Darjeeling History Club

Continuation of Part 1 ………..

During the year 1906, there were three main cinchona plantations. First, the Rangjo valley block, consisting of the Rangbi and Mungpoo Divisions, which measured about 900 acres containing nearly over 2 million plants, of which more than a million and a half were Cinchona (Calisaya) Ledgeriana, nearly half a million of hybrid, and the remainder of Cinchona Succirubra. Second, the Rayeng valley block, consisting of the Sitong and Labdah Divisions, which together comprised an area of about 600 acres, with over 200,000 plants, more than half of which were Cinchona Succirubra and hybrid, and the remainder Cinchona (Calisaya) Ledgeriana. Third, the Rangpo valley block comprising of the Munsong Division.

L.S.S.O’Malley writes, “in appearance cinchona seed is small and chaff like, weighing 60,000 to 70,000 to an ounce. This is harvested during February and March, and at once sown in prepared beds, protected from the weather by thatched watertight lines, with sloping roofs constructed some 5 feet high in front and 2 feet high behind, and facing north to prevent sunshine drying up the seed beds. When half an inch high, the seedlings are replanted in other beds an inch apart, and later, when they have attained a height of 3 to 4 inches, they are again transplanted to other thatched nurseries similar to those prepared for seed beds, and near to the land to be planted out. By October the seedlings will have completed their first year’s growth and be a foot in height. The thatched covering of the lines is then removed and the seedlings hardened off by exposure to sun until February, March or April, when they are planted out in their permanent places in the land prepared for them. Once growing weather has set in, the young plantation for the first year is kept clear by hand-weeding about the plants and by sickling the intervening spaces. From the second year onward, weeds are kept down by repeated light hoeing and hand weeding. Barking operations are carried out equally throughout the whole year, and are first begun when the trees are three years of age. Thinning then becomes necessary wherever overcrowding exists, and individuals that show signs of unhealthiness are uprooted. Every year the whole plantation is thus gone over and trees removed where necessary. To collect bark, the trees are uprooted and divided into three parts – root, stem and branch. All the bark is completely scraped off with blunt knives, and the three kinds – root, stem and branch – dried in open air sheds, or in a heated go down during wet weather. Each kind is stored separately, and they are then taken for the extraction of the alkaloids to the quinine factory.”

The most extensively grown species was Cinchona Ledgeriana. Previously, a hybrid between Cinchona Succirubra and Cinchona Officinalis was grown largely, but it was replaced by another hybrid between Cinchona Succirubra and Cinchona Ledgeriana, which was raised at Mungpoo. From Mungpoo, selected trees yielding a minimum equal to 5 percent quinine sulphate were set aside for future plantations.

Regarding the preparation of cinchona febrifuge ( a medicine used to reduce fever ), L.S.S.O’Malley writes, “the dry cinchona bark is first mixed with slaked lime and ground to a fine powder. It is then moistened and tipped into vats containing dilute caustic soda solution, which is heated by a steam coil lining each vat and continually stirred by a mechanical arrangement. Oil is then run on to the homogeneous mixture, the stirring kept up for two hours, and afterwards the whole allowed to stand till the oil has again separated completely from the bark sludge, carrying with it most of the quinine in solution. The remainder of the quinine is extracted by repeating the stirring with a second quantity of oil. The oil layers are run off from the top of the exhausted bark, and in another vat are stirred with water and sulphuric acid, which extracts the quinine and leaves the oil ready to be used again on more bark. The excess of acid in the aqueous quinine solution is then neutralized, and the crude quinine sulphate separates out as a crystalline powder. It is purified from the other cinchona alkaloids by recrystallization from water, and from coloring matter by the aid of precipitants. The liquors from which quinine sulphate has been obtained are still saturated with it, and also contain all other alkaloids from the bark. They are mixed to give a product of definite composition, coloring matter is removed, and then all the alkaloids are precipitated together by addition of caustic soda. This mixture of alkaloids after washing, drying and powdering constitutes cinchona febrifuge.”

By,

S.K.Ghising

Terminologies

1. Hoeing : Thinning out or clearing out unwanted weeds.
2. Recrystallization : It is a technique used to purify chemicals. The purification is obtained by dissolving both impurities and a compound in an appropriate solvent. As a result of which, the desired impurities can be removed from the solution, leaving the other behind.

References

1. L.S.S.O’Malley, Bengal District Gazeteers Darjeeling
2. Image Source : File photo