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repeated experiments ; by putting up feeds into glafs j glaft a very elegant Ihew, flanding almoft exddly irl 



bottles, and lealing the botcles hermetically, and in rank and file through the leno-rh of the leaver 



fix months thofe feeds have loll their growing quality; Whence it may be thought^probable, that" the air. 



whereas part of the fame feeds which wcrc^ kept in freely enters plants, not only with the principal fund ' 



bags, grev/ at the age of two years; therefore it fliould of nouriflimcnt by the roots, but alfo throun-h the^ 



caution perfons not to exclude the air from their feeds, 

 if they intend they fliould grow. 

 Another inftance of the ufefulnefs of the air in vege- 

 tation, is the Sedum, which will pufli out roots with- 

 out earth and water, and live for feveral months: and 

 fome iorts of Aloes, if hung up in a room entirely 

 fecured fromi frods, will remain frelh for fome years, 

 though they will fenfibly lofe in their weight. 

 Air is capable of penetrating the porous and Ipongy 

 parts ot plants, and being there contrafted, and di- 

 latino; itfelf ao:ain. 



The air operates alfo within the bovv'els of the earth, 

 and by its fubtilty p^^fpiring through the pores, affifls 

 in the rarefadion of the crudities of the earth, and in 

 the difpelling all fuperfiuous moifture, entering i.ito 

 the very pores and veins of the trees, plants, herbs, 

 &c. carrying along with it thofe falts contained either 

 in itJclf, or lodged in the earth ; which falts or juices, 

 are altered according to the ievej-al figures or dimen- 

 fions of the different ftrainers or veilels of thofe feve- 

 ral plants, '"^---^ 



whi 



h grow upon the fame fpot of earth, 

 which is lb impregnated witli thefe falts : and thence 

 thofe^ varieties in tafte and fmeli proceed, notwith- 

 llanding they all receive their nourilhment from the 



fame ftock that is lodged in the earth. 

 The air alio affefts the branches, leaves, and flowers 

 of trees, plants, and herbs, entering and pcrfpiring 

 tlirough them, and even through the bark and body 

 of the tree ; and by the fame kind of fubrilty it does, 

 by its refrelhing breezes, moderate the intenfenefs of 

 the fun-beams, cooling, cliearing, blowing, opening 

 and extending all the offspring of nature, 

 l^he air fixes and infinuates Tts atrial fubflanc 



mto 



the liquid iap of vegetables : and as all the agitarions 

 in nature proceed from the contrariety of parts inha- 

 biting together, in this, aerial and liquid fubftances 

 being mixed, caufe this agitation and m.otion in ve- 

 getables, or, m.ore properly, fet it all into a ferment 

 (whether it be in the roots, or in the flem) ; and it 

 riles by co-operation of the fun (which is the tliird 

 agent m vegetation) up to the top of a tree, &c. as 

 liquids rife by fire to the top of the containing veffel. 

 This air, we find, produces a vibratory motion in fe- 

 veral bodies ; and particularly in plants, the air vef- 

 fcls thereof do the office of lungs : for the air con- 

 tained in them, fometimes contracfing, and fomedmes 

 expanding, according as the heat is increafed or di- 

 minifiied, preffes the veflels, and eafe them again by 

 turns ; and thus promotes a circulation of theii'juices, 

 which could fcarce be otherwife effefted. 

 Air, fays the learned Dr. Hales, is a fine elafi:ic fluid, 

 with particles of very different natures floating in it, 

 whereby it is admirably fitted by the great Author of 

 nature to be the breath or life of vegetables as well 

 as animals, without which they can no more live nor 

 thrive than animals can. 



As a, proof of the great quantities of air in vegetables, 

 he refers to the tliird chapter of his excellent treatife 

 of Vegetable Statics, wliere he fays, in the experi- 

 ments on Vines, the great quantity of air was viiible, 

 which^v/as continually afcending through the fap in 

 the tubes ; which manifellly fliews what plenty of it 

 is taken in by vegetables, and is perfpired otf with 



the iap through the leaves. 



He adds feveral experiments, as to an Apple branch. 

 Apricot branch, Birch, and other plants, to prove the 

 fame thina;. , 



And Dr. Grew has obferved, that the pores are fo 

 large in the trunks of fome plants, as in the better 

 fort of thick walking-canes, that they are vifible to 

 a good eye without a glais ; but v/ith a glafs, the cane 

 feems as if ftuck at top full of holes with great pins, 

 fo large as ^ ery well to refemble the pores of the fkin 

 m the ends of the fingers and ball of the hand. ■ 

 In the leaves of Pines, they are likewife through a 



furface of their trunks and leaves, efpecially at nio-hr, 

 wJien they are changed from a pcrfpiring, to a ilromrly 



imbibing ftate. 



Dr. Hales likev/ife tells us, that in all thofe experi- 

 ments that he tried to this purpofe, he found that the 

 a'.r entered very flowly at the bark of young fhoots 

 and branches, but mucli more freely throur^h old 

 bark j and that in different kinds of trees it htd dif- 

 ferent degrees of more or lefs free entrance. 

 And likewife, tfiat there is fome air both in ah elaflic 

 and unelaftic ftate, mixed witli the earth (which may 

 well enter the roots v/ith the nourifliment), he'found 

 by feveral experiments^ which he gives in the before- 

 mentioned treatife. 



_ ^ 



1>.e excellent Mr. Boyle, in making many experi- 

 ments on the air, among other difcoveries found, that 

 a good quantity of air was producible from vegetables. 



bypYitting Grapes, Plums, Goofberrics, Peafe, and 

 feveral, other forts 6f fruits and grains into exhaufted 

 and unexhaufted receivers, where they continued for 

 feveral days emitting great quantities uf air. 

 TJiis put the curious Dr. Hales upon farther re- 

 fearches to find out whatproportion of air he could ob- ' 

 tain out of the different vegetables, in w^hich it was 

 lodged and incorporated, which he performed by di- 

 vers chymio-flatical experiments, which he gives in 

 many inftances in his treatife of the analyfis of the air, 

 plainly fliewing in what manner he performed them, 

 and the events of them. 



That from half a cubic inch, or 135 grains of heart 

 ot Oak, frefh cut from a growing tree, there were 108 

 cubic inches of air generated, which is a quantity 

 equal to 2 1 6 times the bulk of the piece of Oak; that 

 tJie weight of it was above 30 grains, one quarter 

 part of the weight of 135 grains. 

 And he adds, that he took the like quantity of thin 

 fhavings from the fame piece of Oak, and dried them 

 at fome diftance from a gentle fire for 24 hours ; in 

 v/hich time they evaporated 44 grains of moifture'; 

 which 44 grains deducted frorri 135 grains, there re- 

 mains 91 grains for the folid part of the Oak: then 30 



jrains will be one third of the weight of the folid part 

 of the Oak. 



He gives another experiment of Indian Wheat, which 

 grew in his own garden, that he took 388 grains of 

 it when it was not come to its full m.aturity, and that 

 there were generated from it 270 cubic inches of airj 

 the weight of which air was 77 grains, viz. one fourth 

 of the weiglit of the Wheat. 



And again, that a cubic inch, or 318 grains of Peafe 

 generated 396 cubic inches of air, or 1 13 grains, i. e. 

 fomething more than one third of the weight of the 

 Peafe. 



And again, that from one ounce, or 437 grains of 



Mufl-ard feed, 270 cubic inches of air were generated, 



or 77 grains, which is more than one fixth part of the 

 ounce weight. 



He likewife adds, that there is a great plenty of air 

 incorporated into the fubftance of vegetables, which, 

 by the aftion of ferm.entation, is roufed into an elaftic 

 fcate, as is evident from thefe experiments following. 

 On the 2d day of March, he poured 42 cubic inches 

 of ale from the tun, which had been there fet to fer- 

 ment 34 hours before into a bolt head i and from that 

 time to the 9th of June, it generated 6^g cubic in- 

 ches of air, with a very unequal progreffion, more or 

 lefs, as the v/eatlier was warm, cool, or cold j and 

 fometimes, upon a change from warm to cool, it re- 

 forbed air, In all 72 cubic inches. 



March 



1 6th of April, 



12 cu- 



bic inches of Malaga Raifins, with 1 8 cubic inches of 

 water, generated 411 cubic inches of air; and then 

 again, it reforbed ^§ cubic inches in two or three cold 

 days. From the 21ft of April to the i6th of May, 

 it generated 78 cubic inches ; after wliich^ the 9th of 



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