t 337 ] 



LIV. Description of two Calculi composed of Cystic Oxide, 

 By Thomas Taylor, M,R.C,S, 



To the Editors of the Philosophical Magazine and Journal, 

 Gentlemen, 

 T^HE unfrequent occurrence of calculi composed of cystic 

 oxide, induces me to believe that a description of two 

 specimens of that substance would not be unacceptable to some 

 of your readers. They were found amongj a number of un- 

 examined calculi in the museum of St. Bartholomew's Ho- 

 spital, which, by the kindness of Mr. Stanley, one of the sur- 

 geons of the establishment, and the anatomical lecturer, I was 

 permitted to examine and arrange. 



The larger specimen weighed 740 grs. ; it was of an oval 

 figure, somewhat flattened, measuring one inch nine tenths 

 through the long axis, and respectively one inch four tenths 

 and one inch one tenth through the two short axes. When 

 sawn through it exhibited the confusedly crystallized struc- 

 ture characteristic of this species; the crystals apparently 

 radiated from the centre, their summits projecting at its ex- 

 ternal surface ; these were not however sufficiently defined to 

 render their form evident. The whole had a light yellow 

 colour, its sp. gr. = 1*13. When heated before the blow- 

 pipe, it emitted the peculiar odour of cystic oxide, and left a 

 small ash, which was partially fusible. In all its other che- 

 mical relations it entirely agreed with that substance. 

 Ten grains of the sa wings yielded by analysis : 



Cystic oxide 9*10 



Phosphate of lime 0*38 



Phosphate of ammonia and magnesia... 0*10 

 Animal matter and loss 0*42 



10-00 

 Uric acid could not be detected in it. As far as I am 

 aware this specimen is the largest and finest upon record. 

 Of the other the museum possessed only one half; it was of a 

 lighter colour, and the crystalline structure was not so well 

 marked. Crystallization appeared to have taken place from 

 three points. It measured one inch seven tenths by one inch 

 three tenths. Its exterior was coated in parts by a thin layer 

 of the fusible calculus mixed with a little cystic oxide. Its 

 chemical characters corresponded with the other, but when 

 burnt, it left a much smaller residue, which was alkaline. 

 Unfortunately no history has been preserved of either of 

 these calculi, although there are strong grounds for believing 

 Phil, Mag, S.3. Vol. 12. No, 75. April 1838. 2 I 



