May 04, 2017 - Sale 2446

Sale 2446 - Lot 195

Price Realized: $ 625
?Final Price Realized includes Buyer’s Premium added to Hammer Price
Estimate: $ 500 - $ 750
"THE OPTICAL CHARACTERS OF THE VEGETABLE JUICES . . . I WILL ENDEAVOUR TO STATE" (SCIENTISTS.) WHEATSTONE, CHARLES. Autograph Letter Signed, "C. Wheatstone," to pharmacologist John Forbes Royale ("Dear Sir"), summarizing the results of an experiment published by [Jean-Baptiste] Biot concerning the optical properties of plant sugars in solution and their possible application to agriculture and manufacturing. 3 pages, 4to, written on a single folded sheet; short tears at ends of center vertical fold repaired with tissue, moderate scattered bleed-through, seal tear repaired with tissue and paper touching text on third page. (MRS) [London], 30 March 1836
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"You will find notices of Biot's investigations in vegetable physiology scattered through the volumes of 'L'Institut' for the last three years. The memoir referring particularly to the optical characters of the vegetable juices which yield either of the two kinds of sugars is published in the number of the 'Annales de Chemie' for Jan'y 1833. I will endeavour to state in the briefest manner possible the principal practical results, if you wish for more information you must refer to the original papers.
"If a homogenous ray of polarized light be made to pass through a determined length of certain liquid solutions, it is found to be affected in such a manner that on presenting an analyzing plate or reflector to it, its plane of polarization is altered. For some substances the deviation is to the right, in other to the left; and the magnitude of the deviation is proportionate to the density of the solution, and to the length of the path which the ray has to travel through the liquid. . . .
". . . The amount of the deviation indicates the quantity of sugar in the solution, and by this means it can be ascertained with great accuracy, by an immediate inspection, what are the relative proportions of sugar in different plants, in different parts of the same plant, and from the same plant at any period of its growth. The optical process is a thousand times easier than any chemical analysis. . . ."