he Berlin National Gallery), made him famous in Germany as
a representative of patriotic historical art. He also painted many
portraits of German princes and celebrated soldiers and statesmen. He
died at Dusseldorf on the 16th of June 1885.

CAMPHORS, organic chemical compounds, the alcohols and ketones of the
hydrocarbons known as terpenes, occurring associated with volatile oils
in many plants. They are extracted together with volatile oils by
distilling certain plants with steam, the volatile oils being
subsequently separated by fractional distillation. The term "camphor" is
generally applied to the solid products so obtained, and hence includes
the "stearoptenes," or solid portions of the volatile oils. They are
mostly white crystalline solids, possessing a characteristic odour; they
are sparingly soluble in water, but readily dissolve in alcohol and
ether. Chemically, the camphors may be divided into two main groups,
according to the nature of the corresponding hydrocarbon or terpene. In
this article only the camphors of commercial importance will be treated;
details as to the chemical structure, syntheses and relations will be
found in the article TERPENES.

_Menthol, mentha or peppermint camphor_, C10H19OH, 5-methyl-2-isopropyl
hexahydrophenol, an oxyhexahydrocymene, occurs in the volatile oils of
_Mentha piperita_ and _M. arvensis_ (var. _piperascens_ and _glabrata_),
from which it is obtained by cooling and subsequently pressing the
separated crystals; or by fractional distillation. It crystallizes in
prisms, having the odour and taste of peppermint; it melts at 42 deg.
and boils at 212 deg.. It is very slightly soluble in water, but readily
dissolves in alcohol and ether. It is optically active, being
laevo-rotatory. Menthol is used in medicine to relieve pain, as in
rheumatism, neuralgia, throat affections and toothache. It acts also as
a local anaesthetic, vascular stimulant and disinfectant.

_Thymol, thyme camphor_, C10H13OH, 3-methyl-6-isopropyl phenol, an
oxycymene, occurs in the volatile oil of Ajowan, _Carum ajowan_, garden
thyme, _Thymus vulgaris_, wild thyme, _T. Serpyllum_ and horse mint,
_Monarda punctata_. Thymol crystallizes in large colourless plates which
melt at 44 deg. and boil at 230 deg.. It has the odour of thyme, is
sparingly soluble in water, but very soluble in alcohol, ether and in
alkaline solutions. In medicine it is used as an antiseptic, being more
active than phenol. Iodin