. On microscopical manipulation : being the subject matter of a course of lectures delivered before the Quekett Microscopical Club, January-April, 1869. s only the undulations in oneplane to pass, the other being stopped. The cause ofthis action is, as yet, not understood. If two plates oftourmaline are superposed, and held before a stronglight, it will be found that the light is alternatelytransmitted and stopped at every go°, when one ofthe plates is rotated. The same effec^t is produced, in a much greaterdegree, by using a pair of crystals of sulphate of iodo-quinine, more commonly known as
. On microscopical manipulation : being the subject matter of a course of lectures delivered before the Quekett Microscopical Club, January-April, 1869. s only the undulations in oneplane to pass, the other being stopped. The cause ofthis action is, as yet, not understood. If two plates oftourmaline are superposed, and held before a stronglight, it will be found that the light is alternatelytransmitted and stopped at every go°, when one ofthe plates is rotated. The same effec^t is produced, in a much greaterdegree, by using a pair of crystals of sulphate of iodo-quinine, more commonly known as Herapathite,from its discoverer, the late Dr. William Bird Hera-path. This salt is prepared by a tedious and com- 128 MICROSCOPICAL MANIPULATION. plicated process, and described in a communicationby Dr. Herapath to the Royal Society, and quotedin many microscopical works ( Micrographic Dic-tionary, second edition, p. 590). The obtainingof large regular crystals fit for polariscopes is amatter of great difficulty; and, unless the studentis very expert in chemical manipulation, he is recom-mended not to attempt it. Small specimens fit forFig.
Size: 2236px × 1118px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectmicroscopy, bookyear1
