106 ANIMAL OXIDES WITH AZOTE NOT OILY. 



But his analysis differs so much from that of cystic oxide by Dr 

 Prout, that I consider it impossible that both operated upon the 

 same substances. Two cystic oxide calculi exist also in the Muse- 

 um of St Bartholomew, and have been described by Mr Taylor.* 

 One of them weighed 740 grains. It is, therefore, the largest 

 calculus of this species hitherto observed. It was analyzed by 

 Mr Taylor, and found composed of, 



Cystic oxide, . . 91 



Phosphate of lime, . . 3-8 



Ammonia-phosphate of magnesia, . 1-0 

 Animal matter, . . . 4-2 



100-0 



About the year 1836, M. O. Henrie got two very small calculi 

 of the same species, which had been passed with great pain by 

 an individual 50 years of age. f 



Cystic oxide calculi have a pale yellow colour, are translucent, 

 and appear irregularly crystallized. They are not composed of 

 distinct laminae, but constitute one compact mass. They have 

 also a peculiar glistening lustre, like that of a body having a 

 high refractive density. 



When cystic oxide is submitted to destructive distillation, it 

 yields foetid carbonate of ammonia, partly fluid, and partly in a 

 solid state, a heavy foetid oil, and there remains a black spongy 

 coal, much smaller in proportion than is found after the distilla- 

 tion of uric acid calculi. 



Under the blowpipe it may be distinguished by the smell, which 

 at no period resembles that of hydrocyanic acid ; but, in addition 

 to the usual smell of burnt animal substances, there is a peculiar 

 fcetor quite different from that of any other substance. 



Cystic oxide is not soluble in water, alcohol, acetic acid, tar- 

 taric acid, citric acid, nor in bicarbonate of ammonia. It is dis- 

 solved in considerable quantity by muriatic, nitric, sulphuric, 

 phosphoric, and oxalic acids. It is also dissolved readily by pure 

 alkaline menstrua, by potash, soda, ammonia, and lime-water. 

 Even bicarbonates of potash and soda dissolve it 



The combination of cystic oxide with acids may be made to 

 crystallize without difficulty, and they form slender spiculae ra- 

 diating from a centre, which readily dissolve again in water, un- 



* Phil. Mag, (3d series) xii. 237. f Jour, de Pharm., xxiii. 71. 



