liston's isinglass plaster. 
321 
Water and spirit. An ounce of isinglass is sufficient for about 
a square yard of the plaster. 
The following precautions should be observed: — the dis- 
tance between the nails should not be more than an inch and 
a half, otherwise the oil silk will shrink in festoons and will 
not remain flat. The isinglass must be well soaked in water 
before the spirit is added, otherwise it will not make a com- 
plete solution ; and the spirit, when added, must be diluted 
w T ith a portion of the water, to prevent precipitation of the 
isinglass. The brush must be a flat " hog tool," such as is 
used for spirit varnish, and well made, otherwise the hairs 
will be found to come out, and this is an inconvenience, as 
the operation must be performed quickly while the solution 
is warm. The solution, when cold, should be of the consist- 1 
ance of blancmange. 
Repeated experiments have shown that gelatine does not 
answer the purpose as a substitute for isinglass, either alone 
or in any proportions. A sample is on the table, in which 
the first three layers were composed of a mixture of the two 
substances, and the last is pure isinglass ; in another sample 
only isinglass was used, and it will be seen that the latter is 
much more adhesive. 
The oil silk has been, in a great measure, superseded by 
the use of a membrane, consisting of the peritoneal covering 
of the ccecum of the ox, rubbed down and carefully polished 
in the manner in which the common goldbeater's skin is pre- 
pared. The following is the report of this plaster, furnished 
by Mr. Ancrum, Mr. Liston's Assistant at the North London 
Hospital. 
" From the extreme thinness of the plaster, the wounds 
can be examined without its removal. It adheres much bet- 
ter than plaster made with isinglass spread on silk ; and in 
the first instance of its application becomes firmly fixed. It 
is difficult to fix the isinglass plaster spread on silk, unless it 
is very good. From the extreme tenuity of the membrane 
plaster, it is equally unirritating with goldbeater's skin j and 
Vol. vii.— no. iv. it 
