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decomponents into the living Bladder." By S. Elliott Hoskins, M.D 

 Communicated by P. M. Roget, M.D., See. R.S. 



The object of these researches was the discovery of some chemi- 

 cal agent, more energetic in its action on certain varieties of human 

 calculi, and less irritating when injected into the bladder, than any 

 of the fluids hitherto employed. 



These indications not being fulfilled by dilute acids, or other sol- 

 vents which act by the exertion of single elective affinity, the author 

 investigated the effects of complex affinity in producing decompo- 

 sition, and consequent disintegration, of vesical calculi. 



For this purpose an agent is required, the base of which should 

 unite with the acid of the calculus, whilst the acid of the former 

 should combine and form soluble salts with the base of the latter. 

 The combined acids would thereby be set free in definite propor- 

 tions, to be neutralized in their nascent state, and removed out of 

 the sphere of action, before any stimulating effect could be exerted 

 on the animal tissue. 



These intentions the author considers as having been fulfilled by 

 the employment of weak solutions of some of the vegetable super- 

 salts of lead ; such as the supermalate, saccharate, lactate, &c. The 

 preparation, however, to which he gives the preference, is an acid 

 saccharate, or, as he calls it, a nitro-saccliarate of lead. 



The salt, whichsoever it may be, must be moistened with a few 

 drops of acetic, or of its own proper acid, previous to solution in 

 water, whereby alone perfect transparency and activity are secured. 

 He furthermore states, that the decomposing liquid should not ex- 

 ceed in strength one grain of the salt to each fluid-ounce of water, 

 as the decomposing effect is in an inverse ratio to its strength. 



Having by experiments which are fully detailed ascertained the 

 chemical effects of the above class of decomponents on calculous 

 concretions out of the body, the author briefly alludes to the cases 

 of three patients, in each of whom from four to eight ounces of 

 these solutions had been repeatedly, for weeks together, introduced 

 into the bladder, and retained in that organ without inconvenience 

 for the space of from ten to fifty minutes. 



It not being the intention of the author to enter into the medical 

 history of these cases, he merely cites the above facts as sufl[icient 

 to establish the principle originally laid down ; namely, chemical 

 decomposition of phosphatic calculi, by means of solutions so mild 

 as to be capable of retention in the living human bladder without 

 irritation or inconvenience. 



2. " A Method of proving the three leading properties of the 

 Ellipse and the Hyperbola from a well-known property of the 

 Circle." By Sir Frederick Pollock, Knt, F.R.S., Her Majesty's At- 

 torney General. Communicated in a letter to P. M. Roget, M.D., 

 Secretary to the Royal Society. 



In this communication, the author first demonstrates the well- 

 known property of the circle, that if from a point in the diameter 

 produced there be drawn a tangent to the circle, and from the point 



