vegetable and 

 " animal matter, is, in part at least, repaired by the vegetable creation. And, notwith- 

 " standing the prodigious mass of air that is corrupted daily by the above-mentioned 

 " causes ; yet, if we consider the immense profusion of vegetables upon the face of the 

 " earth, growing in places suited to their nature, and consequently at full liberty to exert 



