214 MOUNTING OBJECTS IN CANADA BALSAM. 



cooled, and at the same time applying a gentle pressure to the 

 covering-glass, an ingenious and convenient Mounting Instrument 

 has been devised by Mr. James Smith. This consists of a plate of 

 brass turned up at its edges, of the proper size to allow the ordi- 

 nary glass slide to lie loosely in the bed thus formed ; this plate 

 has a large perforation in its centre, in order to allow heat to be 

 directly applied to the slide from beneath ; and it is attached by a 

 stout wire to a handle (Fig. 99). Close to this handle there is 

 attached by a joint a second wire, which lies nearly parallel to the 

 first, but makes a downward turn just above the centre of the 

 slide-plate, and is terminated by an ivory knob ; this wire is 

 pressed upwards by a spring beneath it, whilst, on the other 

 hand, it is made to approximate the other by a milled-head 

 turning on a screw, so as to bring its ivory knob to bear with 

 greater or less force on the covering glass. The use of this 

 arrangement will be presently explained. — If such a mounting 

 instrument be not employed, the wooden Slider-Forceps of Mr. 

 Page (Fig. 100) will be found extremely convenient; this, by its 



Fig. 100. 



Slider Forceps. 



elasticity, affords a secure grasp to a slide of any ordinary thick- 

 ness, the wooden blades being separated by pressure upon the brass 

 studs ; and the lower stud, with the bent piece of brass at the 

 junction of the blades, affords a level support to the forceps, which 

 thus, while resting upon the table, keeps the heated glass from 

 contact with its surface. This instrument will be found par- 

 ticularly useful when the balsam has to be hardened on the slide, 

 for the purpose of cementing to it bodies of which thin sections 

 are to be made. — Besides a pair of fine-pointed steel Forceps for 

 holding the object to be mounted, there should be another of a 

 commoner kind for taking-up the glass cover, the former being 

 liable to be soiled with balsam. — A pair of stout Needles mounted 

 in handles (§ 135) will be found indispensable, both for manipu- 

 lating the object, and for breaking or removing air-bubbles ; and 

 if these handles be cut to a flat surface at the other extremity, they 

 will serve also to press-down the glass covers, for which purpose 

 a pointed stick also is useful. — For holding-down these covers 

 whilst the balsam is cooling, if the elasticity of the objects should 

 tend to make them spring-up, such as are not provided with 

 the Mounting Instrument above described may advantageously 

 employ the Spring Clip (Fig. 97) ; or, if its pressure is not firm 



