. Cane sugar; a textbook on the agriculture of the sugar cane, the manufacture of cane sugar, and the analysis of sugar-house products. Fig. 320 used for acid materials and is preferable on the grounds of smaller addition, metal tubes ma\ become bent, due to rough use, without thedamage being observed. The life of a glass tube is shorter than that of ametal tube, but fracture is only due to avoidable carelessness. Polarimeter tubes are supplied in lengths of cms., 5 cms., 10 cms.,20 cms., 22 cms. (for elimination of calculation in certain routine dilutions)40 cms. and 60 cms.
. Cane sugar; a textbook on the agriculture of the sugar cane, the manufacture of cane sugar, and the analysis of sugar-house products. Fig. 320 used for acid materials and is preferable on the grounds of smaller addition, metal tubes ma\ become bent, due to rough use, without thedamage being observed. The life of a glass tube is shorter than that of ametal tube, but fracture is only due to avoidable carelessness. Polarimeter tubes are supplied in lengths of cms., 5 cms., 10 cms.,20 cms., 22 cms. (for elimination of calculation in certain routine dilutions)40 cms. and 60 cms. The Laurent instruments are usually built to accom-modate, and are supplied with, a 50-cm. tube. The diameter of a tube should be larger than that of the diaphragmthrough which the pencil of light passes, so as to avoid depolarization due tointernal reflection, and the glare which accompanies a tube of smalleidiameter. Bates adopts g mm. as a convenient Fig. 321 Convenience in Observation.—A dark room, or cabinet enclosing theinstrument, with source of light located externally is usually advised. Inplace thereof the writer finds the use of a shield of the form shown in Fig. 322very effective to cut off extraneous light. Polarimeter Scale.—The scale of the polarimeter is usually mounted onthe moving wedge of the compensator. The vernier is stationary. Thescale is either made of some alloy as nickelin, the expansion of whicli is low,or of invar, the expansion of which is zero. In some patterns the scale is 488 CHAPTER XXIV made of glass, and in others it is engraved on the quartz wedge. The appear-ance of the scale is as in Fig. 323, where the reading is Control of the Scale.—Quartz plates, the exact value of which has beendetermined in sugar degrees, may be obtained from makers. These platesare standardized at 20° C. in Europe, and as they are equally affected byvariation of temperature with the quartz wedge, they will se
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectsugar, bookyear1921
