38 ODOROGRAPHIA. 
by stereoptene or by spermaceti. The crystals should form in 
brilliant plates and in aigrettes reflecting the prismatic colours, 
in all parts of the liquid. Spermaceti is precipitated in a solid 
mass, easily recognizable, besides which its melting-point is 50° C., 
as is that of most varieties of paraffin; the microscopic crystals 
of the last, although somewhat resembling those of stereoptene, 
are easily distinguishable by careful comparative examination. 
A test for the presence of the oils of rose-geranium, palma 
rosa, etc., is described by Ganswindt *:—“ On mixing a few drops 
of pure oil of rose with an equal bulk of sulphuric acid, the rose 
odour is not changed, but oils used for adulteration change their 
odour; or 5 drops of the oil are mixed in a dry test-tube with 
20 drops of pure concentrated sulphuric acid ; when the mixture 
is cool it is agitated with 20 grams of absolute alcohol, when a 
nearly clear solution should be obtained, which, heated to boiling 
and then allowed to cool, remains clear yellowish brown. In the 
presence of the oils of rose-geranium, etc., the alcoholic mixture 
is turbid, and on standing separates a deposit without becoming 
clear.” 
The above-mentioned test has been confirmed ten years later by 
Panajotow t, who mentions that the brownish-red fluid resulting 
from the mixture of equal parts of oil of rose and concentrated 
sulphuric acid dissolves completely in 95 per cent. alcohol to an 
almost colourless solution, while the similar product resulting 
from oil of geranium is rendered turbid by the addition of alcohol, 
and a yellow, fatty, flocculent mass separates. 
O. F. Miiller has recently observed that a number of resins, 
oils, and lacs yield colour reactions with fuchsin solution de- 
colorized by sulphurous acid, the so-called “Schiff’s reagent.” 
Applying this test, Panajotow found { that if two or three drops 
of “Indian geranium oil” be shaken in the cold with 2 ¢. c. of 
the reagent, it gives at first a blue-violet, and after two hours a 
beautiful blue coloration. Under the same conditions pure otto 
of rose only gives a red coloration after twenty-four hours, and 
hence the slightest admixture of geranium oil is recognizable, 
because the bluish coloration is always formed at once. 
This test is, however, condemned by certain distillers of otto of 
rose as perfectly inefficient and useless, by reason that the reaction 
* Am. Journ. Pharm. 1881, p. 250. 
+ Berichte d. Deutsch. chem. Ges. xxiv. p. 2700. } Loe. cit. 
