Book format: An electronic version of a printed book that can be read on a computer or handheld device designed specifically for this purpose.
Publisher: RareBooksClub.com (14 May 2012)
By: J. H. Tucker (Author)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881 Excerpt: ...high: ±:.2 per cent. would better represent the average. The personal error does not necessarily affect the ultimate accuracy of the results, for each operator can set the scale of the instrument to suit his own eye: and if more than one use the same instrument, each can have his personal correction. Thus, if one operator reads the zero-point at--.4C and another at zero, the former will have to add.4 to all of his readings, f American Chemist, iv. 18-20. f Tollens (Ber. Deut. Chem. Oes., 1877, 1403) and Schmit-(ibid.. 1877, 1414) have proved that the sp. rotatory power of cane-sugar is not constant for solutions of all concentrations. The effect on the results of the optical estimation of cane-sugar is too small to be taken into account for technical work, being less than one-tenth of one per cent, in all instruments. Elaborate tables of the correction for the different instruments have been calculated, and may be found in the places cited, and also in Stammer's Lehrbuch der Zuckerfabrikation and Landolt's Optische Drehungsvermogen. OPTICALLY INACTIVE SUGAR. 173 ERROR OWING TO PRESENCE OF INVERT-SUGAR--OPTICAL INACTIVITY OF INVERT-SUGAR. All raw sugars and molasses from the cane contain invert-sugar, sometimes in large amounts. Inasmuch as the rotatory power of invert-sugar made by acting upon canesugar with acids, is strongly to the left, a mixture of the two will give in the saccharimeter a reading too low as expressing the cane-sugar. It has been considered that the invert-sugar in the products of the cane possesses the same rotatory power as that artificially prepared, and it was customary with some chemists to correct their polariscopic readings by adding to them T of the invert-sugar as found by the estimation with copper liquor. Recent researches...