Led. V. of Plants, 
it. §. BUT how doth the Aer concur to the Greene/t of Plants 2 
J anfwer 5 Notas it is meerly either cold or dry, or moift, nor yet qua- 
tenus Aer 5 but asitisa mixed, and particularly, a Saline Body: that 
is, as there is a confiderable quantity of Sulize Parts mixed with thofe 
which are properly <ereal. It being plain from manifold Experience ; 
That the feveral kinds of Salts,are the grand Agents in the Variation of 
Colours. So that, to fpeak ftrittly, although Sulphur be indeed the 
Female, or Materia fubfirata, of all Colours; yet Salt is the Mule or 
Prime Agent, by which the Sulphur is determined to the Produdion of 
one Colour, and not of another. 
12, §.  Ifthen it be the Aer mixed with the Fuyces of a Plant, and 
the Salt of the Aer, that makes it Gyeex 5 It may further be asked, what 
. kind of Salt? But this is more hard to judge of Yet it {eemeth,that 
it is not an Acid, but a Subalkaline Salt; or at leaft fome Salt which 
is different from a fimple Acid, and hath an Affinity with Alkalies. 
13. §. One reafon why I fo judge, is, Becaufe that although all 
Plants yield an Alkaly, or other Salt different from an Acid, and fome 
in good quantity; yet in moft Plants, the Predominant Principle is 
an Acid. So that the Supply of an Acid Principle from the Aer, for 
the Production of a Green Colour, as it would be fuperfluous 3 So alfo 
ineffectual : a different Principle being requifite to the ftriking of this, 
together with the Sulphur, into a Green Colour. 
14. §._ I fuppofe therefore, That not only Green, but all the Co- 
Tours of Plants, are a kind of Precipitate, refulting from the concur- 
rence of the Saline Parts of the Aer, with the Saline and sulpburions 
Parts of the Plavt; and that the Subalkaline, or other like Saline Part 
of the Aer, is concurrent with the Acid and Sulphurious Parts of Plants, 
for the Produéfion of their Verdures that is, as they ftrike altogether 
into.a Green Precipitate. Which alfo feemeth to be confirmed by di- 
vers Experiments hereafter mentioned, 
15. §. THE Colours of Flowers are various ; differing therein not 
only from the Leaf; but one from another. Yet all feem to depend 
upon the general Caw/és aforefaid. And therefore the Colours of Flowers, 
as well as of Leaves, to refult not folely from the Contents of the Plant, 
but from the concurrence likewife of the abient Aer. Hence it is, 
that as they gradually open,and are expofed to the Aer,they ftill either 
acquire, or change their Colour : no Flower having its proper Colour in 
the gud, (though it ke then perfectly formed) but only when it is 
expanded. So the Purple Flower of Stock-Fuly Flowers, while they 
are inthe Bud, are white, or pale. So Butchelors Buttons, Blew Bot- 
tle, Poppy, Red Daifies, and many others, though of divers Colours 
when blown, yet are all white in the Bud. And many Flowers do 
thus change their Colours thrice {ucceflively; asthe youngeft Buds of 
Ladys-Lookinglafs, Buglofs and the like, are all white, the larger Buds 
are purple or murrey, and the open Flowers, blew : according as they 
come ftill neerer, and are longer expofed, to the Aer. 
16. §. But if the Colour of the Flower dependeth on the ambient 
Aer 5 it may be asked: How it comes to pafs then, that this Colour is 
various, and not one, andthat one, a Greew? that isto fay that all 
Flowers are not Greew, as well as the Leaves ? In anfwer to this Three 
things are to be premifed. 
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