40 
BULLETIN 1036, U. S. DEPARTMENT OF AGRICULTURE. 
tar creosotes indicated by figures 18 to 20 must, therefore, be due 
either to the type of retort or to the temperature of coking. 
Figure 22 shows two coal-tar creosotes produced from tars from 
the same mixture of coal and operated under the same management, 
and as nearly as possible at the same temperature, although one tar 
was produced in an inclined retort and the other in a horizontal 
9 
/ 
\ 
/ 
i 
S 
• 
/ 
^rl 
\W 
1 / g^N^g^ 
; — — -^j* 8 ^ ! — I — | — 1 Yi r 
c. 
-1 
i 
^ 
\ 
u ° 
t 
/ 
/ 
^ 
\ 
/ 
\ 
/ 
\ / 
' 
/ 
i 
/ 
/ 
*■ 
1 
«■- 
/ 
- ' 
/ 
Y 
/ 
s 
— 1 — 
i — 
y 
N 
^ 
~7 
*4?Z 
^ZDt 
-r '-'it 
4 V44 V 
P/jA^I. 
MV T.C - 
J-ti m 
yit. 71 \, 
XJt j\ * 
iff /-1a\ 
Ji / ^ V 
uJ?7 A =£- 
^J 
fW 
■ 
B 
s 7 ^ "^"1 
TEMPERATURE -°C 
240 260 
C D 
Fig. 20.— Sulphonation residues of fractions of authentic coa'.-tar creosoves. 
A. Horizontal-retort tar creosotes. 
B. Inclined-retort tar creosotes. 
Dotted line — Vertical-retort tar creosote. 
C. Semet-Solvay tar creosotes. 
D. Ottotarcreosotes. 
Dotted line — Koppers tar creosotes. 
retort. Figure 23 shows two coal-tar creosotes obtained from the 
same mixture of coal at different by-product plants which were at 
the time producing coke in approximately the same length of time, 
but which employ different types of oven — the Otto-Hoffman and 
the Semet-Solvay. These figures show the effect of different types 
of retort when the other two variables are practically the same. It 
is noted that the results are nearly identical, or, at least, that there 
