308
J . L. B E E S O X .
NOTES ON THE D E T E K M I S A T I O S
needed for the completion of the digestion \vas considerably lengthened. The Gunning niodificatioii of tlie Kjeltlahl digestion process was also tested but the foaming resulting froiii the eriip1o)meiit of the large quantities of potassiuiu sulphate rendered the use of this iiiotlificatioii impracticable. Uy the ciiipio>-iiieiit of either nicrcuric oxide or metallic mercury. lion.ever, the osidatioii is effected rapidly and completely ant1 the subsequent pi-ecipitatioii of the phosphoric acid is easily acconiplislietl.
NOTES ON T H E ESTIMATION OF CRUDE FIBER IN SUGAR CANE. 13s J . I,. I ~ I C E S O S . 1'1i.D..~ ' K O I
I < ~ I I S T KI ~, O~V, l S I . ' L S I S U O A K S C I I O O I , . CASS.
r!
T
2s.
rwj.
HBKE is no part of the analytical work connected with the
chemical control of cliff usion process sugar house so utisatisfactory as that of the estiiiiation of the so-called I ' crude fiber in the cane. or that portion of the stalk wliich is insoluble in water. Duplicate aii:il\-ses, iiinnipulated ivitli great care, show wide variations. The average of such variations for IOO saniples taken consecutivell- \vas 0. j 3 6 per cent. Since the pewenrage of fiber is used as a factor i i i calculating the percentage of sucrose on the weight of the cane it beconies highly desirable that either a better iiietliotl of fiber estiniatioii be (lei-ised, or a more accurate and quick method of estimating the percentage of the sucrose directly on tlie weight of the cane. After a systematic and tliorougli investigation of the subject I have coiiie to the conclusion that a 1.ery accurate iiiethod of fiber estimation for technical purposes is iiot feasible, on account of tlie wide variation ill fiber content in different parts of tlie cane stalk. Extractioz of the S o l i i 6 k l;'adics.fiorir thc
[email protected] study was first made of tlie extraction of the sugars arid otlier soluble bodies in the chips as follo\vs : T\veiity grains of chips taken from the coinminuter were placed in a beaker, aiid nine volumes of water of varying teniperatures added. T h e diffusates were polarized every fifteen minutes until tlie last two readings were the same. I '
OF CRUDE FIBER IN SUGAR CANE.
309
T h e water in the beakers was kept as nearly as possible at the temperature of the water when added. Results : At
z j o C., diffusion complete in
60' c., ( ' 75-8oc C.,
"
'I
'I '1
65 minutes. '(
'' 45-50 '' 30-35
''
After pouring off the diffusate as completely as possible the above process was repeated in order to see if there was any appreciable difference in the rate of diffusion for the second application of water, but there was none. From the polariscope readings of the completely diffused solutioris the percentage of extraction of sucrose was calculated for the first two applications of water, and found to be seventy-five to eighty-fire per cent. Assuiiiiiig eighty per cent. for the average of each application of mater, and twelve per cent. as the average aiiiourit of sucrose in the chips, after five complete diffusions of each sample there would remain in the chips only 0.0384 per cent. of sucrose, which is practically nil. Theoretically, ninety per cent. of the sucrose should be reiiioved for each complete diffusion. I n quite a number of cases the final diffusate was tested for sugars by iiieans of the (Y naphthol reaction, which invariably showed only a very low percentage of these bodies. T h e coagulation point of the water soluble albumiiioids by heat was ascertained by gradually raising tlie tciiiperature of the first diffusates till coagulation began, and found to be between 80 and goo C. It is therefore uniiecessary to begin the extraction by the addition of cold water, then warm water, etc., as is usually done. Since the diffusion is so much more rapid at high temperatures it is advantageous to begin by adding water at 75' C. for the first two diffusions, and boiling water for the last three, letting stand each tiiiie for thirty minutes. This can be safely done, as it will be seen, without fear of coagulating the albuiiiinoids. This method was followed througliout tlie season. Losses Z'JL ihc Pvcpavafioii of fhc s ~ ~ ? J l p ~ C S . - - ~preparing 11 saniples for the estimation of the fiber in different parts of the cane, a portion of a cane stalk cut at tlie internodes with a sharp knife was rapidly weighed, ten grams cut off from both ends into a tared beaker, arid tlie stalk reweighed, and was found to sus-
310
J. L. BEESON.
NOTES O N THE DETERXINATION
tain a greater loss than the ten granis cut off. repeated in four cases, giving similar results. Results : Xo.
I.
"
2.
"
3.
This process was
Difference in weight after cutting off ten grams, ('
1 '
,'
,,
:,
,,
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