22 BULLETIN 1166, U. S. DEPARTMENT OF AGRICULTURE. 
occupying a mean position at 60 to 62. On me other hand, the 
specific acidity values of the extracts lie within rather narrow 
limits, that for the corn silage extract being the lowest. The alco- 
holic extract of the dried beet pulp, very weak as to total acidity, 
shows a remarkably high hydrogen-ion concentration, indicating 
over 30 per cent ionization, while the aqueous extract has an in- 
dicated ionization of 7.5 per cent. 28 Solving for K in the ioniza- 
tion formula (p. 17), assuming the acid to be monobasic, yields 
approximately 5X10" 3 for the alcoholic extract and 3.9X10" 3 for 
the water extract, values higher than those given in Scudder's 
tables for any common organic acid except oxalic. This indicates 
the presence of a " strong " acid in dried beet pulp. 29 
From the feeder's standpoint, then, the available acid in the 
beet pulp " mash " was more nearly equal to that in the moistened 
pectin pulp than would appear from an ordinary acidity titration. 
*_ Examination of the dried pectin pulp for cyanogenetic substances 
gave negative results. A positive test was obtained on seeds separated 
from the unground sample, but the quantity of -hydrocyanic acid 
in the dried pulp as a whole would be negligible. Apple pectin 
pulp is subjected to thorough cooking in the process of producing 
pectin, sufficient not only to render it safe in the matter of cyanogene- 
sis, but to sterilize the product as well. 
FEEDING VALUE OF APPLE BY-PRODUCTS. 
APPLE POMACE. 
As early as 1888, Wolff (H<3) published data on the digestible 
nutrients contained in apple pomace. The list of materials for 
which he determined coefficients of digestibility, however, does not 
include apple pomace. Probably, therefore, the data he gives were 
secured by using the coefficients for some similar material, not by 
actual digestion experiments with apple pomace. The same is true 
for the data that he published in 1895. for which different coefficients 
were used. 
Thus Linasey, assisted by Holland and Smith, in 1903, probably 
was the first investigator to ascertain the percentage digestibility of 
nutrients in apple pomace (100, 101).. His digestion experiments, 
which extended over two seasons, included complete trials with six 
sheep (full-grown, grade Southdown wethers). During the same 
periods productivity tests, in which apple pomace was compared 
with corn silage, were conducted with dairy cows. From 15 to 30 
pounds of pomace were given daily to each cow. The pomace used 
was obtained fresh from a cider mill and was stored under cover. 
Juice gradually drained from the pile, but the material remained in 
128 It is not uncommon to find the total titrable acid in an SO per cent alcohol extract 
higher than in the corresponding water extract, but to find an acid more highly ionized 
in the alcohol than in water is surprising. 
29 The presence in sugar beets of several relatively " strong " organic acids, including 
malonic, aconitic, and 1-tartaric acids, lias been reported by Riimpler (126), Of these. 
malonic has the highest ionization, with a reported " Ka" of 1.63XK)- S . at 2.1° C. If it 
be assumed that the acidity of the beet pulp extracts is due to a dibasic acid, such as 
malonic, instead <>f a monobasic acid, the values for Ka would he halved, giving 2.5 and 
1.0 times 10" 3 for the alcoholic and aqueous extracts, respectively, values not greatly 
exceeding that for the Ka of malonic acid. The higher observed values might be 
accounted for by the effect exerted by other dissolved constituents, such as salts. 
