CANE SUGAR. 



Appendix the true Brix is 20-72 and the specific gravity at 17-5 compared 

 with water at 17'5 C. is 1 '08652 as obtained by interpolation from the Brix 

 table given in the Appendix ; at the same time the specific gravity at 28 C. 

 compared with water at 17-5 C. is that corresponding to 20 Brix or 1-08329 ; 

 if the spindle is graduated at 27-5 C. and at this temperature reads 20, the 

 true Brix is 20 and the specific gravity at 17-5 C. compared with water at the 

 same temperature is 1*08329 ; from the table of corrections a spindle graduated 

 at 17-5 C. in place of reading 20 Brix would read (20 -68) = 19-33 B. 

 and the specific gravity at 27-5 C. compared with water at 17*5 C. is then 

 1-08026. Nearly all chemists are agreed that readings should be taken at (or 

 referred to) 20 C. and compared with water at 4 C. as standard. In the 

 Appendix a Brix table on this basis is also given ; whilst grudging the space 

 occupied by the necessity of giving two tables, the present confusion of systems 

 makes it obligatory. Any Beaume table is purposely omitted as this irrational 

 scale can disappear none too soon. 



2. By Drying to Constant Weight. 

 This method described below gives 

 the true total solids and true water, 

 and should be used in all analyses 

 except when a rapid * test,' as in the 

 control of crystallization in motion 

 processes, is required. 



Sugar solutions on partial drying 

 form a viscous mass from which the 

 last parts of water are very slowly 



FIG. 261. 



expelled under atmospheric pressure, 

 and at the temperature of boiling 

 water. As elevation of the temperature leads to decomposition of the organic 

 matter, sugar solutions should be dried in vacuo, and at the same time as large 

 a surface as possible should be exposed ; this latter end is obtained by pouring 

 the sugar solution over some such material as clean dry sand, pumice stone, or 

 filter paper crimped into a wad. The routine of an analysis is as follows: Into 

 a flat dish of suitable size is placed a sufficient quantity of the absorbent 

 material and the dish and its contents dried to constant weight ; from 5 c.c. to 

 10 c.c. of the material under analysis is then run into the dish, which is then 

 weighed a second time ; the dish is then dried to constant weight. 



In actual sugar house work it will be found very convenient to prepare in 

 advance a large number of dishes containing sand, the sand being adjusted so 

 that all the dishes are of uniform weight, and these are kept ready for use in a 

 specially constructed dessicator of large size ; as recommended by Spencer the 

 lead capsules used as coverings for bottles are very convenient and cheap. The 

 vacuum oven, used by the writer, which is capable of construction with planta- 

 tion labour, is shown in Fig. 261. It consists of a piece of six-inch copper 



472 



