218 
On the Theoretical and Practical Value of 
and they were carried out at great expense, with a variety of 
feeding-stuffs which were given to oxen, sheep, and pigs, care 
being taken to put up a sufficient number of fattening animals ■ 
to eliminate the irregularities arising from the different feeding 
capabilities of individual animals. The food consumed was 
carefully analysed, the gain in the live-weight noted, and the 
loss in food by respiration ascertained ; and the amount and 
quality of the manure produced by the consumption of various 
foods were determined by laborious weighings and analyses. 
In illustration of this part of my subject, I may be permitted 
to quote the following tabulated results (p. 219), which are 
copied from one of Mr. Lawes's important and highly interesting 
published papers relating to experiments upon fattening beasts, 
sheep, and pigs. 
It will be noticed that the greater portion of the nitrogenous 
and mineral matters of the food is recovered in the manure, 
and that the greater part of the non-nitrogenous substances is 
lost by respiration and other exhalations, whilst a comparatively 
small proportion of the nitrogenous substance and of the mineral 
matter of food is retained in the increase. 
It will further be observed that for a given amount of increase 
produced, oxen void more as manure, and expend more in 
respiration, &c., than sheep ; and sheep very much more than 
pigs. And lastly, that for a given weight of dry substance con- 
sumed, oxen void more as manure than sheep, and sheep much 
more than pigs ; but oxen respire rather less than sheep, and 
sheep rather less than pigs. 
The proportions of certain constituents in a ton of various 
articles of food which are stored up in the animal, and the pro- 
portions which pass into the manure by the consumption of a 
ton of different kinds of food, have thus been ascertained with 
tolerable precision by actual experiments. If, therefore, the 
composition of the various kinds of food that are given to 
lattening-animals is known, we can determine beforehand, 
without actually analysing the manure produced from the con- 
sumption of a ton of each kind, how much nitrogen, potash, 
and phosphoric acid existing in the food will be recovered in the 
manure produced. And as nitrogen (or its equivalent expressed 
as ammonia), potash, and phosphoric acid (or its equivalent 
expressed as phosphate of lime), have a certain market-value 
as manuring constituents, we can likewise ascertain the money- 
value of the manure produced from the consumption of a ton 
of any of the ordinary stock foods, the average composition of 
which has been ascertained. 
By allowing %d. per lb. for ammonia, 2d. per lb. for potash, and 
