105 



many facts under one view. The cause of this effect of alka- 

 lies upon geine, is to be sought in that power which has been 

 denominated catalysis, and which French authors designate 

 as the action of presence ; that is, the mere presence of a 

 body influences the nature of a second body, so as wholly to 

 change its properties. It causes the elements of organic com- 

 pounds to enter into new arrangements, by which they pro- 

 duce a totally different substance. The catalytic body, the 

 present body, the changing body itself, suffers no change, 

 except, perhaps, in some cases of ferments, whose activity 

 depends upon their being in a state of decomposition, while 

 the changed body loses nothing of its substance. It often 

 gains oxygen and hydrogen, or the elements of water. For 

 example, starch is converted into sugar by oil of vitriol. 

 The acid suffers no change. It acts by catalysis, and converts 

 the starch to sugar, simply by the addition of water, or its 

 elements. So the peculiar principle found near the eye of 

 the potato, converts starch first into gum, called dextrine, 

 and then converts this into sugar of starch. So malt, by its 

 gluten, converts starch into sugar in the process of brewing 

 beer. But the effect of this action may not be confined to 

 organic compounds only. It has lately been extended, by 

 an acute German chemist, to all chemical changes ; and it 

 has been maintained that all chemical decomposition takes 

 place in obedience only to a third substance, acting by its 

 presence. Hence, this extension of the principle, will allow 

 the decomposition of the mineral elements of soil, to be 

 attributed to the catalytic action of the plant. 



138. Having considered the action of the organic and 

 inorganic elements of soil upon each other, it is seen, that 

 though great, this action would be but very little in centuries. 

 'J'he geine itself would be dissipated in air, were it not that, 

 by this provision, it is combined with the earthy part of the 

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