The spiroylic acid may be separated from the natural oil by treating it with a concentrated solution of caustic potash at a temperature of 113 deg.  Fahr., when wood spirit is formed and evaporates, and the solution contains the spiroylate of potash, from which, when decomposed with sulphuric acid, the spiroylic acid separates and subsides in the fluid.

Spiroylic acid is also formed by the oxidation of spiroyligenic acid, and when saligenin, salicin, courmacin, or indigo, is heated with caustic potash.

* * * * *

ON THE APPLICATION OF ORGANIC CHEMISTRY TO PERFUMERY.

BY DR. A.W.  HOFMANN,

Professor to the Royal College of Chemistry, London.

Cahours’ excellent researches concerning the essential oil of Gaultheria procumbens (a North American plant of the natural order of the Ericinae of Jussieu), which admits of so many applications in perfumery,[I] have opened a new field in this branch of industry.  The introduction of this oil among compound ethers must necessarily direct the attention of perfumers[J] towards this important branch of compounds, the number of which is daily increasing by the labors of those who apply themselves to organic chemistry.  The striking similarity of the smell of these ethers to that of fruit had not escaped the observation of chemistry; however, it was reserved to practical men to discover by which choice and combinations it might be possible to imitate the scent of peculiar fruits to such a nicety, that makes it probable that the scent of the fruit is owing to a natural combination identical to that produced by art; so much so, as to enable the chemist to produce from fruits the said combinations, provided he could have at his disposal a sufficient quantity to operate upon.  The manufacture of artificial aromatic oils for the purpose of perfumery[K] is, of course, a recent branch of industry; nevertheless, it has already fallen into the hands of several distillers, who produce sufficient quantity to supply the trade; a fact, which has not escaped the observation of the Jury at the London Exhibition.  In visiting the stalls of English and French perfumers at the Crystal Palace, we found a great variety of these chemical perfumes, the applications of which were at the same time practically illustrated by confectionery flavored by them.  However, as most of the samples of the oils sent to the Exhibition were but small, I was prevented, in many cases, from making an accurate analysis of them.  The largest samples were those of a compound labelled “pear-oil,” which, by analysis, I discovered to be an alcoholic solution of pure acetate of amyloxide.  Not having sufficient quantity to purify it for combustion, I dissolved it with potash, by which free fusel-oil was separated, and determined the acetic acid in the form of a silver salt.

  0.3080 gram. of silver salt = 0.1997 gram. of silver.

The per centage of silver in acetate of silver is, according to