7. CONCLUSIONS. The conclusions drawn in the comparison of mill products from unstripped cane with diffusion products from stripped cane may be summed up as follows: A. The quantity of sugar expressed from unstripped cane by milling must be increased by eighty-four per cent. in order to equal that secured by diffusing stripped cane. B. The sugar must be increased by nearly eighteen per cent, and the purity must be improved by nearly eight degrees before mill juice from unstripped cane can equal diffusion juice from stripped cane. The diffusion juices also excel both in color and taste. II. COMPARE DIFFUSION PRODUCTS FROM STRIPPED AND UNSTRIPPED CANE. In the comparison of diffusion products from stripped and unstripped cane, following points have been particularly noted: the 1. The volume of water to be evaporated in order to secure a definite weight of sugar. 2. The color, purity and taste of the products. For comparison with the preceding diffusion trial a quantity of topped but unstripped sorghum was selected which analyzed 8.08 per cent. of sugar, equivalent to 10.65 per cent. if calculated upon a carefully stripped basis. This cane was cut, crushed, mixed and sub-sampled in the manner already described. In the diffusers it was also treated in the customary manner as far as temperature and time of digestion were concerned; the relative amount of water used, however, was very much increased. Stripped sorghum is comparatively dense, a cubic foot weighing thirty-seven pounds; unstripped sorghum is bulky, one cubic foot weighing approximately only twenty one pounds. A diffuser of seventy-two cubic feet capacity would, therefore, hold twenty six hundred pounds of stripped cane and nineteen hundred pounds of water. The same diffuser, however, would hold only fifteen hundred pounds of unstripped cane and three thousand pounds of water. In the following trial therefore two pounds of water were used for each pound of unstripped cane. For convenience of comparison the results obtained by diffusing stripped sorghum are here reprinted. A description of the details of this experiment may be found upon a preceding page. THE VOLUME OF WATER TO BE EVAPORATED IN ORDER TO SECURE A DEFINITE WEIGHT OF SUGAR. The following calculations are based partly upon facts stated in the above table, and partly upon analyses showing that a ton of unstripped and untopped sorghum contains one hundred and forty five pounds of sugar, of which ninety per cent. or one hundred and thirty pounds can be secured by diffusion. 1. The solution from the ninth diffuser working upon unstripped cane, analyzed 7.85 per cent. It would require 1,769 pounds of such a solution to contain one hundred and thirty pounds of sugar. 2 The solution from the ninth diffuser working upon stripped cane, analyzed 10.87 per cent. It would require 1,195 pounds of such a solution to contain one hundred and thirty pounds of sugar. In order then to obtain a definite weight of sugar, it follows, that if cane is stripped before it is diffused a saving of nearly thirty three per cent. will be effected in the weight of water to be evaporated. On one hundred and sixty tons of cane, an ordinary day's work at Rio Grande, this saving would amount to nearly 11,000 gallons. 4. THE PURITY, TASTE AND COLOR OF DIFFUSION PRODUCTS FROM UNSTRIPPED CANE. The most serious objection to unstripped cane lies in the effect of leaves and leaf sheaths upon the purity, taste and color of diffusion products. PURITY. In determining the purity of a solution, its percentage of sugar is divided by its specific gravity, expressed by the Brix hydrometer. The term is therefore used to represent the weight of sugar relative to that of other matter held in solution. When the purity is stated to be 60, it signifies that out of every one hundred pounds of material dissolved in water, sixty pounds are sugar. In cultivating, harvesting, milling and all subsequent manipulations, the aim should be to increase the purity of the cane juice; for the higher the purity the larger will be the yield of crystallized sugar. By referring to the table it is evident, for both mill and diffusion products, that the juice from stripped cane is much purer than that from unstripped cane. It is also evident, in case of the unstripped cane, that the mill juice is superior to diffusion juice, from cell No. 9; also that cell No. 9 contains the most impure juice in the battery. In case of stripped cane, however, the diffusion juice from cell No. 9 is five degrees purer than the mill juice; the average purity of the juice in the last five cells is also higher than that in the first five. These differences in quality between products from stripped and unstripped cane are due to the leaves and leaf sheaths alone. Direct experiments both by milling and by diffusion sustain this opinion. The leaves used were moistened before they were ground. Diffusion products came from cell No. 6. PURITY OF MILL AND DIFFUSION PRODUCTS FROM LEAVES AND LEAF SHEATHS. Out of every one hundred pounds of solids, separated from leaves, &c., by diffusion, there are eighty-six pounds of worse than worthless matter and fourteen pounds only of sugar. This fact offers a reasonable explanation for the low yields of crystallized sugar and the relatively high yield of syrup, common in the sorghum industry. There seems to be but one rational way of avoiding this trouble, that is to construct a stripping machine; for all of this injurious matter can be kept out of the sugar house, but cannot be readily removed if allowed to go into solutions. COLOR AND TASTE OF DIFFUSION PRODUCTS FROM UNSTRIPPED CANE. It has been already stated that in color, taste and acidity, diffusion juices from stripped cane equal mill juice from stripped cane. In comparison diffusion juice from unstripped cane was dark colored, bitter and decidedly acid. The diffusion juice from the leaves and leaf sheaths was very dark even when it was drawn from the first diffuser. This color deepened rapidly as the juice grew more concentrated; the bitter taste also became intense. A portion of this juice was allowed to stand over night, and the next morning putrefaction was evident. The fact that juice of low purity gives very poor yields of crystallized sugar and relatively high yields of syrup has been already noted. Sales of syrup are based almost exclusively upon color and taste, a few shades either way having greater influ ence upon the market price than noticeable variations in percentages of sugar. From a financial standpoint, therefore, the effect of leaves upon the color and taste of syrups is of extreme importance. This effect has been seen upon a large scale at Rio Grande. During this past season, as already stated, the diffusion battery was operated for twenty-six days upon mill bagasse from unstripped cane; this was done partly to avoid waste of sugar, and partly to test the apparatus and train the workmen. The juice was skillfully handled and clarified, but, owing to the color and taste due to leaves, the two hundred and twenty-nine barrels of heavy syrup secured are not worth more than one half as much as an equal quantity of the standard syrup made at this house from mill juice. CONCLUSION. The comparison of diffusion products from stripped and unstripped cane indicates that the financial success of the sorghum sugar industry now depends largely upon the removal of leaves and leaf sheaths. 1. Because their presence in the diffusers increases the amount of water to be evaporated by thirty-three per cent. 2. Because they impart to diffusion juices a very dark color and intensely bitter taste, the effect of which is to reduce the market value of syrups at least one-half. IV. SUMMARY. When the above conclusions, drawn under the heading II. and III., are studied in connection with the approximately correct reports of expenses and sales, under present working processes, the following general statements seem warrantable: 1. If carefully stripped cane only is used at Rio Grande, the substitution of diffusion for milling will be followed by financial success. 2. If unstripped cane is diffused, financial success will still be problematic: 1. Because of evaporation expenses; 2. Because of a serious depreciation in the market value of syrups, due to their inferior taste and color. NEW BRUNSWICK, N. J., December 21st, 1885. GEO. H. COOK, Director. |