Page:On the Application of Sewage in Agriculture.djvu/5

( 5 ) diminishes, and its efficiency is then restored by the addition of wood-ashes rich in potash." These arguments would seem unanswerable as to the value of sewage, both in its solid and liquid portions. Its value per ton is a question for chemical professors, but I think the authority of Liebig, on a purely chemical question, is at least worthy of the respect of every one connected with chemical science, whatever they may think of his practical deductions in its application to agriculture. Another class of objectors will admit the value of sewage, but say that there is no way of collecting it, and therefore it must be allowed to run to waste. To say that there are mechanical difficulties in the way of anything in this practical age is almost an absurdity; for there is no work so gigantic that our engineers are not prepared to grapple with it. To say that the present arrangement is better, in a sanitary point of view, than one in which sewage should be collected, is certainly a mistake, as there can be no doubt that such a mode of effecting this object might be adopted as would be greatly superior to the present plan. The third objection which may be urged, is the only one which seems to me to have any weight; it is, that we have not the wish to change our present expensive and unwholesome system, because it would be repulsive to our feelings to adopt any mode of collecting substances which we regard with disgust. I fully sympathize with this view of the subject, but at the same time I do not see any reason why those who can gain profit by an honest calling should not be permitted to benefit themselves and society by the collection and sale of what is now most injurious, and might be made most advantageous to the interests of mankind. There is no reason why the solid portions of sewage might not be dried and compressed so as to form a marketable commodity like guano; and by the use of wood or peat-charcoal in its preparation, I have no doubt that it might be completely deodorized, and rendered in every way less disgusting than ordinary farm-yard manure. Under its use the land would continue undiminished in fertility, so long as the earth moved round the sun; inasmuch as everything is restored to the ground which has been taken from it, and the produce of the country would be doubled. I am aware that it will be objected to Liebig's estimate of the value of sewage, that although originally rich in the elements of vegetable growth and nutrition, the escape of gases through the gully-holes of the sewers, deprives it of its value, and the residue becomes hardly worth collecting. But this only shows that we have been at no trouble to preserve the above elements, and that we require to adopt some mechanical arrangement which shall prevent the escape of ammonia and other important constituents of manure. The Chinese adopt the plan of keeping it in close vessels, being indifferent to unpleasant odours; but I am far from wishing to see anything of the kind resorted to in this country, unless by means of wood or peat-charcoal complete deodorization can be effected. I do not, however, despair of seeing public "cabinets" established in every large town of the empire, which shall be so constructed as to substitute a stream of peat-charcoal (coarsely powdered to avoid dust) for the rush of water at present employed in our water-closets, which shall be as inodorous as