The second method, adopted by Wood, in Sikkim, is much simpler :—The dry bark is crushed into small pieces—not powdered—and is put into casks, where it is macerated in the cold with very dilute hydrochloric acid ; the liquor is then run off into wooden vessels, and mixed with an excess of strong solution caustic soda; the precipitate formed is collected on calico filters, and well washed with water. The precipitate is then gently dried, and powdered, constituting the crude febrifuge, which requires purifying. This is performed by dissolving the product in dilute sulphuric acid, and adding a small quantity of a solution of sulphur in caustic soda. After 24 hours, the liquor is carefully filtered ; the filtrate is mixed with caustic soda, and the resulting precipitate is collected on calico, washed with a little water, dried, and powdered ; it is then ready for use.
The operation is conducted in casks, worked in sets of three. Each cask receives 1 maund (82 lb.) of dry bark, which will undergo four successive macerations of half a week's duration, the liquor being passed through the three casks in rotation. The liquor used for the 4th (last) maceration is acidulated water ; when drawn off, it forms the liquor for the 3rd cask ; thence it is conducted to the 2nd cask ; and finally to the 1st cask, containing new bark, whence it is run off for precipitation. When starting anew, each cask will contain dry bark, so that the system of rotation is not brought into full operation till after the first fortnight. The liquor for precipitation is run into tubs; the others are drawn into buckets, for transference to the respective casks. Acidulated water is made in a vat, by adding 1 gal. hydrochloric acid to 100 gal. water. The weight of acid used in the exhaustion is 61 per cent, of the weight of dry bark. The caustic soda solution consists of 1 part of the alkali dissolved in 3 parts of water ; it is stored in iron vessels. The quantity required for precipitation of the bark liquor is judged of by the curdy appearance assumed by the precipitate ; every 100 lb. of dry bark consume about 6s lb. of the alkali.
Filtration of the precipitate is commenced on the following day, when the liquor is transferred to the calico strainers, previously wetted. The first portions that run through are returned, until the passing liquor has a bright ruby colour ; it is then allowed to flow away by a drain. When all the liquor has drained off, water is passed through the precipitate, until it ceases to acquire a red tint. The alkaloids on the filter should then exhibit a uniform cream-colour. The precipitate is dried, reduced to fine powder, and stored in suitable bins.
During the drying of the precipitate, a slight reddish-brown colour is developed ; this is removed by the following process of purification :-14 gal. of water are mixed with 2 pints of sulphuric acid, and 20 lb. of the dry powder ; about 4. pint of solution of sulphur in caustic soda is stirred in, and the whole is left for 24 hours. It is then filtered through calico into a clean vessel, care being
taken to get the liquor perfectly bright ; about 6 gal. of water are used to wash the sediment left on the filters ; the clear filtrate is thoroughly mixed with soda solution, to precipitate the the precipitate is collected on calico, washed with a small quantity of water, drained, dried, and reduced to fine powder. Wooden vessels are not so suitable for this operation as are those of enamelled iron, or earthenware.
The bark used is exclusively dry succirubra, and care is taken to mix the root-, stem-, and branch-barks together, as nearly as possible in the proportions iu which they are yielded by the plantations. Green bark would not be available at all seasons ; and it has been found that the trifling cost of drying the bark is more than repaid by the better product.
The purified febrifuge is a fine white powder, which, however, acquires a slight buff tint by keeping. It never agglutinates, and is freely soluble in weak acids, such as lemon-juice, &c. The cost price of this febrifuge is estimated at ls. 9d. an oz. ; it is as efficient as quinine at 9s. an oz.
Distribution of the Cultivation.—The cultivation of cinchona, both in government gardens and by planters, though principally by the former, has been instituted in many parts of India. The chief plantations are those in Sikkim and the Nilgiri Hills. Tho coffee planters in the Wynaad have put out many red barks, but the results are not encouraging. A small estate above the Kohlr Glifit, in S. Cauara, has been. abandoned. In 1871, a plantation was commenced on the Mahendra mountain, in Ganjam. Similar attempts on the Nulla Mully Hills were rendered abortive by the hot weather. In Coorg, results are said not to justify maintenance of the plantation. The Travancore Govern ment opened an estate at Peermede, near Maryville, which has given good promise of success. In the Pulney Hills, planting has been tried in several places ; the trees thrive well, but their bark is not rich in alkaloids. Under very adverse conditions, trees put out in the Tinnivelly Hills have done remarkably well. The result of an experiment with red barks on the Shevaroy Hills is very favourable. In the Kangra Valley, despite every attention, the trees succumbed to frost. The same result was obtained after protracted experiments in mauy parts of the Thin and Kohistan of the N.-W. Provinces and Punjab. The IVIaliatleshwar Hills, in Bombay Presidency, presented favourable conditions of soil and situation ; but extreme climatic changes proved insurmountable obstacles. The Sit tang Division of British Burma has been found well adapted to cinchona cultiva Lion, though the trees do not attain great size. Success has also attended the experiments in the Kbasia Hills (Nuuklow), in Assam. Ono new variety of C. officinalis, with pubescent leaves, culti vated in India, yields a remarkably rich bark, containing 6 per cent, of quinine, and 5 per cent. of einehonidiue.