CYSTIN* 105 



bonic acid gas as 1:2-5. The result of an analysis of this sub- 

 stance in Liebig's laboratory gave its composition 



Carbon, . 39*28 or 5 atoms 3-75 or per cent. 39-48 

 Hydrogen, . 2-95 or 2 atoms = 0-25 ... 2-63 



Azote, . 36-35 or 2 atoms 3-5 ... 36.84 



Oxygen, . 21-42 or 2 atoms 2- ... 21-05 



100.00* 9-5 100- 



So that its formula is C 5 H 2 Az 2 O 2 = 9-5. We have seen be- 

 fore that the formula for uric acid is C 10 H 4 Az 4 O 6 . Now the 

 half of this is C 5 H 2 Az 2 O 3 . So that uric oxide differs from 

 uric acid by containing one atom less oxygen. It may probably 

 be at least occasionally an ingredient in urine ; though it is so 

 very seldom deposited in a solid form. 



SECTION IT. OF CYSTIN. 



This name has been applied to the substances constituting the 

 whole, or almost the whole of the calculus first observed and de- 

 scribed by Dr Wollaston, and called by him cystic oxide, f This 

 calculus Dr Wollaston had obtained about the year 1805 from 

 Dr Reeve of Norwich. It had been taken from his brother, when 

 he was five years old, and at that time was covered by a coating 

 of phosphate of lime very loose in its texture, and consequently 

 very soon separated; Dr Wollaston only met with one other 

 calculus of the same kind. It was in the collection of calculi in 

 Guy's Hospital, and was No. 46 of that collection. It was ex- 

 tracted by the usual operation from William Small, a man of 

 36 years of age. Dr Henry of Manchester afterwards found 

 two calculi in his collection belonging to the same species ; and 

 Dr Marcet detected cystic oxide calculus in no fewer than three 

 different cases, of which he has given a description.^ Some years 

 ago I was kindly presented with another calculus belonging to 

 the same species by Dr Apjohn, which had been extracted by the 

 usual operation in Dublin. M. Lassaigne, in 1823, announced 

 that fie had found the same substance in a calculus from a dog. 



* There must be a typographical error in the data from which this composi- 

 tion was deduced. For when we calculate from them the result differs enor- 

 mously from the statement in the text, deduced by Liebig from his analysis. 



f Phil. Trans. 1810, p. 223. 



$ On the Chemical History and Medical Treatment of Calculom Disorders^ 

 p. 28. 



Ann. de Chim. et de Phys. xxiii. 328. 



