14 
BULLETIN 1166, U. S. DEPARTMENT OF AGRICULTURE. 
Bromphenol bine. — To produce the acid color, 0.5 cubic centi- 
meter of N/10 hydrochloric acid solution; to produce the alkaline 
color, 1 drop of N/20 sodium hydroxid solution. 
Thymol blue (acid range). — To produce the full acid color, 2 
cubic centimeters of 1.25 per cent hydrochloric acid solution ; to pro- 
duce the color of the alkaline end of the range, 1 cubic centimeter of 
0.005 per cent (N/700) hydrochloric acid solution. 
The volume in all the tubes should be made up at once to 5 cubic 
centimeters. 
The specific-acidity 20 values accepted for the several drop-ratios 
are given in Table 6. These specific-acidity and pH values, while 
not exact, are close enough for the purposes of this investigation. 
Table 6. — Specific acidity and pE rallies for indicators used. 
Drop-ratio. 
Bromphenol blue. 
Thymol blue (acid 
range). 
Specific 
acidity. 1 
pH. 
Specific 
acidity. 1 
pH. 
1:7 
6,300 
4,000 
2,500 
1,600 
1,000 
630 
400 
3.2 
3.4 
3.6 
3.8 
4.0 
4.2 
4.4 
400,000 
250,000 
160, 000 
100,000 
63, 000 
40, 000 
25,000 
1.4 
2:6 
1.6 
3:5 
1.8 
4:4 
2.0 
5:3 
2.2 
6:2.. 
2.4 
7:1 
2.6 
1 In round numbers. 
The color standards are quite permanent, and if stoppered and 
kept in the dark the tubes may be used over a long period of time (13, 
p. 451). Keference articles (particularly 12 and 13) contain details 
on the use of indicators covering pH values from 1.2 to 9.8. All 
determinations were made at room temperature, about 25 °C. 
Hydrocyanic add. — The determinations of available hydrocyanic 
acid Avere made by the method used by Viehoever for the hydrolysis 
of linamarin and the subsequent determination of hydrocyanic acid 
(17). 21 Because of the evident absence of the enzyme emulsin (as 
shown by negative results when the samples were macerated with 
water alone), however, other determinations were made in which 
emulsin was added, to insure the hydrolysis of any amygdalin pres- 
ent. The estimation of hydrocyanic acid in the distillate was made 
by the Volhard method and by the method of Viehoever and Johns. 
RESULTS OF CHEMICAL EXAMINATION. 
Table 7 shows the chemical composition of the dried apple pomace 
analyzed and that of corn silage with which it was later compared in 
the feeding tests (p. 27). The slight difference between the ether 
extract and protein results for sample 37254 in the original con- 
dition and those for the same sample after the seeds had been re- 
moved indicates the presence of an appreciable quantity of fine seed 
20 Specific acidity is based on the hydrogen-ion concentration of pure neutral water* as 
unity, as defined by Wherry (18, 19). 
21 Miss Ruth G. 'Capen, in the pharmacognosy laboratory of the Bureau of Chemistry, 
made these determinations. 
