268 Mode for passing Calculi from the Bladder [Oct. 



Sulphuretted hydrogen 2* 125 



Phosphuretted hydrogen 1'625 



Bihydroguret of phosphorus 1*75 



It is obvious from the preceding tables that there are four 

 gases which have the same specific gravity and the same atomic 

 weight. These are 



Sp.gr. Weight of atoms. 



Azote 0-9722 i-75 



Carbonic oxide 0-9722 1-75 



Olefiant gas 0*9722 1-75 



Bihydroguret of phosphorus . . 0*9722 1-75 



The specific gravity of carburetted hydrogen gas is half that 

 of oxygen gas, and the weight of its atom the same as that of 

 oxygen. The specific gravity of vapour of sulphur is the same 

 as that of oxygen gas, and the weight of its atom double that 

 of oxygen. The specific gravities and atomic weights of protox- 

 ide of azote and carbonic acid gases are the same. 



Article II. 



A Mode suggested for passing Calculi from the Bladder by the 

 Aid of Atmospheric Fressure. 



(To Dr. Thomson.) 



SIR, Stocl§rove,u4ug. 3, \820. 



The writer of this has lately seen in one of the public journals 

 the description of a new instrument called by its inventor * a 

 Dilator, by which any part of the urethra may be dilated with- 

 out aft'ecting other parts of it by means of an elastic substance 

 charged with air, for the removal of stricture, and to facilitate the 

 passage of calculi from the bladder. Now whatever may be the 

 merit of the instrument itself, or whatever chance there may be 

 (and of this there is reasonable hope) of its leading to new and 

 useful expedients, the inventor has at least the merit of directing 

 the public attention to mechanic remedy in this class of com- 

 plaints. Chemistry has done much of late towards pointing out 

 the true principle on which alone medical treatment can be of 

 any use. Let mechanic science also by the invention of new, 

 or by the improvement of old instruments assist the progress of 

 relief. The object of this paper is to suggest the plan of 

 another instrument for the removal of the calculus, after the 

 dilator has prepared a passage for it, of sufficient powder, it is 

 presumed, to draw away any calculi which the dilated calibre of 



* .Mr. Arnott, of Bedford-square, London. 



