300 Manurial Properties of Clay from Gas- Works. 



impulse to searches after new substances or new combinations of 

 known ones which can compete with guano, and the result has 

 been an enormous increase in the manure list, without much real 

 addition to the available and economical fertilizers employed by 

 farmers. It is beside the mark to point out the reasons of this, 

 though it may save some disappointment in future, and perhaps 

 direct effort more usefully, if one principal cause of failure be 

 indicated. Most experimenters have laboured without fully 

 realizing the problem to be solved. " A substitute for guano " 

 has signified to them a manure iceif/ht for loeiglit equal to the 

 substance of which it was to take the place, and which could be 

 sold for half or two-thirds the price. If there were no other 

 absurdity, here is a violation of. a first principle in political 

 economy. If their new substances were equally efficient with the 

 one against which they competed, they would be worth the same 

 price to the farmer, he would be ready to pay the same price for 

 them, and the producers, as good men of business, would never 

 think of selling at any lower price than the competition of guano 

 compelled them. The real question was, " How can I add to the 

 acreable produce of Britain by the discovery of a manure which 

 shall be a positive addition to all known manures, producible 

 in such quantity as to be a national benefit, and at such a price 

 as to leave a good profit to the farmer who uses it?" This mode 

 of viewing the subject might have rendered men benefactors 

 to their country, who have now wasted energy in seeking what is 

 unattainable. 



The results communicated by this paper are derived from in- 

 vestigations carried on without regard to any subordinate view of 

 the problem to be solved. The question was considered in its 

 totality, and unknown or useless substances have been converted 

 to a known and beneficial use. Farmyard manure consists of the 

 remains of a present vegetation, part of which has been animalized 

 by passing through (perhaps forming part of) the bodies of 

 animals. This manure does not support the life and minister to 

 the growth of vegetables until it has been decomposed into new 

 compounds, and the conditions under which nature has intended 

 it to yield the substances fit for plant nutrition are all fulfilled 

 when the manure is buried in the earth. 



Guano is the excrement of birds, most of which probably feed 

 on fish, that is, vegetation altogether animalized by becoming 

 part of or passing through the bodies of animals. Tliis ministers 

 to growth Avhen it is mixed in proper quantity with the soil, and 

 not otherwise, for plants placed in guano die as certainly as when 

 placed in fire. Although this manure is so much more concen- 

 trated by animalization that it has a market value lifty-six times 



