I have stated that the balsam is usually applied to the slide and objects with a “bluntly-pointed glass rod;” but for the purpose of drawing the balsam from the bottle, and conveying it to the desired place, Dr. Carpenter uses a glass syringe with a _free_ opening. These are his instructions:--“This (the syringe) is most readily filled with balsam, in the first instance, by drawing out the piston, and pouring in balsam previously rendered more liquid by gentle warmth; and nothing else is required to enable the operator at any time to expel precisely the amount of balsam he may require, than to warm the point of the syringe, if the balsam should have hardened in it, and to apply a very gentle heat to the syringe generally, if the piston should not then be readily pressed down. When a number of balsam objects are being mounted at one time, the advantage of this plan in regard to facility and cleanliness (no superfluous balsam being deposited on the slide) will make itself sensibly felt.” When the “mounting” is thus far accomplished, the outer “wall” of balsam may be roughly removed after a few hours have elapsed; but great care is necessary lest the cover be moved or interfered with in any way. In this state it may be left for the final cleansing until the balsam becomes hard, which takes place sooner or later, according to the degree of warmth it has been subjected to. A mantel-piece, or some place about equal to it in temperature, is the best suited to this purpose; and when the requisite hardness is attained, it may be proceeded with as follows:--With a pointed knife the balsam must be scraped away, taking care that the thin glass be not cracked by the point getting _under_ it. If used carefully, the knife will render the slide almost clean; but any minute portions which still adhere to the glass must be rubbed with linen dipped in turpentine or spirit. If the balsam is not very hard, these small fragments are readily removed by folding a piece of paper tightly in a triangular form with many folds, and damping the point with which the glass is rubbed. As the paper becomes worn with the friction, the balsam will be carried off with it. In some cases I have found this simple expedient very useful.