10 BULLETIlsr 399^ U. S. DEPAETMEN-T 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 widely varying conditions. 

 In a commercial examination of sweet-orange oil, Schimmel & Co. 

 have placed the residue on evaporation at 2 to 4 per cent.^ 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 highest 

 evaporation residue. This high percentage is due to the larger 

 quantities of the waxes and nonvolatile constituents which were 

 pressed out and probably indicates a better grade of oil. 



The quantity of oil absorbed by the sodium-bisulphite solution is 

 of special interest. Although the tabulated results do not represent, 

 the true percentage of aldehydes present in these oils, they 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- 

 distiUed oil third. The last two, however, agree closely m the per- 

 centage 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 equal, if 

 not superior, to the hand-pressed oil obtained abroad, and of the three 

 samples the one obtained by heavy pressure is the best. 



COMMERCIAL POSSIBILITIES. 



From the results of numerous experiments and from its favorable 

 acceptance by the trade after an exaraination of the oil, it is recom- 

 mended that only the pressed oil be produced. The necessary outlay 

 in money for equipment is small, and the product is of an extremely 

 high grade. In addition to the peeling machine, the apparatus 

 and material required are as follows : 



Pressing device (fig. 4). 

 Still (fig. 5). 

 Separatory funnels. 

 Glass or tin funnels. 



Filter papers. 

 Tin containers. 

 Unslaked lime. 



The pressing device as illustrated is of the simplest type. A press 

 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 



1 Scliimniel and Co. Semi- Annual Report, Get.-Nov., 1906, p. 35. 



