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
