Torm Sewage. 
4G9 
ter, but relatively a small quantity, we can follow this procedure to 
advantage only with grass-crops. 
It may be said that liquid njanure has also been used with advantage 
on clay soils. To this I would reply that on clay soils, when Avell 
drained, pure water has been likewise used with very great advan- 
tage ; and that by irrigating clay soil with the purest water, even 
distilled water, we should probably obtain a very high produce. 
Indeed, experience shows that in our neighbourhood, where clay 
soils, — well-drained clay soils, abound, the spring produce is almost 
entirely regulated by the amount of rain that falls. A showery 
spring gives us more grass than any description of manure, be it 
natural or artificial, that we can put upon the land. When, there- 
fore, sewage produces on clay soils a highly beneficial effect, I think 
it is principally in virtue of the amount of water which it supplies. 
Mr. Mechi made a true observation when he said that in all 
calculations the water has been neglected. In many cases it is 
a most valuable constituent. In the case of clay soils which 
contain an abundance of fertilising materials, the water, when put 
on in large quantities, so as to soak completely a large mass of 
soil, renders these materials soluble, and bj^ degrees they are 
brought within reach of the growing plant. Thus it is that water, 
pure water, on clay soils produces in many cases enormously large 
results. In such cases the quantity of matter which we put on in 
sewage is too small to have any practical bearing on the result. 
Whilst, then, on clay soils water is the most valuable constituent 
of sewage, it is also of great utility on sandy soils, although, when 
we must furnish to the soil all the plant food required to produce 
a crop, even the fertilisers contained in sewage assume a very 
high importance. There are various other topics on which I 
must not touch, after having already detained you so long, but 
I trust that on several points which I have brought forward to-day I 
may have removed some misconceptions affecting that important 
question, the proper application of town sewage. 
The Discussion. 
Sir John Johnstone, M.P., observed that he, with some other gen- 
tlemen, had superintended a large lunatic asylum in the neighbour- 
hood of York, and had endeavoured to utilise its sewage in various 
ways. Not having grass-land sufficient to take it all, they had 
poured a part over the garden gi-ound cultivated by the patients, in the 
hope that what was valuable in it might remain in the soil. It was 
so applied during the winter, and the governor of the institution 
fancied he saw good results in the crops of roots, cabbages, and 
other market-garden produce ; but after what the learned professor 
had stated to-day it seemed to bo doubtful whether it might not as 
well be let run into the river. The soil was diluvial, and of a 
rather porous sandy nature. 
Mr, Frere said Dr. Voelcker had showed that the value of a fer- 
tiliser might be estimated by the crop that it enabled us to grow off 
the soil. Now it must be borne in mind that certain fertilii-.ers 
