140 SUMMARY OF CURRENT RESEACCHES RELATING TO 



mountings are very free from this trouble, though all made with wax- 

 bottomed and asphalt-covered cells. The reason of this, he thinks, is 

 that the cells are mostly made a long time before they are used ; his 

 business being such that he can only devote time to microscopy in the 

 mornings and evenings. Hence most of the work is interrupted by 

 twelve-hour intervals. To save time, a lot of cells are made up at 

 once, using double-thick pond-lily wax and brass curtain rings, some- 

 times a little flattened. 



To make the cell, place the ring on the wax and press it down with 

 a slip ; then with a wet penknife-blade, cut around the ring outside, 

 and lift it out. The disk of wax is then punctured from below with a 

 needle in two or three places near the middle, and if not already raised 

 a little in the centre, it is gently bent with the finger, so that when 

 placed on the slide it will touch only at the edges. The ring is now 

 placed on the centre of a slip in the turntable, and gently pressed to 

 make it adhere. Then removing the slide, it is held over a lamp, 

 keeping it level ; the wax first softens at the ring, and as the softening 

 proceeds towards the centre, the air escapes through the needle-holes, 

 and blisters are prevented as the wax settles down upon the slide. 

 Before the wax actually melts, the slide should be removed, and 

 returned to the turntable to see if it is still centered. If the wax does 

 melt, no harm is done unless the ring slides from its place before it 

 cools. When cool the ring is firmly fixed, and it is then coated on the 

 turntable with Brunswick black, though perhaps shellac would be 

 safer from liability to the " sweating." Having prepared from four to 

 six dozen cells of different sizes, they are laid away in drawers, and 

 after a time, three days to three weeks, as the case may be, the cells 

 are coated again. And when this second coat is dry, any time after a 

 week, the cells are fit for use. In mounting he uses nothing to fasten 

 the object to the wax, but presses it down with a needle or shaved 

 splint of whalebone, or the finger-end in many cases. Objects in fluid 

 are to be allowed to evaporate in the cell, leaving them covered from 

 one night to a day or two, as may be. When the cells are covered, 

 covers are used cut by the author's cover-cutter, just large enough to 

 rest inside the brass rings without falling through. Then the angle 

 between the edge of cover and top of the cell is filled up with wax by 

 means of a pointed knife-blade, using the wax as jiutty is used on a 

 window. The mounts can now be left for finishing till a leisure time, 

 but it is desirable to apply a light coat of cement before putting them 

 away, and at any time afterward when time can be found he goes over 

 them again, and usually a third time before finishing. 



Simple Device for Handling Thin Covers. — Mr. J. C. Douglas 

 writes, that he has long wanted a simple appliance for picking covers 

 out of the liquid in which they may be soaking, selecting them 

 from their box, placing them flat upon the object to be examined 

 or moimted, and picking them off the slide when necessary after 

 examining the object covered. Forceps and needles have grave 

 inconveniences. Chase's mounting forceps * simply drop on the 



* See this Journal, iii. (1880) p. 508. 



