232 THE MICROSCOPICAL NEWS. 
very simple, hence the low price at which it can be sold ; and in 
practice it has been found to work admirably. 
MR. CATHCART’S DIRECTIONS FOR USE. 
1. Place a few drops of mucilage (1 part gum to 3 parts water) 
on the zinc plate (H). 
2. Take a piece of the tissue to be cut of about 4% of an inch 
thickness, and press it into the gum. 
3. Fill the ether bottle (J) with anhydrous methylated ether, 
and push the spray points into their socket (E). All spirit must of 
course have previously been removed by soaking the tissue for a 
night in water. It should afterwards be soaked in gum for a like 
time before being cut. 
4. Work the spray bellows briskly until the gum begins to freeze ; 
after this, work more gently. Be always careful to brush off the 
frozen vapour which, in a moist atmosphere, may collect below the 
zinc plate. If the ether should tend to collect in drops below the 
plate, work the bellows slower. 
5. Raise the tissue by turning the milled head (G), and cut by 
sliding the knife along the glass plates. 
6. After use be careful to wipe the whole instrument clean. 
7. Should the ether point become choked, clear by means of a 
piece of fine wire. 
8. The instrument is intended for use with methylated sulphuric 
ether. 
g. In clamping the instrument to a table, or other support, care 
should be taken that the zinc plate is in a horizontal position. If 
the plate be not horizontal, the gum will tend to run to one side. 
If, after the ether point has been cleared by the fine wire, it 
should still fail to act properly, it had better be returned to the 
maker for re-adjustment. For this purpose the spray points ony 
need be sent. 
At a temperature of 50° Fah., the instrument, if in proper order, 
should freeze a quantity of gum, half an inch in diameter and 
about one quarter inch thick, in two minutes. The instrument 
will give the best results when worked in a co/d and dry atmosphere. 
Mr. Coppock, of New Bond Street, is the maker of this 
instrument. 
