Nutritive Values of different Crops. 
151 
We see then the vast use of such tables as those of Von Thaer 
ami Professor Johnston. If their data are not thought to be suffi- 
ciently ascertained^ should time be lost in verifying them ? It is 
in the power of any of us who will take the trouble of making the 
very simple experiment which Lord Spencer made, to learn, with 
something like certainty, the nutritive value of one or two of the 
crops proper to our own soil ; and this has been the chief object 
of the present paper. It was not intended to prove this or that 
probable or conjectural position; but, by drawing legitimate and 
important conclusions from such premises as we have, to illustrate, 
in as strong a point of view as possible, to practical men, who are 
sometimes too apt to undervalue an experiment, how simple 
the process, and yet how incalculably extensive the benefits, if 
each of us will but ascertain and record a fact. 
Painmick, March 8, 1843. 
XI. — Sanitary Effects of Land Draining. 
[From Mr. Ckadwick's Report to the Poor Law Commissionert.^ 
In considering the circumstances external to the residence 
which affect the sanitary condition of the population, the im- 
portance of a general land drainage is developed by the inquiries 
as to the causes of the prevalent diseases, to be of a magnitude of 
which no conception had been formed at the commencement of 
the investigation : its importance is manifested by the severe con- 
ciples of Liebig, who repudiate humic acid, by the alumina and other in- 
gredients of the soil which are known to have the power of absorbing and 
retaining it in large quantities, till required and taken up by the rootlets of 
the plants — a circumstance which may explain TuU's idea that tilth supplied 
the place of manure. If, on the other hand, the surface of the soil is left 
baked and hard, most of this ammonia (which, be it remembered, is equal 
in quantity per acre to that contained in 14 tons of farm-yard dung) is eva- 
porated, and carried off to the better tilled field of our neighbour. 
This natural supply of ammonia may not, however, be enough to restore 
the nitrogen abstracted from the land in vegetable and animal produce. 
Whatever that difference (and it would not be very difficult to get a good 
general estimate of its amount), it must of course be supplied by art. 
Whether the rain and carbonic acid of the atmosphere will supply all the 
rest of the elements required by the vegetable principles is at present matter 
of dispute, but it is agreed on all hands that they supply a very large por- 
tion of them. What they do not, must also be obtained by artificial means. 
With these exceptions, there is nothing else to be restored to the soil but its 
fixed ingredients. That they are comparatively small in quantity is perfectly 
ascertained. To estimate what that quantity is, even as regards all these 
ingredients severally, now that the analytical and arithmetical part of agri- 
cultural chemistry has made such rapid strides, is by no means beyond the 
reach of calculation.— W. H. H, 
