550 CHAPTER XXVII 



that it is desirable to make an analysis of cane, a large number of stalks 

 must be taken and the finally completed sub-sample must be representative 

 of the length of the canes. 



Division of the stalks into quarters by splitting longitudinally is easily 

 done with a sharp heavy knife. 



If cane is defined as the material delivered to the mill the accompanying 

 trash and dry leaves are therein included. In sampling, the proportion 

 of trash to clean cane should be determined and its analysis made 

 separately. 



In general, when the composition of the cane from a certain field is re- 

 quired it is better to isolate a car load on the carrier and to take samples 

 of the juice and bagasse rather than to attempt to obtain a sample from so 

 unsatisfactory a material. 



Preservation of Samples. The preservation of samples composited over 

 periods as long as twenty-four hours adds materially to the capacity of the 



355 



chemist, and provided the compositing is intelligently done does not detract 

 from the value of the control. Indeed a careful analysis of a twelve-hour 

 sample is of more value than twelve hourly analyses necessarily performed 

 in haste. 



The two antiseptics employed to prevent fermentation are mercuric 

 chloride and formaldehyde. Of the former 25 mgrms. and of the latter 

 i c.c. of a 40 per cent, solution per 100 c.c. of sample is used. 



The above quantity of mercuric chloride causes an increase of o 05 Brix, 

 which correction is applied to the readings of the instrument. 



In taking samples of juices it is advisable to duplicate the sample, using 

 one for the determination of solids and one for sugar. The writer uses 

 formaldehyde as the preservative of the first, diluted to nearly that specific 

 gravity which experience has shown the juice will be. Correction for the 

 presence of the preservative in the Brix determination is thus eliminated. 

 The sugar sample is preserved with dry lead acetate, used in such quantity 

 as is necessary to defecate the whole sample. It should be remembered 

 that the use of antiseptics does not give an excuse for the neglect of 

 cleanliness. 



