174 THE ADDRESS IN SURGERY DELIVERED BEFORE 



constitution. But in the flasks with bent necks the fluid remains to this day 

 entirely unaltered.^ I regret that the distance from Edinburgh to Plymouth 

 is too great to permit me to bring these objects before you. One perilous 

 journey they have already had, when I took them from Glasgow to Edinburgh 

 nearly two years ago, nursing them carefully during the railway journey, to 

 the amusement of my fellow travellers ; and in the drive from the station to 

 my house the violent rocking of the vehicle churned up their contents till the 

 upper part of the body of each flask was full of a frothy mixture of the putrescible 

 liquid with the atmospheric gases ; yet no harm resulted, and the fluid in the 

 bent flasks still retains its original pellucid clearness and pale hue. Bringing 

 these in imagination before you, as represented in this diagram, consider what 

 these facts imply. Let us not push them one tittle beyond their inevitable 

 interpretation. The drops of moisture deposited in the bent tubes from con- 

 densation of the steam when the lamp was removed dried up in a few days, 

 so that the necks have been for nearly four years open and dry from end to 

 end. Comparing the capacity of the part of the body of the flask containing 

 air with that of the narrow neck, it is manifest that a considerable portion of 

 fresh air has passed into the flask every night, in consequence of the fall of the 

 temperature, a corresponding portion passing out again by day, though not 

 the same which entered ; for the diffusion of gases would ensure its mixing 

 freely with that previously present. Hence, during nearly four years this 

 putrescible liquid, this boiled urine, has been freely exposed to the influence 

 of the atmospheric gases, yet it has not putrefied. About half a year after 

 the commencement of the experiment, I decanted a little of the liquid from 

 one of the bent flasks into a wine-glass, and found it sweet in odour and faintly 

 acid to test-paper, while an honest search with a powerful glass failed to detect 

 even the minutest organism. Covering the glass to prevent evaporation, I found 

 it in two days stinking, while under the microscope it already teemed with 

 various organisms, and a few days later it showed fungi to the naked eye. Thus 

 the fluid was demonstrated to be still putrescible and a favourable nidus for 

 organic development ; yet both these changes have been prevented for nearly 

 four years by the circumstance that the air, in gaining access to it, had to pass 

 through a narrow bent tube of clean dry glass. Now such a tube could not by 

 possibility arrest any atmospheric gas. It cannot possibly have stopped any- 

 thing but the atmospheric dust. It follows, therefore, not as a matter of theory, 

 but as an inevitable inference from fact, or, in other words, as a truth, that, 

 so far as this particular instance of a putrescible liquid is concerned, both the 



* Some minute shining crystals have of late been deposited on the bottom of the flasks, probably 

 from condensation through the very slow evaporation constantly going on. 



