Investigation of the Scientific and Economic Relations of the Sorghum Sugar Industry: Being a Report Made in Response to a Request From the Hon. George B. Loring (1883)

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SORGHUM SUGAR INDUSTRY. 51 was no more than that usual with sugar-cane juice, for it is estimated that only about 80 per cent. of the cane sugar present in the tropical juices is recovered in the sugar and molasses, a little over 20 per cent. being lost in the manufacture. In Tire's Dictionary, Appletou's edition, 1865, vol. II, p. 758, the writer upon sugar says as follows: The average quantity of grained sugar obtained from cane juice in our colonial plantations* is probably not more than one-third of the quantity of crystalline sugar in the juice which they boil. 13.—EFFECT OF FERTILIZERS UPON THE PRODUCTION OF SUGAR IN SORGHUM. Many experiments have been made with a view to the determination of this question. A limited number of these being taken, conclusions apparently well established would follow from such limited examina- tion. The result, however, of all the experiments, including 34 analy- ses of the ash of juices from sorghum grown upon plats differently fertilized, leaves the matter wholly undecided. In the literature of sorghum respecting fertilizers very much may be found, as in that upon sugar cane and beets, which appears to be well established, at least it is with great confidence asserted; but it is very doubtful whether any conclusion as to the effect of one or another fer- tilizer upon a sugar-producing crop rests upon data involving over 34 analyses of ash, and, as has been said, even this number fails to prove anything as to the effect of various fertilizers upon sorghum. 14.—THE SO-CALLED GUM A PRODUCT OF MANUFACTURE. In the purging of sorghum and corn-stalk sugar, it happens very often that this operation is of unusual difficulty, owing to the presence of a •certain gummy substance, and this practical difficulty has been by some so magnified that the economical production of sugar from these two plants has been confidently declared impossible. In this experience in Washington, as well as that of many other ob- servers, this peculiar substance has been found often to be present in quantity so small as to offer little, if any, resistance to complete purg- ing in the ordinary centrifugal. It is a matter of very great practical importance to determine those conditions which prevent its being produced in the manufacture of the sirup, since in no case has its presence been detected in the freshly expressed juices of either sorghum or maize. It appears to be formed by transformation of other constituents of the juice in the process of sirup production. B.— FUTURE INVESTIGATION. Although much important work has been already accomplished, and results fully repaying the care and expense bestowed have been attained, there yet remains a vast amount of work demanding further investiga- tion. Even granting that the questions already settled may suffice to place this new industry upon a safe and profitable footing, it by no means follows that it may not be made more profitable. Under the careful supervision of science fi*om its earliest infancy, the beet-sugar industry has so advanced that to-day 38 per cent. of the world's supply of sugar is derived from this source—a plant poorer in sugar, more expensive in cultivation, and far more difficult and costly in the means required for the extraction of its sugar than sugar cane— and yet under this scientific supervision it stands practically the sole rival of the cane as a source of supply for sugar. * British possessions.

62 SORGHUM SUGAE INDUSTRY. Perfected processes and improved appliances have enabled the man- ufacturers to obtain practically all of the sugar present in the beet, either as sugar or molasses or spirits, while, on the other hand, it is estimated that fully one-third of all the sugar in the cane is burned up in the begasse upon the sugar plantation. The same methods, the same apparatus, the same waste which are in use and characterize our production of sugar from cane obtains iu its production from sorghum. Sixty per cent. of juice from an actual 90 per cent. is the maximum yield of our cane mills. This, then, remains a matter for future experiments and solution. The effect of fertilizers upon the growth of the sorghum and of maize and upon the composition of their several juices yet remains in a state of entire uncertainty.* • The variety of soil best adapted for the production of sugar in these plants is equally a matter of which we are in comparative ignorance. We have at present six varieties of sorghum which for centuries have been grown in Northern China, and thirteen varieties sent from Natal. It is well known that these countries are the sources whence we origi- nally obtained our varieties some thirty years ago. It would be a most interesting question to determine whether these seeds direct from China and South Africa would grow canes as rich in sugar as those already examined, or whether in our climate and soil this sugar-producing quality has been developed during the past thirty years in which they have been grown here. Should this latter prove to be the case, it would give us reason to hope that improvements equally great might possibly follow; or that by careful crossing or selection a variety could be secured surpassing as a sugar-producing plant any of the numerous varieties now known. The methods of defecation in the process of manufacture are com- pletely unsettled, and the greatest difference of opinion and practice prevails among cultivators and manufacturers. The use of lime or of some other alkaline agent, the removal of the sediment, and the treatment of both the scum and the precipitate de- mand further investigation. The same is true of the use of sulphurous acid or oxide, in solution or in vapor, which is open to many doubts in the minds of sugar-masters— doubts which may be empirical, but which careful research alone can dispel or confirm. It is worse than idle to dogmatize on matters of this description, but dogmas will prevail where sound evidence is wanting. There are chemical agents which may be tried in connection with sorghum sugar production of which as yet we have no recorded experi- ence and no laboratory guidance; for example, the action of sulphites and hyposulphites of the alkalies and of alkaline earths in place of sul- phur fumes or sulphurous acid. There is a wide range of experiment possible in the methods of clari- fication by other agents than those familiar at present. We are ignorant of the possibilities which may attend the attempt to reduce the sucrose to an insoluble lime salt which can be kept indefi- nitely and transported as flour. The extensive literature of the sugar industry, enriched during the "The results of Prof.Magnus Swenson, of Wisconsin, (Appendix, p. 146,) are the latest which have been communicated to this Committee (November, 1882) OH the use of fertilizers, and these appear to show the inefficiency of nitrogenous manures on the sugar production of sorghum. This is also the conclusion from the use of guano at the Rio Grande plantation, where it had a fair trial in 1882. The whole subject of fertilizers require more extended research on a systematic plan, with varied soils.

SORGHUM SUGAR INDUSTRY. 53 half century or more since the days of Napoleon I by the labors of the best technical chemists of Europe, is far from being exhausted in the search for data long slumbering in almost forgotten pages from which important suggestions may arise in aid of the sorghum industry. We must not rest until an economical and rapid method is discovered to save the loss of about 40 per cent. of the juice which is now wasted in the begasse. Such an invention would enrich the world equally in the tropics and all cane-growing countries as in the fields of sorghum. But such methods are perfected only as the fruit of research, and this must not be relaxed when we are possibly on the verge of success. The Committee have not taken up the fodder question in connection with this general discussion. It did not properly fall within the range of inquiry assigned to them by the Academy. But it is conspicuous that it is a subject of great moment germane to this investigation, inasmuch as it is closely related to the best use of u waste material," and yet more so if .we consider the surprising fecundity of the sorghum stubbles, whether it is grown for green fodder or for soiling. It will be found on consulting the records of the Department of Agriculture that a notable amount of good work has been done in this direction by the Chemical Division, and it is clearly desirable that it be made a subject of further inquiry. The spirit of scientific investigation which has led the Department of Agriculture through its chemical and agronomic researches to results of such importance towards developing a new industry of national value has been liberally fostered by the General Government, and to some ex- tent also by certain of the States. The fruits of this policy are already beginning to show themselves in the decided success which has attend- ed the production of sugar from sorghum on a commercial scale in the few cases in which the rules of good practice, evolved especially by the researches made at the laboratory of the Department of Agriculture, have been intelligently followed. Sufficiently full returns from the crop of 1882 have already come to hand to convince us that the Industry is probably destined to be a commercial success. The practicability of separating sugar from sorghum has been abun- dantly shown in a multitude of examples. But the Committee are of opinion that many important practical questions, yet unsettled—some of which have been indicated in this report—can be better solved by the means of research now to be found in public institutions, and more especially in the laboratories and experimental works of the Depart- ment of Agriculture than elsewhere; and that the sugar-producing in- dustry of the whole country, both that of the tropical cane in the South and the sorghum over a far wider area, will derive yet greater benefits from the continued investigations of the cliemist of this Department, to whose former work we are already so much indebted. B. SILLIMAN, M. D., &c., Professor of Chemistry, Yale College, Chairman. WM. H. BREWER, Ph. D., Norton Professor of Agriculture in Yale College. C. F. CHANDLER, Ph. D., Professor of Chemistry, Columbia College, New York. S.W.JOHNSON, Professor of Agricultural Chemistry, Yale College, Director of the Connecticut Agricultural Experiment Station. GIDEON E. MOORE, Ph. D., New York. J. LAWRENCE SMITH, M. D., Louisville, Ky.

III. APPENDED PAPERS. 55