Different modes of mounting may be employed with advantage; for instance, entomological specimens, as legs, wings, spiracles, tracheæ, ovipositors, stings, tongues, palates, corneæ, should be mounted in balsam; the trachea of the house-cricket, however, should be mounted dry. Sections of bone may either be mounted dry or in a fluid. Other objects, as sections of wood and stones of fruit, exhibit their structure best in Canada balsam. In mounting entomological specimens, the first thing, of course, is the dissection of the insect. This is best accomplished by the aid of a dissecting microscope, a pair of small brass forceps, and finely-pointed scissors; the parts to be prepared and mounted should first be carefully detached from the insect with the scissors, then immersed in a solution of caustic alkali (_liquor potassæ_) for a few days, to soften and dissolve out the fat and soft parts. The length of time necessary for their immersion can only be determined by experience, but, as a general rule, the objects assume a certain amount of transparency when they have been long enough in the alkali; when this is ascertained, the object must be placed in a proper receptacle and put by to soak for two or three hours in soft or distilled water. It should then be placed between two slips of glass, and gently pressed till the softer parts are removed. Should any adhere to the edge of the object, it will be necessary to wash the specimen carefully in water, a process that will be much assisted by the delicate touches of a camel’s-hair brush. Place the object now and then under the microscope to see that all extraneous matter is removed, and when this is accomplished take the specimen up carefully with the camel’s-hair brush, or a lifter, and place it on a piece of very smooth paper (thick ivory note is the best for the purpose), arrange it carefully with the brush and a finely pointed needle, place a second piece of paper over it, and press it flat between two slips of glass, and compress it by a small spring clip (Fig. 264). A dozen clips may be had for a few pence. When _thoroughly_ dry (which it will probably be in about twenty-four hours, if in a warm room), separate the glasses, and gently unfold the paper; then, with a little careful manipulation, the object may be readily detached, and placed in a little spirit of turpentine, where it should be allowed to remain until rendered transparent and fit for mounting. The time during which it should remain in this liquid will depend on the structure; some objects, such as wings of flies, will be quickly permeated, while horny and dense objects require an immersion of a fortnight or even longer. A pomatum pot with a _concave_ bottom and well-fitting lid will answer admirably for conducting the soaking process in; and it is well, in preparing several specimens at a time, to have two pots, one for large and medium, the other for very small objects, otherwise the smaller will adhere to the larger.