of the forty-one known L. P.'s, thirty would be in one semicircle, is 

 about -5-^ ; and that of the forty ascending nodes, thirty-one would 

 be in one semicircle, is about 4 ^ 1 . Thus the probability that there 

 is some influence causing a tendency to one semicircle, ascertained 

 from the facts before us, is very strong: for, for the L. P.'s, the odds 

 are about 660 to 1, and for the ascending nodes about 4430 to 1 in 

 favour of such a supposition." But after all it may be an accidental 

 coincidence; as, consistently \vith the laws of planetary motion, 

 such a congregation of perihelia or nodes may occur at periods 

 exceedingly remote. The further consideration of this subject must 

 be left to analysts, of leisure and inclination to pursue it. 



II. " On Circumstances modifying the Action of Chemical 

 Affinity." By J. H. GLADSTONE, Ph.D., F.R.S. Re- 

 ceived February 1, 1855. 



The question intended to be solved in this communication is, 

 what takes place when two binary compounds AB and CD are 

 brought together under such circumstances that both they them- 

 selves and the products of their mutual action remain free to react ? 

 Do they, according to a generally received opinion, remain unaltered, 

 or, should the affinities so preponderate, become simply AB and 

 CB ? Or do A and C, according to Berthollet's view, divide them- 

 selves in certain proportions between B and D, the said proportions 

 being determined not solely by the difference of energy in the affini- 

 ties, but also by the difference of the quantities of the bodies ? And, 

 supposing the latter to be the correct view, do the amounts of AD 

 and CB produced by the reaction, increase progressively with the 

 relative increase of AB, or do sudden transitions occur, such as 

 Bunsen and Debus have recently observed in certain cases where the 

 products were removed at once from the field of action ? 



A reply was sought in the colours produced upon mixing different 

 salts in aqueous solution. There were not many coloured salts suit- 

 able for the purpose, as it generally happens that a base gives the 

 same colour with whatever acid it is combined, and vice versd ; but 

 the compounds of sesquioxide of iron were peculiarly adapted to 



