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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    red lead (menie) and one-third of a part of umber, and then poured oft'. Next take white lead and yellow ochre, well pounded and divided, and mix them together in equal proportions. Successive portions of this mixture must be added to the oil, and well rubbed up and mixed with it, till a tolerably thick fluid is formed, which must be once more thoroughly boiled. If now a preparation has been made, which it is wished to preserve in the chloride of calcium, or any of the five last-mentioned fluids, and if it can, without injury, bear a little pressure, the following manipulation is recom- mended :— If the specimen is moistened with water, which during the prelimnary examination is frequently the case, all superfluous fluid is in the first place removed with a little roll of bibulous paper, or with a camel-hair pencil, such as I have elsewhere recommended. The fluid at a little distance from the object may be wiped off with a cotton or linen rag, and the surface of the glass there made perfectly dry. A certain quantity of the preservative fluid is then placed upon the specimen, and this is most conveniently effected by using a dropping-flask. The amount of fluid should be such that it should afterwards perfectly fill the space beneath the covering plate; the proper quantity is .soon learned by a few trials. Next a (square ?) covering-plate, about two millimetres (ygth of an inch) narrower than the object-slide, should be laid under the centre of the latter,—i.e., immediately beneath the part which it is destined to cover. A pencil is next dipped in the cement, and a square drawn with it upon the glass around the fluid containing the specimen, so that the cement shall extend from one to two millimetres (^k-th to TVth of an inch) within the margins of the covering-plate. The latter is now to be placed upon the specimen, and its margins finally covered with the cement. If there is too much fluid beneath, the superfluity finds a channel for escape ; an opening then takes place in the cement, below the cover, but is again closed, if care be taken to renew the application of the cement to the edges of the cover, when the superfluous fluid has been removed, or has dried up. In about two days, the outer layer of the luting will have become dry, but the inner layer remains soft for many weeks and even months. This is just what constitutes the excellence of the cement, for it never bursts and permits evaporation; and a great number of preparations which I have put up in this manner are at the present time, after the lapse of several years, quite unaltered. It is, however, of importance that the cement shall occupy a portion of the space between the object-plate and its cover; a mere anointing of the edges of the latter is never sufficient. If the specimen be one which will not bear pressure without injury, it must be put up in some kind of cell, the depth of which must be regulated by the thick- ness of the object. The covering-plate must in this case be always smaller in diameter than the space between the outer margins of the cell. First, some preservative solution is placed in the cell, and then the object is laid in it; the upper edges of the cell are then touched with a little of the gutta-percha luting.' 1 The reader will find the receipt for this composition, and directions for mak- ing cells of gutta-percha and caoutchouc, at the end of the present article [Trans.]