186 OF MANURE. 



might completely replace one of the principal con- 

 stituents of the dung of the cow and horse, and 

 they contain also some phosphates. Indeed, they 

 are much esteemed in the Wetterau as manure for 

 meadows and moist land. 



It is of much importance to the agriculturist, that 

 he should not deceive himself respecting the causes 

 which give the peculiar action to the substances just 

 mentioned. It is known that they possess a very 

 favorable influence on vegetation ; and it is likewise 

 certain that the cause of this is their containing a 

 body,- which, independently of the influence which 

 it exerts by virtue of its form, porosity, and capabil- 

 ity of attracting and retaining moisture, also assists 

 in maintaining the vital processes in plants. If it 

 be treated as an unfathomable mystery, the nature 

 of this aid will never be known. 



In medicine, for many centuries, the mode of 

 action of all remedies was supposed to be concealed 

 by the mystic veil of Isis, but now these secrets 

 have been explained in a very simple manner. An 

 unpoetical hand has pointed out the cause of the 

 wonderful and apparently inexplicable healing vir- 

 tues of the springs in Savoy, by which the inhabi- 

 tants cured their goitre ; it was shown that they 

 contain small quantities of iodine. In burnt sponges 

 used for the same purpose, the same element was 

 also detected. The extraordinary eflicacy of Peru- 

 vian bark was found to depend on a small quantity 

 of a crystalline body existing in it, viz. quinine; and 

 the causes of the various effects of opium were 

 detected in as many different ingredients of that 

 drug. 



Calico-printers used for a long time the solid 

 excrements of the cow, in order to brighten and 

 fasten colors on cotton goods ; this material ap- 



ganese ; iron and magnesia occur in several of the peats analyzed. 

 Phosphoric acid also exists in them, both in its free state, and in com- 

 bination with lime and magnesia. In some peats Dr. J. found traces 

 of oxalic acid and oxalates. Ibid.y 210. See Appendix, for Peat 

 compost. 



