for Twenty Years in succession on the same Land. 95 
tlon now comprises about 300 specimens. In a large proportion of 
these the nitrogen, and in some the carbon, has been determined. 
Some have been experimented upon at Rothanisted in other ways, 
and some at Munich by Baron Liebig's son, Hermann von Liebig, 
who requested to have samples for examination ; and the whole 
are carefully prepared and preserved, with a view to more com- 
plete investigation whenever time will permit. Reference will 
be made further on to some of the results that have been obtained. 
It is, then, not the chemical examination of soils on a systematic 
plan, and by methods carefully arranged and well adapted for 
the solution of specific questions, that we have regarded as unim- 
portant ; but it is the mere determination, in accordance with 
antiquated theoretical ideas, of the ultimate percentage compo- 
sition of a soil, without due regard to the condition in which the 
constituents exist, and by methods which do not give sufficiently 
accurate or comparative results, that we have considered of little 
value. In the meantime let us see whether the synthetic, as dis- 
tinguished from the analytic method of enquiry, will not give 
as important and conclusive evidence as to the conditions and 
requirements of growth of barley, as it has done in regard to 
other crops. 
General Description of the Manures employed. 
It has already been said that the selection of manures for the 
experiments on barley Avas, in many respects, the same as that 
adopted for those on wheat. In reference to this point it may be 
useful, by way of illustration, to show the probable average 
amounts of certain constituents in what may be taken as fairly 
corresponding crops of wheat and barley. For this purpose we 
will assume a produce per acre of — 
Wheat, 30 bushels, of 60 lbs. per bushel = 1800 lbs., and 
3000 lbs. straw, = 4800 lbs. total produce ; 
Barley, 40 bushels, of 52 lbs. per bushel = 2080 lbs., and 
2500 lbs. straw, = 4580 lbs. total produce ; 
which will contain, approximately, the following constituents : — 
In Corn. 
In Straw. 
In Total Produce. 
Wheat. 
lis. , 
32 
IG 
9-5 
1 
3- .5 
0-5 
Barley. 
■Wlieat. 
Barley. 
Wheat. 
Barley. 
Phosphoric acid 
lbs. 
33 
17 
11-5 
1-5 
4 
12 
lbs. 
13 
7 
2U-5 
9 
: 3 
90-5 
1I)S. 
12 
5 
18-5 
10-5 
2-5 
03 
lbs. 
45 
23 
30 
10 
(i-5 
100 
lbs. 
45 
22 
30 
12 
75 
