101 



the extent of one-eighth of an inch, and their free extremities being 

 slightly everted and separated from each other by an interval of one 

 tenth of an inch. In experimenting, the united gutta percha tubes 

 were grasped and the projecting platinum points pressed against the 

 surface of the calculus : the jar was then discharged by another 

 person, and a series of such discharges thus passed between the free 

 extremities of the parallel platinum wires while resting upon the 

 surface of the stone. 



With this simple arrangement, fragments a quarter of an inch 

 long were broken off flints immersed in water, and the same force 

 was applied to urinary calculi with the following results : 



Exp. 1. June 7th. A piece of a large lithic acid calculus was 

 placed in a bladder, nearly filled with water, into which the gutta 

 percha bougie containing the wires was then introduced and the 

 neck of the bladder tied round the instrument. The bladder with 

 its contents being placed on a wet board, the projecting platinum 

 wires were then kept in contact with the surface of the calculus 

 and the jar discharged. On opening the bladder and examining the 

 stone, it was found to be broken into numerous fragments by the 

 single discharge. 



Exp. 2. A small phosphatic calculus, very smooth and hard, was 

 experimented upon in a similar manner. The first five discharges 

 produced no perceptible effect, but the sixth split it into at least 

 twenty fragments, and many of these, on being slightly pressed 

 between the finger and thumb, readily broke down. 



Exp. 3. A very large oxalate of lime or mulberry calculus with 

 projecting tubercles was similarly tested, and the first discharge pro- 

 duced a small cavity in the surface to which the wires were applied, 

 separating a considerable quantity of fine sand ; but subsequent dis- 

 charges did not act so efficiently on this very large stone. 



Exp. 4. On the following day, June 8th, the experiment was 

 repeated in the presence of Messrs. Potter, Rayne and Furness, sur- 

 geons in Newcastle, and a small calculus, removed a few months 

 since by the gentleman last mentioned from a young boy, was, after 

 a few trials, split through the centre, one-half being reduced to frag- 

 ments, and the other exhibiting in its interior a dark-coloured 

 nucleus of lithic acid. 



These experiments appear to demonstrate the practicability of 



