200 
Our Climate and our Wheat-Crops. 
of nitric acid in the drainage-waters were — " we might be se- 
riously impressed with the significance of the fact, were it not 
that we know that these waters are extreme instances, and that 
in all probability such a loss rarely if ever occurs in ordinary 
farming." And, he goes on to say that Mr. Paine, the drainage- 
water from whose soil had yielded so much nitric acid, was in 
the habit of using on his land large quantities of such substances 
as hair, horn shavings, woollen rags, &c., to which in all proba- 
bility this large quantity of nitric acid is to be referred. 
In our own experiments we had for many years found, especi- 
ally in the case of grain-crops, that, of the nitrogen supplied in 
manure, a large proportion remained unrecovered in the increase 
of produce. It was found that when a given amount of nitrogen 
was supplied year after year, and the same description of crop 
was grown for a series of years in succession, generally less than 
half as much as had been supplied was recovered in the increase 
of crop. It was further found that, if the application of the 
nitrogenous manure were discontinued, only a very small pro- 
portion of the missing amount of nitrogen would be recovered 
each year in the succeeding crops. 
At first we were disposed to consider that this loss of nitrogen 
of manure might, in part at least, be explained by reference to 
the vital actions of the plant itself, as it had been concluded 
by various experimenters that plants evolved nitrogen by their 
leaves during growth. But, reference to the brief history of the 
progress of knowledge on the subject given in our paper — " On 
the Growth of Barley for Twenty Years in Succession on the same 
Land " — (this 'Journal,' vol. ix., S.S., part 2, pp. 331 et seq?) will 
show that, in 1861, we had come to rely much more on accu- 
mulation within the soil, and on loss by drainage, to account 
for the missing amount of the nitrogen of manure ; and that, 
as more and more evidence on these points was forthcoming, 
we attributed more and more of importance to drainage as a 
source of loss. 
In the autumn of 1866, finding that Dr. Voelcker was de- 
sirous to investigate the question of land drainage, we gladly 
provided him with samples of the drainage-water from the 
differently manured plots in the experimental wheat-field, and 
also with full particulars of their history for the purposes of 
inquiry. The samples were collected at five different periods, 
and Dr. Voelcker gave a summary of the results of complete 
analyses of 65 samples of such drainage-waters of accurately 
known history, in a paper in the ' Journal of the Chemical 
Society of London ' in 1871 (vol. xxiv., p. 276); and he gave 
the results more in detail, and with more of reference to their 
agricultural bearings, in a paper " On the Composition of Waters 
