394 - I'HILOSOPHICAL TRANSACTIONS. - [aNNOI 6gy. 



in L, though it had at first the disadvantage to be much less than that in i, yet 

 being set in water with which earth was plentifuily mixed, and that in i only in 

 water, without any such additional earth, the former had considerably outgrown 

 the other, weighing at last ]45 grains more than it. In like manner, that in 

 K, though a great deal less when put in, than that in i, and also injured by 

 insects; yet being planted in water wherein earth was dissolved, while the 

 water in which i stood had none, it not only over-took, but considerably sur- 

 passed the otlier ; weighing at last 2Q grains more than that in 1, and yet had 

 not expended so much water as that by above 2400 grains. The plant in n, 

 though at tirst a great deal less than that in m, yet being set in the foul crass 

 water, that was left in the still, after that in which m was set was drawn off, at 

 last had gained in weight above double what that in the finer and thinner water 

 had. The proportion of the augment of that plant which throve most, was to 

 the fluid mass spent upon it, only as 1 to 46 : in others it was only as 1 to 

 60, or too, or 200; nay, in the cataputia, it was but as 1 to 714. The mint 

 in B took up 39 grains of water a day, one day with another ; which was much 

 more than the whole weight of the plant originally ; and yet with all this it 

 gained not one fourth of a grain a day in weight. Nay, that in h took up 

 253 grains a day of the fluid, which was neai twice as much as its original 

 weight, it weighing when first set in the water but 12/ grains. And after all, 

 the daily increase of the plant was no more than 2^-1- grains. 



6. Spring and rain water contain pretty near an equal charge of vegetable 

 matter : river water more than either of them. The plants in the glasses a, 

 B, c, were at first of much the same size and weight. At the end of the ex- 

 periment the mint in A had gained 15 grains out ot 2558 grains of spring- 

 water; that in b 17i grains, out of 3004 grains of rain-water; but that in c 

 had got 26 grains out of only 2493 grains of river-water. From these and 

 other trials I know that these proportions hold for the main : but doubtless the 

 water that falls in rain, at some times contains a greater share of terrestrial 

 matter, than that which falls at others. A more powerful and intense heat 

 must needs carry up a larger quantity of that matter along with the humid 

 vapours that form rain, than one more feeble and remiss ever possibly can. 

 The water of one spring may flow out with a higher charge of this matter 

 than that of another ; this depending partly on the quickness of the ebullition 

 of the water, and partly on the quantity of that matter latent in the strata 

 through which the fluid passes, and the greater or less laxity of those strata. 

 For the same reason, the water of one river may abound with it more than 

 that of another: nay the same river, when much agitated and in commotion, 

 must bear up more of it, than when it moves with less rapidity and violence. 



