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SORGHUM SUGAR INDUSTRY. 27 sugar plantation, during the pressure of the crop, the polariscope is nearly the sole dependence of the superintendent in judging many times daily how his juices are running. In 1879 this comparison was, between sorghum and sugar-cane, as fol- lows: ⢠Number of a nal Average au- c r o s e by volumetric analyses. Average su- crose by po- lariscope. . 22 Per cent. 13 26 Per cent. 13 15 Q i3 30 13 09 In 1881 the number of these comparisons was very greatly increased, being between 697 analyses of sorghum and 103 analyses of maize. Calling the value of the sucrose, as found by analysis, 100, the value indicated by the polariscope was 94.87 for the maize, and 95.96 for the sorghum. The nearly constant diff,erence.of about 4 per cent. less su- crose, as determined by these polariscope tests, than was found by cu- prous precipitation, was, for the time, attributed to a portion of invert sugar, and to various causes which probably were misconceptions, seeing that this discrepancy disappears almost entirely in the results of the present year, viz: Number of analyses and polarizations 517, of some forty varieties of sorghum. Total polarization, 5,440.76; average percentage, 10.524. Total by analysis, 5,433.72: average percentage, 10.510. 10.510: 10.524 ==100: 100.13. Each result of the 517 is of record, but the general result given suf- fices. The conclusion seems justified that any differences existing in the polarization and analyses with normal fresh juices are only differ- ences incidental to the work, and are not caused by any active rotatory substance present other than sucrose. If the juice is abnormal, very wide differences may exist. This was conspicuous in the mill work at the Department in 1881, both in juices and sirups. . SUMMARY. The facts relating to the economical production of crystallizable cane- sugar on a scale profitable to the farmer and manufacturer, from sor- ghum, in this country, so far as developed by the existing state of laboratory and field practice, appear to the Committee to be as follows, viz: 1st. That these plants develop at maturity, and when the seed is ripe, a maximum of cane sugar and a minimum of glucose.* 2d. That the maximum of cane-sugar in sorghum juices is found as- sociated with about one-tenth its weight of grape-sugar (glucose), and not far from one-fifth its weight of "solids not sugar," viz, ash, gum, chlorophyll, albumen, wax, aconitic acid, &c. 3d. That after maturity the relative amounts and proportions of the * Some of the widely discrepant statements by different observers may find, in part, ah explanation from the fact developed by the late investigation of Dr. Collier, that in sorghum the sucrose appears to fall off, or come to rest during the ripening of the seed, and then again after to increase. This interesting point has been fully devel- oped only by the work of the year 188-2, the full details of which will be found in the Annual Report of the Department of Agriculture for 1882.
28 SORGHUM SUGAR INDUSTRY. chief factors vary but little, even for a period of three months* or more, provided the season does not change; e. g., an early maturiug variety of sorghum holds its own until frost; a later variety has a shorter work- ing period. 4th. That while varieties of sorghum differ greatly in rapidity of growth and time of reaching maturity, in .size, weight, and consequent yield per acre, it appears that all varieties of sorghum resemble each other in developing at maturity, under the same conditions, nearly the same maximum percentages of cane-sugar, glucose, and solids, the cane- sugar maxima varying from 14 to 16 per cent. of the total weight of the expressed juice, the other factors being as stated under 2d.t 5th. The soil best adapted to the growth of a good crop of sorghum for sugar appears to be a sandy loam.J This plant thrives on soils and in climates too light and dry for maize, and makes the best "stand" when grown closer than Indian corn admits in a given locality. 6th. While good sirup may be produced from sorghum as a domestic industry and on a limited scale over a very wide range of country, the successful production of crystallized sugar on a commercial scale ap- pears to demand the skill and appliances of a sugar-house conducted in a systematic manner and with ample capital. 7th. The best results in sugar are obtained only when the ripe cane is manufactured on the same day (twenty-four hours) in which it is cut from the field. 8th. The seed of ripe sorghum is a valuable feed crop, comparable for fattening animals with maize, and in product is equal to from 2£ to 4 bushels per ton of cane. 9th. About 40 per cent. of the juice of sorghum is lost in the begasse, as it is to nearly the same extent in tropical sugar-cane, more than one- half of which loss may possibly be saved to the crop by processes under investigation. 10th. Of other residual products, the scum and sediment, rich in vari- ous elements of fertility, are now thrown away. (For the constituents of these waste products see the analyses at foot of page 29.) The begasse, when treated by a pulping machine, gives a valuable paper stock. Treated as a fertilizer, the begasse will return to the soil a portion of what the plant has borrowed from it in its growth. In regions where fuel is dear the begasse can be used with advantage as fuel. * A louger working period than three months has developed-itself by the experience n Texas upon the "Orange" variety. See letter of Colonel Richards of date Sep- tember 25, 1882, in the Appendix. tThis generalization appears fully justified by the work done at the Department of Agriculture and for the latitude of Washington; but it is yet an open question how far different sorts of sorghum may vary with climate and soil, two factors of commanding importance as yet imperfectly known. t For considerations of soil and climate, as well as fertilizers, reference may be had to the text, where these subjects are discussed, as well as to various statements in the Appendix.
