t¥93° on the cacutchowe: 30% 
space anlage ofan hour or 26 minutes. It isthus in some 
measure softened, tho’ not difsolved ; and acquires a kind 
of transparency towards the edges. He then rolls it up. 
firmly upon a mould prepared for the purpose, so as to’ 
make the edges overlap each cther a little, and covers the 
whole mould with an uniform unbrokencoating, and imme- 
diately wraps it all over with a piece of ribbon or tape, so 
as to comprefs the whole very firmly. In this state he al- ‘ 
lows it to remuin till it be quite dry ; and then, on taking 
off the bandage, he finds that the whole forms an uniform 
compact coating, which retains the & ape of the mould after 
it is withdrawn, and has the same Kind of flexibiliry with 
thé caoutchouc in its natural state. When the mould is 
a smooth cylimuer like a wire, which he employed, he found 
it could be withdrawn merely by dipping the whole for a 
few minutes in boiling water, and then pulling it out. 
In this way he thinks catheters, &c. may be formed as 
good as those that have hitherto been made by a solution of 
caoutchouc in ether, and at a much smailer expence 3 and 
in the same way may be constructed tubes and cases of va- 
rious ferms, for many purposes in economy gud arts, a few 
of which thail be here briefly specified. : 
Pumps for acids, and tubes of various sorts, 
It has been long a desideratum among those who deal 
in acids, to find a pump that could be conveniently em- 
ployed for taking them from one veisel into another. Pers 
haps it may be pofsible to supply that want by the contri- 
vance above specified. For this purpose let a cylinder of 
the size wanted be provided; cover it as far as the length 
of the tube required. To give the tube the firmaefs ree 
quired in the bore of a pump, teke a pipe of thin tin plate, 
formed cylindrically, but having several small slits along 
its surface the whole way, of the precise breadth wanted; 
without being cemented. Let it then be laid over the cylin- 
der covered with the cacutchguc, and firmly bound round 
