498 ON THE INTERDEPENDENCE OF SCIENCE 



securely, while the ligature around the vessel becomes gradually absorbed and 

 replaced by a ring of living tissue. The threads, instead of being left long as 

 before, could now be cut short, and the tedious process of separation of the 

 ligature, with its attendant serious danger of bleeding, was avoided. 



Undiluted carbolic acid is a powerful caustic ; and although it might be 

 employed in compound fracture, where some loss of tissue was of little moment 

 in comparison with the tremendous danger to be averted, it was altogether 

 unsuitable for wounds made by the surgeon. It soon appeared, however, that 

 the acid would answer the purpose aimed at, though used in diluted forms 

 devoid of caustic action, and therefore applicable to operative surgery. Accord- 

 ing to our then existing knowledge, two essential points had to be aimed at : 

 to conduct the operation so that on its completion the wound should contain 

 no living microbes, and to apply a dressing capable of preventing the access of 

 other living organisms till the time should have arrived for changing it. 



Carbolic acid lent itself well to both these objects. Our experience with 

 this agent brought out what was, I believe, a new principle in pharmacology — 

 namely, that the energy of action of any substance upon the human tissues 

 depends not only upon the proportion in which it is contained in the material 

 used as a vehicle for its administration, but also upon the degree of tenacity 

 with which it is held by its solvent. Water dissolves carbolic acid sparingly 

 and holds it extremely lightly, leaving it free to act energetically on other things 

 for which it has greater affinity, while various organic substances absorb it 

 greedily and hold it tenaciously. Hence its watery solution seemed admirably 

 suited for a detergent lotion to be used for destrjoying any microbes that might 

 fall upon the wound during the operation, and for purifying the surrounding 

 skin and also the surgeon's hands and instruments. For the last-named purpose 

 it had the further advantage that it did not act on steel. 



For an external dressing the watery solution was not adapted, as it soon 

 lost the acid it contained, and was irritating while it lasted. For this purpose 

 some organic substances were found to answer well. Large proportions of 

 the acid could be blended with them in so bland a form as to be unirritating ; 

 and such mixtures, while perpetually giving off enough of the volatile salt to 

 prevent organic development in the discharges that flowed past them, served 

 as a reliable store of the antiseptic for days together. 



The appliances which I first used for carrying out the antiseptic principle 

 were both rude and needlessly complicated. The years that have since passed 

 have witnessed great improvements in both respects. Of the various materials 

 which have been employed by myself and others, and their modes of application, 

 I need say nothing except to express my belief, as a matter of long experience, 



