290 MANIPULATION. 



first coating is always best of asphalte alone, as it adheres 

 more strongly to the glass than the gold-size, which is apt to 

 peel off unless it is baked, as soon as the first coat is laid on. 

 This apparatus is also of great assistance in cementing on the 

 covers, both of the cells made by it and also of the ordinary 

 glass celts, as they are not only cemented on much more neatly 

 than by hand, but what is of more importance, with, less dan- 

 ger of disarranging the contents. 



Mr.- Shadbolt has also a method of making cells of greater 

 thickness, of marine-glue, mentioned at page 275 ; his process 

 is as follows : — Having procured two pill slabs of about 6 inches 

 square, of marble, glass, or earthenware, as flat as possible, 5 

 gun punches, the largest being | of an inch in diameter, and 

 the smallest | of an inch, the others intermediate, also a small 

 pipkin ; a little of the glue is gently melted in the pipkin, the 

 two pill slabs are then wetted with cold water, and some of 

 the melted glue is dro23ped on one of them, and the other is 

 immediately pressed upon it, so as to force it into a thin sheet, 

 the thickness depending on the amount of pressure. In a few 

 moments the slabs may be separated ; sometimes they adhere 

 so strongly, notwithstanding the water, that the assistance of 

 a large dinner knife is required to disunite them. 



When a sufficient number of sheets has been thus formed, 

 lay one on a piece of flat wood or cardboard, and with the largest 

 punch pressed on it, cut it into a number of discs ; with the 

 second sized punch cut out the centre of these, leaving only 

 rings of glvie ; the third sized punch may be used on the smaller 

 discs cut out of the large ones, and so on to the smallest ; thus 

 four sized rings will be formed. It is now necessary to hardeji 

 the rings of glue, and to fix them to the glass slides, (vhich may 

 be both done at one operation. Place the requisite number 

 of glass slips on a tray or piece of wood, and make them 

 tolerably hot in an oven; as soon as they are taken out, 

 carefully drop a ring of glue on each, in the exact place where 

 required, the rings of glue will immediately melt, and by 

 keeping up a gentle warmth may be made as hard as is 

 desired ; they will also be very firmly attached to the glass by 

 this process. The slides must be kept the whole time in a 



