A handbook of sewage utilization / by Ulick Ralph Burke.

  • Burke, Ulick Ralph, 1845-1895.
Date:
1873
Catalogue details

Licence: Public Domain Mark

Credit: A handbook of sewage utilization / by Ulick Ralph Burke. Source: Wellcome Collection.

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    manures whose practical value has been proved by a thou- sand experiments. On this point Mr. Moule has the follow- ing :— From a very little consideration of the infinitesimal minuteness to which, before they can be absorbed into the sap vessel, the nutritious particles of any manure must of necessity be reduced, it will readily be perceived that the aggregate amount of such nutritious particles requisite for the healthy growth of a given plant or of a given crop must, in its actual and immediate application, be very small indeed. It may fairly, I think, be asked here, in immediate relation to the value of manures, has the analytical chemist ever calculated how small the needful supply for a healthy plant or a healthy crop may be? and when ammonia or silex or phosphate has by digestion and assimilation been reduced to that infinitesimal minuteness requisite for absorption into the radix does his science enable him to detect it ? It appears to us that the solution of the whole question lies in the consideration of the profound differences which may result from the different conditions in which any sub- stance may occur. The water, says Professor Lewes, which will allay our burning thirst, augments it when congealed into snow We know that a change in the condition will cause a change in the manifestation of a force, so that often what ordinarily takes place in the laboratory will not take place in the organism The physio- logical question is not ' What are the chemical constituents of nutritive substances ?' it is, ' What are the substances which will nourish the organism ?' — (Physiology of Common Life, i., 115.) A chemist might manufacture a substance which should be similar under analysis to roast beef, yet this chemical roast beef would not support life ; and the nourishment of plants is not of so entirely different a character from the nourish- ment of the body as to render the digestibility, so to
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