10 BULLETIN 399, U. S. DEPARTMENT OF AGEICULTUEE. 
on evaporation, which may be taken as a partial measure of the 
freshness of the sample and also as a partial measure of the valuable 
constituents, varies to a considerable extent. This is to be expected, 
since the oils are prepared under such vridely varying conditions. 
In a commercial examination of sweet-orange oil. Schimmel & Co. 
have pla residue on evaporation at 2 to 4 per cent. 1 Often 
the residue on evaporation falls below 2 per cent, as in the sample 
of oil purchased in the open market. Rarely does it exceed 4 per 
cent, and when it does the conclusion may be drawn that the oil is 
either quite old or it is adulterated. Both the oils extracted by the 
methods outlined in this bulletin fall within the limits fixed by 
Schimmel & Co.. the oil obtained by pressure having the higl 
oration residue. This high percentage is due to the larger 
quantities of the w id nonvolatile constituents which were 
seel out and probably indicates a better grade of oil. 
The quantity of oil absorbed by the sodimn-bisulphite solution is 
of special hit ere- Ithough the tabulated results do not represent 
the true percentage of aldehydes present in these oil do serve 
as a comparative estimate of the commercial value. Of the three 
samples of oil, that which was obtained by heavy pressure is by 
far the best. The hand-pressed oil ranks second and the vacuum- 
distilled oil third. The last two. however, agree closely in the per- 
age of oil absorbed. 
The results of the comparison of the various oils indicate that the 
oils prepared by the methods described in this bulletin are equ 
not superior, to the hand-pressed oil obtained 'he three 
samples the one obtained by heavy pressure is the best. 
COM3IERCIAL POSSIBILITIES. 
From the results of numerous experiment- vorable 
acceptance by the trade after an examination of the oil, it is recom- 
mended that only the pressed oil be produce 
in money for equipment is small, and the product is of an extremely 
high grade. In addition to the peeling machine, the appar. 
and material required are as follows : 
Pre.-- _ Filter papers. 
Still (fig Tin containers. 
Separatory funnels. Unslaked lime. 
Glass or tin funnels. 
The pressing device as illustrated is of the simplest type. A r 
equally efficient and of more rapid manipulation can readily be con- 
structed by any mechanic. The drum should not exceed 12 inches 
inside diameter and should be about 16 inches high. It should be 
-oimel and Co. Semi- Annual Repor . 1906. p. 35. 
