14 | [AssEMBLY 
in darkness and near the surface of the soil, according to Koch, the 
process ceasing at about three feet depth. While we have carried 
out no examinations devoted particularly to this theory, yet our ex- 
amination of lysimeter water are in the direction of showing the 
changes in soil nitrogen in the form of ammonia or nitrates which 
occur from month to month and year to year. The nitrogen of the 
lower layers of the soil, as carried down by drainage, for it seems not 
to be found there, is recovered to the farm by deep-rooted plants, of 
which clover is the chief, and hence the growing of clover serves the 
double purpose of furnishing crop, and as well as an agency which 
works to save for us this nitrogen on the way toward waste. 
The lysimeter records afford matters of extreme interest, but it is 
preferable to await a longer record before discussing our results. 
The amount of rainfall and percolation, and the analysis of the 
monthly collections are put upon record in the chemist’s report. 
The amount of nitrogen is given in parts per million, thus avoiding 
the use of long decimals and as “parts per million ” are identical 
with “ milligrams per litre,” our results are at once comparable with 
records made on the continent of Europe where the French system 
of measures is in vogue. We may state here that one inch of 
water per acre weighs 225,965 lbs., and consequently ten parts per 
million of nitrogen or any other constituent of rain or drainage 
water corresponds to 2.26 lbs. per acre for each inch of rain or drain- 
age water. . 
In our feeding experiments we have endeavored to secure the 
utmost accuracy compatible with the circumstances. While is is 
impossible to work in this class of experiments without a quite large 
margin for error, a margin which does not admit of too slight differ- 
ences to count for much by themselves, yet we have preferred to 
offer the figures as recorded. The hygroscopic properties of fodder 
are such that analyses would show a certain variation in the water 
content not only in different days, but also in different periods of the 
same day, and the slight errors in the weighings of the food eaten 
are also a factor to be considered. In the long run these errors prob- 
ably balance each other, but as between any two results the differ- 
ences can only be used within a limit which is as yet undefined for 
the most part, but in live weight of cows may be accepted as from 
three to five per cent, as between two adjoining weighings. ‘It is from 
this point of view that the study of averages assumes importance, 
_ as by massing our results and averaging, these variations which we 
must call accidental tend to become divided and distributed in such 
a way as to counterbalance the plus and the minus changes. 
In our experiments with milk we have acquired results of true 
value. There is but one method which is safe to use for the deter- 
mining of the manufacturing properties of milk, and this is the 
manufacture. The churning of aliquot parts of milk under exactly 
duplicate conditions gives answer to the question of the value for 
butter making. Chemical analysis gives the food value of the milk, 
but does not determine the proportion of butter that can be made 
