84 MANURES. 



exist in plants — as sulphur in the cruciferous 

 family, particularly in mustard, copper in coffee, 

 wheat, and many other plants, iron in tobacco, 

 gold in the sage, &c., but these can only be 

 taken up by the roots as solutions of their 

 oxides, nothing solid being able to pass through 

 the spongioles. 



Some manures sensibly affect the colors of 

 flowers as is well known to the tulip growers, 

 even a moderate quantity of manure spoils all 

 their favorite stripes. The change of the pink 

 color of Hydrangea into purple is probably 

 produced by some manure containing excess 

 of alkali. 



The following statement of the strength of 

 manures on oats, rye, and barley, is extracted 

 by Decandolle from Hermstadt (Annalen der 

 Landwissenschaft, Annals of Agriculture.) 



Sheeps dung on, 

 Goats " 

 Horse « 

 Cow " 

 Human fasces 

 Pigeons " 

 Human urine, 

 Dry bullocks blood, 

 Vegetable earth, 

 Unmanured soil, 



These trials were under exactly equal cir- 

 cumstances^ but it would have been more 

 satisfactory had the experiment been tried un- 



