7b APPENDIX. 



object : should air-bubbles arise, they may be broken by 

 touching them with the point of a needle ; they will, how- 

 ever, frequently disperse of themselves as the balsam dries. 

 The thin glass cover, being warmed, should now be placed 

 upon the object, and a slight pressure applied to get rid of 

 the superfluous balsam. Place the slide in some warm spot 

 to dry ; an oven will do very well, if the fire has been some 

 time removed and there is not sufficient heat to make the 

 balsam boil. 



In a short time the balsam round the edges of the cover 

 will be hard enough to admit of the greater part being 

 scraped off with a knife ; the remainder may be got rid of 

 by wiping the slide with a rag dipped in turpentine or ether. 

 The finishing touch consists in labelling the object with its 

 proper name. It will be found advantageous to place the 

 common name of the specimen at one end of the slide, and 

 its scientific name at the other. 



Some persons prefer covering their slides with ornamental 

 paper, which may be obtained of almost any optician. 

 Others prefer the glass without any covering at all. In the 

 latter case the edges of the slide should be ground, the 

 round thin glass covers used, and the name scratched upon 

 the slide with a writing diamond. In the former, the edges 

 of the slide, being covered with paper, need not be ground, 

 but square thin covers should be used instead of round ones, 

 and the name written with pen and ink in the square 

 places allotted at each end of the slide. 



LEGS or INSECTS (Plate 7, Figs. 198, 199, 200; Pi. 8, 

 Figs. 208, a, b, c; Fig. 209, a, b; Figs. 213, 214). These 

 require a little more preparation than wings ; and as they 

 possess some thickness, and are mostly opaque, besides 

 being of a hard, horny character, they should be placed for 

 a fortnight or even longer in liquor potassce : this will soften 

 the tissue and dissolve the muscles and other matter con- 

 tained within them, so that by gently pressing the limb 

 between two slips of glass the interior substance will 

 gradually escape, and may be removed by repeated wash- 

 ings. The squeezing process, however, must be conducted 

 gently, to prevent any rupture : perhaps the best plan is to 

 plunge the slips of glass into a basin of clean water, when 

 all impurities oozing out from the pressure will sink to the 

 bottom. Should the leg not be sufficiently softened to be 

 squeezed quite flat, it must be again placed in the solution 

 for a longer period, until this result be obtained. On 

 removing it from the potash it should be well washed with 



