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It is perfectly possible, then, to distinguish a complex oil by the irregularities in the shape of the curve, and when several oils of widely varying properties are present in any mixture this method of analysis will show their presence.


This article has outlined a method of analysis by fractional distillation with steam, and has shown the results of the application of this method to four turpentines of different kinds.

In discussing the results three physical properties have been given emphasis-specific gravity, index of refraction, and temperature of


1450 2 4 6 8 1460 2 4 6

8 1470 2 4 6 8 1480 2 4 6 8 1490 2 4 6 8 1.50 INDEX OF REFRACTION -15 °C.

FIG. 16.-Percentage weight-index of refraction curve for a crude destructive-distillation turpentine.

distillation with steam. These three properties were chosen because they lend themselves to rapid determination and clear interpretation. The odor and color were also found to be of value in the final conclusions. The basis for the judgment of an oil has been the combined. interpretations from the various physical properties as indicated in the shape of the curves, and no one physical property has been assumed to be all-conclusive. The interpretations from the various physical properties have been seen, however, to harmonize very well.

Certain advantages of this method seem worthy of mention.

(1) By introducing the principle of dephlegmation the separation of the constituents is made much more complete.

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FIG. 17.-Percentage weight-steam temperature curve for a crude destructive-distillation turpentine.

(2) The graphical method of expressing the data gives a ready means of interpreting the results and comparing various turpentines. (3) The large amount of data obtained makes the results very reliable.

(4) The low temperature at which the distillation is carried out reduces the danger of alteration of the sample during the analysis.

(5) The distillation is similar to certain technical distilling processes which have been found to give excellent results in practice, and suggests the possible results of applying such methods to the refining of turpentines.


JAMES WILSON, Secretary.

WASHINGTON, D. C., May 8, 1908.

[Cir. 152]


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