COEX OILS. 9 
vanized-iron can, in the center of which was a 1-inch glass tube ex- 
tending below a false bottom. The false bottom consisted of a 
screen of one-fourth-inch wire covered with several thicknesses of 
light, coarsely woven cloth. The material was packed on this false 
bottom and the benzol allowed to percolate through it into the bot- 
tom of the can, from which it was removed by means of the tube. 
The benzol used in all the extractions was a pure so-called water- 
white grade, which could be distilled completely on a steam bath 
at a temperature not exceeding 85° C. The first extract was reserved 
and a new batch of solvent added. The latter was allowed to pass 
twice through the material and then set aside. A new batch of 
solvent was added and allowed- to pass four times through the ma- 
terial. No further extraction was made, although the material still 
contained considerable oil, especially the wet-process germs. Table 
2 shows the quantity of oil present in the several materials before 
and after extraction. 
Table 2. — Percentage of oil in the wet-process and dry-process germs and in the 
oil cake before and after extraction with benzol. 
Percentage of oil 
present. 
Material. 
Germs: 
Wet process 
Dry process 
Oil cake: 
From wet-process germs. 
From dry-process germs. , 
The quantity of oil remaining in the material after the extraction 
with benzol, especially in the wet-process germs, was considerably 
greater than would be the case in commercial practice. 
REMOVAL OF THE SOLVENT. 
The last two benzol extracts obtained were mixed, and by heating 
the extract on a steam bath under partial vacuum approximately 90 
per cent of the benzol was removed. The residue of oil, together 
with the remaining benzol, was then added to the first extract, which 
contained the bulk of the oil removed from the material. From this 
mixture the benzol was distilled as thoroughly as possible in the way 
described. The last portions of the solvent were then removed by 
passing a current of dry steam into the mixture under reduced pres- 
sure. This treatment was continued until no more benzol collected 
in the receiver. The oil thus obtained still had a very slight benzol 
odor. If small quantities of water collected in the flask, this was 
removed from the oil by settling, with subsequent filtration if nec- 
essary. 
82276—22 2 
