The microscope : its history, construction, and application, being a familiar introduction to the use of the instrument, and the study of microscopical science / by Jabez Hogg ; with upwards of five hundred engravings, and coloured illustrations by Tuffen West.

Date:: [1890?]

Credit: The microscope : its history, construction, and application, being a familiar introduction to the use of the instrument, and the study of microscopical science / by Jabez Hogg ; with upwards of five hundred engravings, and coloured illustrations by Tuffen West. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

781/810 (page 739)

$ft manner that the centre of the aperture exactly corre- sponds to the centre of any of the cells nsed in the experi- ments, which are all made to correspond in such a manner that any of them, or this apparatus, may he placed on the stage and he in the proper place without further adjust- ment, which, of course, saves much time and trouble. ^ In the preparation of vegetable colouring matters foi the spectroscope, care must be taken to employ a small quantity of spirits of yvine; filter the solution, and evaporate it at once to dryness at a very gentle heat otherwise if we attempt to keep the colouring matters iu a fluid state they quickly decompose. It is necessary to employ varioixs reagents in developing characteristic spectra. The most valuable reagent is sulphite of soda, which admits of the division of colours into groups. Of the mode of applying reagents, ample directions are given. ]\Ir. Sorby's qualitative analysis is just the kind of thing to employ in detectiag adulterations in many substances met with in commerce, as well as in inquiries where very small quantities of material are at command. By this method we might be able in a few minutes to form a very satisfac- tory opinion, or at least one that might meet all practical requirements, and narrow the inquiry to a surprising' extent; if this can be said even now, surely further search cannot fail to make it most useful in cases where ordioary chemical analysis would be of little or no use; for in this way we may be able to detect the presence of chlorophyll in some of the lower animal forms; as the amoeba, hydra, &c., or, on the other hand, the red colouring matter of the blood, cruorine, in worms, molluscs, and insects. A number of colouriag matters can bo obtained, by using ether, from sponges, polj^zoa, and the crustaceans; these, if examined ia this way, mav give unexpected results. For further information on this interesting subject wa must refer the reader to Mr. Sorby's paper On a Definite Method of Qualitative Analysis of Vegetable and Animal Colourmg Matter by means of the Spectrum Microscope published ia the Proc. Roy. Soc. '^o. 92, 1867. ' 3 B 2$