From an estimate of the quantities of palm-sugar purchased for European refineries, added to the native refined sorts sold for export in the Calcutta market, under the names of gurp,Ita and dobarrah, Robinson concluded that 9500-10,000 tons, or at least I- of the whole annual quantity of sugar exported to England from India was in 1850 composed of palm-sugars. The attention bestowed by Europeans on the production of these sugars for the Calcutta or home markets, has been confined to the remanufacture or refining of the native raw material (khaur, dalloah, &c.) ; for this purpose, it is held in great esteem, producing a good-coloured and well-crystallized sugar, and yielding a greater percentage in weight of refined goods than can be obtained of equal quality from the same weight aud class of cane-sugars. On the other hand, raw palm-sugars are more liable to deteriorate by being kept in store, losing both colour and strength rapidly ; this applies, however, to the raw products only, the refilled or rebuiled sugars bearing transport and storage as well as those from cane.
The cause of these peculiarities appears to lie in the larger proportion of gluten present in palm sugars ; they are no less remarkable in the molasses than in the sugar itself, that from palm-eug,ar pussessiug far less saccharine matter, and being of much darker colour than that from cane, which is probably caused by the gluten being partly de-composed by the lime and heat of the boiling process. Another distinguishing feature is the absence from palm-sugar of the einpyreumatic oil observable in the cane product, and which gives to rum its well-known flavtur.
Considering the low cost of palm-sugars, and the little trouble and risk incurred in rearing the trees, it seems at first glance remarkable that European planters have not entered upon this culti vation for producing sugar on a large scale. But discouragements no doubt exiat in the nature of land-tenure in Bengal, the length of time the trees occupy in coming to full bearing, and the difficulty of collecting the juice for boiling into eugar by the European method after they have been reared. It has been shown that the annual produce of a full-grown plantation is equal to 78f maunds of goor per Bengal beegah, which, converted into hhaur, may be taken as equivalent to about 5i tons of muscovado sugar per acre.
and Maize-sugar.—The saccharine value of the grauainaceous plants known as N. China cane, Guinea corn, millet, durra, imphee, sorgo, &c. (chiefly Sorghum saccharatum, S. vulgare, and S. caff forum), has for ages been recognized in Africa and China ; and it would seem that sugar was extracted from maize (Zea Mays) by the ancient Mexicans. Of late years, new attention has been attracted to these plants as sugar-producers, principally in the United States, but also in Canada, Australasia, India, England, and France.
Qualities.—The cultivation of aorghum, maize, and pearl-millet, and the manufacture of sugar from their stalks. were made the subject of extensive experiments by the U. S. Department of Agriculture, during 1879, and again since. The investigations demonstrate little difference between the various kinds of sorghum as sugar-producers ; and seem to prove that each of them is, at a certain period, nearly as rich in sugar as the best sugar-cane. This maximum content of sugar is maintained too for a long period, and affords time to work up a large crop.
The varieties grown and investigated were Early Amber, White Liberian, Chinese, and Honduras sorghums, and pearl-millet. The analyses of each of the plants in successive stages showed that the uncryetallizable sugar diminishes as the true sugar increaees. They differ widely in the date when the mystallizable sugar is at its maximum, but are alike in that it is attained at about the same degree of development, viz. at full maturity, as indicated by the hard dry seed, and the appearance of offishoote from the tapper joints of the stalk. Analyses of several sorghums after they had been subjected to a. very hard frost, sufficient to form ice in. thick, and continued for 4 days, exhibited no diminution of crystallizable sugar, and no increase of uncrystallizable ; but the influence of the subsequent thaw was noticeable in the diminution of crystallizable and increase of uncrystallizable sugar. Thua it would appear that protzacted cold is not injurious to the quality of the canes, but that they should be worked up before they have thawed.
The Early Amber, Chinese, Liberian, and Honduras sorghums, and the pearl-millet, were planted on the same day, May 15, 1879. The relative weights of tbe different kinds of stalk are :— Early Amber, average of 40, 1.78 lb.; White Liberian, average of 38, 1.80 ; Chinese, average of 23, 2.00 ; Honduras, average of 16, 3.61.
These were grown side by side on land of equal fertility, and afford data for calculating the average yield of each per acre. Early Amber and Liberian closely correspond in their develop ment. While these two attain a sugar-yield equal to average eugar-cane by mid-August, the Chinese does not reach this condition until late September, and the Honduras not until mid October. An average of all the examinationa of the four sorghums during the periods when they were suitable for cutting gives the following results :—Early Amber, Aug. 13-Oct. 29 inclusive, 14.6 per cent. crystallizable sugar ; Liberian, Aug. 13-Oct. 29, 13.8 per cent. ; Chinese, Sept. 13 Oct. 29, 18.8 per cent. ; Honduraa, Oct. 14-29, 14-6 per emit.