1893.] Mr Eichholz, On Urobilin. 51 



Maly's hydrobilirubin differs from true urobilin and how con- 

 sequently the identity of Hoppe Seyler's and Nencki and Sieber's 

 urobilin from hsematin reduction becomes doubtful, it was shewn, 

 in spite of statements to the contrary by McMunn and Le Nobel, 

 that it is possible by complete reduction of both bilirubin and 

 hfpmatin to obtain substances in each case accurately resembling 

 urobilin. 



Monday, February 18, 1893. 



Professor T. McK. Hughes, President, in the Chair. 



W. G. P. Ellis, M.A., St Catharine's College, was elected a 

 Fellow of the Society. 



The following Communications were made to the Society : 



(1) Note on the stability of rotating liquid spheroids. By 

 G. H. Bryan, M.A., St Peter's College. 



In his paper " On the stability of Maclaurin's spheroid " 

 Mr Basset has characterized as " incorrect " one of the state- 

 ments in my paper " On the Stability of a Rotating Spheroid 

 of Perfect Liquid* ". The statement in question refers to the 

 negative value of the quantity 



which enters into the criteria of stability, and is to the effect 

 that " Its meaning is that the spheroid is more oblate than that 

 form for which the angular velocity is a maximum." 



While admitting that Poincare was in error in overlooking 

 the fact that the angular momentum and not the angular velocity 

 should be kept constant, I am unable to see how Mr Basset 

 arrives at this conclusion. On the contrary, the following con- 

 siderations seem to leave no doubt as to the correctness of my 

 interpretations. 



The angular velocity ca is connected with the quantity ^ 

 which defines the eccentricity of the spheroid, by the relation 



ft,^ = 27rp7 (3^^ -f cot-' ^ - 3^^t; 

 day" 



^^=2,rp7 



(9r>l)cot-r-^^^-6f 



(r + 1) "^-f^ = 27rp7 [(9^^ + 10^+ 1) cot- ^- (9r + 70] 



= 27rp7 [(Sr + 1) {(8^^ + 1) cot-^ r- Sri -H 4^{r cot-'r- 1}] 



= 87rp7{^,(r).g.(D-i'i(r).gx(0}t 



* Proceedings Royal Society, Vol. xlvii. p. 371. 



t Phil. Trans. Vol. clxxx. A. p. 197 (50). J Proc. R. S. Vol. xlvii. p. 369. 



