220 Royal Society, 



acid by Price's test, and also by decolorizing a deep solution of 

 indigo. 



Thus before the salt of ammonia was taken no nitrous acid could 

 be detected in the urine, whilst after the ammonia nitrous acid was 

 proved to be present, not only by Price's test, l)ut by the indigo test 

 also. 



In conclusion, it results from these experiments, — 1st, That in 

 Price's test sulphurous acid produces exactly the opposite effect to 

 nitrous acid, and even hinders nitrous acid from liberating iodine 

 from hydriodic acid. 



2ndly. That phosphoric acid, when mixed with urine containing 

 nitre and distilled very low, does liberate nitrous acid ; though when 

 used instead of sulphuric acid, it does not enable the nitrous acid to 

 be detected so readily as when the latter acid is employed. 



Hence the experiments performed in Professor Lehmann's labo- 

 ratory by Herr JafFe*, do not invalidate Price's test for nitrous acid 

 in the way Professor Lehmann supposes ; and by again repeating 

 some of my former experiments, I still arrive at the conclusion that 

 when ammonia is taken into the body nitric acid may be detected 

 in the urine, but that the quantity which can be made to appear is 

 so small that the most delicate method is required for its detection. 

 This however is no proof that a much larger quantity may not be 

 lost in the process for obtaining it from the urine. 



" On the Disintegration of Urinary Calculi by the Lateral Dis- 

 ruptive Force of the Electrical Discharge." By George Robinson, 

 M.D., Licentiate of the Royal College of Physicians of London, and 

 Lecturer on Medicine in the Newcastle-upon-Tyne College of Prac- 

 tical Science. 



The great and diversified powers of electricity have long suggested 

 the possibility of its being employed as a means of effecting the de- 

 struction of calculi in the human bladder, and thus obviating the 

 necessity for the painful and dangerous operation of lithotomy. 

 But the attempts hitherto made in this direction have contemplated 

 the solution of the stone through electrolytic action rather than its 

 disintegration by the mechanical force of the electrical discharge. 

 A moment's reflection will however suffice to convince us that the 

 force which shatters a steeple or cleaves an oak, is also capable of 

 reducing to fragments the largest urinary concretion. Nor can I 

 imagine any other than the following sources of objection to the prac- 

 ticability of employing this force for the purpose of breaking down 

 vesical calculi in situ, namely, 1 . the danger to the living structures 

 from the necessity of using a powerful discharge ; 2. the difficulty of 

 conveying the force to the required spot, or in other words, causing 

 the discharge to pass through the calculus. The first objection is in 

 a great measure met by the fact of our being enabled to regulate with 

 the utmost precision the degree of intensity of the discharge, and it 

 would be almost entirely removed were it possible to apply the dis- 

 ruptive force of electricity without any portion of the body being 

 included within the circuit traversed by the electrical current. The 

 * Erdmann's Journal, vol. lix. p. 238, 1853. 



