Directions for making and preserving microscopical preparations / by Harting of Utrecht.

Date:
[1852]
Catalogue details

Licence: Public Domain Mark

Credit: Directions for making and preserving microscopical preparations / by Harting of Utrecht. 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.

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    G The cell is then completely filled till the fluid even forms a convexity above its margins; if now the cover is applied, the superfluous moisture escapes, and no air remains in the cell. Finally, when the edges are dry, they must be covered with a thick layer of the luting, and with a second a few days afterwards. The method last described is especially applicable to the preservation of in- jected specimens in a solution of arsenious acid.—Vol. ii. p. 350-355. Preparation of Caoutchouc Cells. In commerce we now obtain caoutchouc plates of different thicknesses. The thinnest measure about one millimetre (gktli of an inch), and out of these plates of any required thickness may be formed, as their surfaces adhere perfectly together, especially if previously slightly heated. In a square piece of suitable thickness an opening may be made by means of a scissors, or the centre may be cut out of a disc-shaped piece by means of a hammer and ring-shaped punch. To fasten the caoutchouc ring to the object-slide we use the following luting :— One part of finely-cut gutta-percha is mixed with fifteen parts of oil of turpen- tine, and dissolved in it by gently heating, and constantly stirring, fthe mixture. The solution is then poured through a cloth, to separate some impurities which are always to be met with in raw gutta-percha. To the purified solution there is added one part of shell lac, which, by the aid of gentle heat and constant stir- ring, must be dissolved in it. The heat is then kept up until a drop of the solu- tion let fall upon a cold surface becomes nearly hard. The cement is then ready for use. If it is afterwards found requisite to melt it again, a little oil of turpen- tine should be added before applying the heat. To attach the caoutchouc ring to the glass, proceed as follows:—Lay the ring upon the table, and above it place the glass object-slide, so that the ring occupies the centre of the slide, and a free margin of glass is left around it. A pencil is now to be dipped in the warm luting, and carried over the portion of the glass through which the ring is seen, care being taken to spread the luting in a thin layer, as the superfluous fluid would otherwise flow out from the edges. The ring is now removed from beneath the slide, and laid upon the spot marked out for it with the cement. The plate is next warmed by holding it over fire, and then laid, ring downwards, on a cold piece of mirror glass till the cement has become cool and hard. Gutta-Percha Cells. Gutta-percha, which, like caoutchouc, resists the action of almost all chemical agents, has, besides, the property of becoming soft and plastic in warm water, and can thus be fashioned into any required shape, which it retains on cooling and resuming its former consistence. Gutta-percha sheeting may be procured in commerce, like caoutchouc sheeting, of any thickness, and will be found very use- ful for microscopical purposes. Plates of this substance may be provided of various thicknesses, according to the required depth of the cells,—for example, from -j^jth of a millimetre to three millimetres (^th to ±th of an inch) in thick- ness. These plates must then be cut into square pieces, a little narrower than