152 
Liquid Manure. 
into the vegetable organism in a soluble state. I believe that the 
quantity of water which passes into the plant is amply sufficient 
to dissolve from the soil a sufficient quantity of the various mineral 
matters required to meet the wants of cultivated plants. In ac- 
counting, therefore, for the presence of potash, phosplioric acid, &c., 
in plants, it cannot be reasonably urged that soluble manuring 
matters, such as potash, phosphoric acid, &c., in contact witli 
soil, are rendered insoluble, and that therefore plants must take 
up their food in a solid state. It is true, that the most soluble, 
and, I may add, the most valuable substances, contained in 
iertilizing liquids are rendered coniparativehj insoluble in contact 
with most soils ; but I feel assured that it is impossible to render 
them perfectly insoluble. 
All good soils left in contact for a short time with pure rain- 
water yield a considerable quantity of potash, phosphoric acid, 
&c., to the water ; and water charged with carbonic acid dissolves 
a still larger proportion of these and other soil-constituents. 
Purely sandy soils alter (comparatively) but little the composition 
of liquid fertilisers which are passed through them ; clay soils, 
on the other hand, materially alter the chemical constitution of 
this liquid. If there is truth in the remarks I have made 
respecting the solubility of mineral food of plants, and the im- 
probability of plants taking up food in a solid form, we may 
expect that no soil, however stiff it may be, will completely 
remove all the ammonia, potash, phosphoric acid, &c., contained 
in dilute fertilizing liquids. On the other hand, if plants can 
take up solid food in some mysterious unexplained manner, it 
would not be surprising that clay soils rendered insoluble the 
whole of the ammonia, potash, &c., contained in a fertilizing 
liquid : for, supposing this to be the case, the plant might still 
grow luxuriantly. The changes which manuring liquids undergo 
in contact with soil, it will be perceived, have a much wider 
application than may appear at first sight ; they are, indeed, 
intimately connected with the theory of vegetable nutrition. I 
am happy, therefore, to be able to report a fifth experiment, 
which is of peculiar interest in this respect. The experiment 
was made with a soil from Tiptree Hall, kindly sent to me by 
Mr. Mechi. This soil, and the subsoil on which it rests, 
yielded, on mechanical analysis : — 
Subsoil. Surface-soil. 
Moisture 9-4(J 3-91 
Organic matter and water of comhination .. 4-87 4*80 
Sand • .. 9-2G 1097 
Lime 1-12 219 
Clay 75-29 78 13 
100-00 100-00 
