Father Ange also states that the substance is called in Persian Schakar tigal
, literally Sugar of nests; but his Arabic names, Schakar el ma-ascher
and Saccar el aschaar, apply to an entirely different substance, namely to a saccharine matter exuded, after the punctures of an insect, from the stems of Calotropis procera, R. Br.[I], of which plant he gives a quaint but tolerably characteristic description.
Mr. Loftus, who obtained the specimens which he presented to the British Museum, at Kirrind in Persia, in September, 1851, gives as the Persian name of the cocoons Shek roukeh—a term, probably, the same as the "C-hezoukek" (a misprint?) of Father Ange, but the signification of which I have not been able to discover.
Another notice of the same substance, with a figure, is briefly given in Dr. Honigberger's 'Thirty-five Years in the East' (Lond. 1852, vol. ii. pp. 305-6), where we read that Manna teeghul or Shukure teeghal, which are certain insect-nests of a hard texture, rough on the outside, smooth within, about half an inch in length, and of a whitish colour, are imported into Lahore from Hindostan.
M. Bourlier published in 1857 an interesting note on the same substance[J], which has been followed by M. Guibourt's communication to the Académie des Sciences, and still later by a memoir on the chemical history of Tréhala, by M. Marcellin Berthelot, also presented to the Academy[K].
From the investigations of M. Guibourt, it appears that the cocoons are composed of a large proportion of starch (identical with that found in the stem of the Echinops, upon which the insect forms its nest), of gum, a peculiar saccharine matter, a bitter principle, besides earthy and alkaline salts.
The saccharine principle, which has been especially examined by M. Berthelot, and named by him Tréhalose, is a body analogous to cane-sugar, but possessing distinctive properties, which separate it from that and all other varieties of sugar.