72 ODOROGRAPHIA. 
vacuum under a pressure of 16 millim. Citral boils at 116° C., and 
under normal atmospheric pressure at 228° to 229° C. without 
decomposition, if quite pure. At 15° C. its sp. gr. is 0°899. 
Semmiler ascertained * that the aldehyde C,)H,,O, obtained by the 
oxidation of geraniol with chromic-acid mixture, is identical with 
citral. According to Poleck + the fluid constituent of otto of roses 
is an alcohol, C,)H,,O, which by oxidizing agents is converted into 
the aldehyde citral, obtainable from geraniol by similar treatment. 
Messrs. Schimmel have ascertained the presence of citral in the 
following essential oils :—Citrus limonum, Citrus limetta, Citrus 
Madurensis, Andropogon citratus, Eucalyptus Staigeriana, Back- 
hausia citriodora, Tetranthera citratus, and Xanthoxylum piperitum. 
The Lime is the Citrus limetta, which grows wild in many 
tropical countries, but does not flourish even so far north as the 
Azores. It is found wild and cultivated in Jamaica, Dominica, 
and Tahiti; but the most important plantations are those esta- 
blished on the island of Montserrat, considered the most beautiful 
of the Antilles, situated in 16° 45’ N. lat. and 61° W. long. This 
island is only about eight miles in length from north to south, by 
a breadth of five miles from east to west, and is composed of a 
small cluster of volcanic mountain-tops rising out of the Caribbean 
Sea to the height of 3000 feet. The high mountains, whose steep 
sides are covered with virgin forests, seem to protect Montserrat 
from the hurricanes which desolate the neighbouring islands ; and 
the forests ensure a rainfall when the other islands are parched 
with drought. The temperature of Montserrat is remarkably 
uniform, the thermometer at night seldom falling below 69°, or 
rising even at mid-day above 90° F., with an average of 78° to 80°. 
The average rainfall is 54 to 64 inches a year. 
The Lime is a thorny, bushy evergreen tree, with handsome 
dark green leaves. ‘The leaves are so fragrant that they are uni- 
versally used in the West Indies to perfume the water in the 
finger-glasses at dessert. The small white flowers resemble orange- 
blossoms, and their scent is equally delicious. The very extensive 
plantations are owned by an English Company, which was formed 
for the main purpose of extracting the juice from the fruit ; but a 
very fine essential‘oil is also obtained from the rinds of the fruit 
im the same way ‘as the kindred ottos of orange, lemon, and 
* Ber. Deutsch. chem. Ges. 1890, xxiii. p. 8556, and 1891, xxiv. p. 205. 
T Ibid. 1890, xxiii. p. 3554. 
