SOaiE OF THE ANIMALS FED AND SLAUGHTEEED AS HUMAN FOOD. 517 
degree of agreement in the percentages obtained by the three different methods 
referred to. 
In the fii’st of the three concluding columns (Table VL), headed “ By Addition," the 
figures there recorded are obtained by the addition of the percentages afforded by the 
separate items or parts, the details of which are given in Table V. The percentages so 
obtained, are, in fact, the result of duplicate nitrogen determinations made on each of four 
separate parts or mixed samples, for each animal. The next column, headed— “ By direct 
determinations on hair* or wool separately, and on a mixture of all other parts collect- 
Bely is obtained, as the description indicates, by duplicate determinations on two 
series of parts only. The last column, on the other hand, is obtained entirely by calcu- 
lation, as a check upon the percentages of nitrogen made by direct experimental deter- 
mination. The method of calculation is as follows From the percentage of the crude 
di-y substance, remaining after the removal of most of the fat by melting and expression, 
the fat afterwards extracted by ether is deducted. From the result so obtained, is 
next deducted the amount of the mineral matter. The remainder — the water, the fat, 
and the mineral matter, being thus all excluded — consists, of course, of nitrogenous 
. compounds of some kind or other. With the view of founding an estimate as to 
the probable amount of nitrogen contained in the mixed nitrogenous matter of entire 
animal bodies, upon a basis of something like specific and detailed facts, we have in 
vain endeavoured to find sufficient published data for estimating the probable relative 
proportions in the body of albumen, fibrin, {yuasi) gelatin, or chondrin, &c. In the 
absence of any appropriate data on this subject, we have assumed, of necessity some- 
what arbitrarily, 6-3 as probably the nearest round number applicable as a divisor 
of the crude nitrogenous substance of the animal bodies in question, to reduce it to 
nitrogen. This number, 6-3, supposes an average percentage of nitrogen in the mixed 
nitrogenous compounds, of 15-873. This is slightly higher than in either albumen or 
fibrin; considerably higher than in chondrin; but on the other hand, considerably 
lower than in gelatin*. It is probably, therefore, as good a figure as could be taken 
under the circumstances, as some confirmation of nitrogen determinations made upon 
such heterogeneous matters, and of the propriety of their application to the objects we 
have in view. 
If we are to assume, that the direct nitrogen determinations are nearer the truth than 
the calculated estimates, it would appear that the collective nitrogenous compounds of 
the whole body, in the cases in question, had a rather higher percentage of nitrogen 
than that represented by our number 6-3— namely, 15-873. For, although the discre- 
pancy in the percentages of nitrogen obtained by the different methods is invariably 
within the range of the second decimal place, the percentage indicated by the method 
of calculation merely, is in every instance somewhat lower than that by the direct expe- 
* M. Boussingavlt formerly adopted 15-0 per cent, of nitrogen (=6-666), in his calculations of nitro- 
genous vegetable compounds from the amounts of nitrogen ; but he has more recently adopted 16-0 per cent 
ot nitrogen (=6-25). •' x r • 
MDCCCLIX. D „ 
