'xhich 'will happen in the Year 1823. 

 July 23. Moon eclipsed, partly visible. 



4.4.; 



Dig- / /' 



Digits eclipsed 18 13 22,1 from the north part of the 

 earth's shadow. — The moon's centre will pass 9' \0'\9 north 

 of the centre of the earth's shadow at the middle of the eclipse. 

 Aberdeen, Nov. 15, 1823. 



XC. Some Remarks on Uriiiary Calculi, and their Chemical 

 Examination. % John Murray, F.L.S. M.G.S. M.JV.S. 



4'C. Sfc. 



To the Editors of the Philosophical Magazine and Journal. 



rr% J'^th July, 1822. 



Gentlemen, X o the combined genius of Berzelius, Marcet, 

 Henry, Prout, and Brande, we are indebted for almost all we 

 know on the highly interesting subject of urinary calculi. 



The existence of calculi composed of lithate of ammonia^ 

 had been called in question ; but Dr. Prout had since ascer- 

 tained its existence in one case at least — a young person : and 

 to those of immature age it has hence been presumed confined. 

 For my own part I am of opinion no7ie other exists, except of 

 that description. I have not been fortunate, at least, to meet 

 with any composed of lithic acid ; and when we consider the 

 sulnbilitij of this acid, I do not think, prima facie, that it is rea- 

 sonable to expect to meet with it uncombined ifi a concrete form 

 in urine. 



I have drawn my inferences from the numerous examples 

 that have occurred in my chemical examination of these con- 

 cretions ; and must say, that I never met with one that, being 

 mixed witii pure caustic pot assa, did not yield unequivocal evi- 

 dence of the escape of ammonia, on bringing a fcatlier dipt in 

 acid near. If the acetic acid was weak, this indication might 

 not appear ; but \i/nuriatic or nitric acid was employed, there 

 then remained no doubt of the presence of ammonia. Now 



what 



