INTRODUCTION XXXlil 
edge of it was then raised, the incision made, and the curtain of lint let fall, the 
abscess being evacuated by gentle pressure under its protection. The anti- 
septic was not injected into the cavity of the abscess, experience having shown 
that while such injection was quite superfluous, it could only do mischief by 
causing irritation. A narrow strip of lint dipped in the same oily solution 
was introduced through the incision to prevent primary union and at the 
same time to act as a drain. On removal of the oily antiseptic curtain a 
dressing of the putty, spread on a piece of block-tin, was immediately fixed 
over the incision by adhesive plaster and bandaged to the part. The thin 
discharge flowed out beneath the edges of the putty, which was renewed 
yonce. a. day. 
The use of block-tin was not long continued: the putty was spread upon 
calico, and in this form the dressing was extended to the treatment of incised 
wounds made by the surgeon. Although the results obtained with this anti- 
septic putty dressing were strikingly satisfactory, its employment was attended by 
certain practical inconveniences, and Lister devoted a great deal of patient 
research to devising a substitute which should be not less effective to achieve 
the main object in view, but more convenient in use. After many experiments, 
he found a suitable material in shellac prepared in the following manner. When 
mixed with carbolic acid (rz to 4) shellac forms a flexible mass from which, 
as from a reservoir, the acid is constantly and not too rapidly given off. The 
practical objection to its use in this form was that it adhered too firmly to the 
skin, but this was overcome by spreading the mixture on calico and then painting 
a solution of india-rubber in benzene over thesurface. The thin layer of india- 
rubber left on the surface of the shellac when the benzene evaporated prevented 
the plaster sticking to the skin, while the carbolic acid as it was liberated from 
the shellac passed freely through it. This new dressing presented many practical 
advantages. It was not disintegrated by friction like putty, and being much 
lighter was not only far less cumbrous, but could be more easily maintained 
in position ; while, further, it was always ready for use, whereas the putty had to 
be specially prepared by the surgeon on each occasion. It was adopted alike for 
the treatment of injuries, abscesses, and incised wounds. In the last the method 
of treatment was as follows : During the performance of an operation the wound 
was from time to time irrigated with carbolic lotion, and more especially was 
filled with this lotion while it was being stitched up. The lotion was then 
expressed from the wound, the lac-plaster immediately applied, overlapping the 
surface to a considerable area around the wound, cloths being placed about the 
margin in order to absorb the discharge that passed out from under the lac-plaste! 
Attention was also paid to the drainage of wounds, and for this purpose a strip 
LISTER I G 
