380 Royal Society : — 



natron lakes of Hungary and Egypt, to produce deposits of magne- 

 sian carbonate. 



The conditions of these deposits at Pointe-Levis and elsewhere in 

 the Quebec group, seem to point to the existence of basins along an 

 ancient sea-shore, which probably marked the first upheaval of the 

 older Silurian strata. Beds of travertine were there formed, and 

 then the sea flowed over these deposits and gave rise to the fossili- 

 ferous limestones ; but there were intervals of disturbance, indicated 

 by the conglomerates, and these movements, or the deposition of bars 

 along the shore, gave rise to lagoons or basins cut off from the sea, 

 where, by evaporation under the conditions which we have supposed, 

 magnesian precipitates would be deposited. The absence of fossils 

 in these beds is probably connected with the peculiar composition of 

 the waters. 



"A Fourth Memoir upon Quantics." By Arthur Cayley, Esq., 

 F.R.S. 



"A Fifth Memoir upon Quantics." By Arthur Cayley, Esq., F.R.S. 



" On the Tangential of a Cubic." By Arthur Cayley, Esq., F.B.S. 



"On the Constitution of the Essential Oil of Rue." By C. Gre- 

 ville WilUams, Esq., Lecturer on Chemistry in the Normal College, 

 Swansea. 



The essential oil of rue and its products of decomposition have 

 been examined by several chemists. Will analysed it many years ago, 

 and deduced theformula C"^ H=^ O^ as the result of his analyses. The 

 principal investigation of it was made by Gerhardt, who regarded it 

 as the aldehyde of capric acid. The production of capric acid from 

 it by the action of nitric acid, as observed by Gerhardt and also by 

 Cahours, has been considered as corroborative of the 20 carbon for- 

 mula. It is evident, however, that the formation of capric acid 

 merely indicates the aldehyde to contain not less than 20 equivalents 

 of carbon. 



Some experiments made with a view to the production of certain 

 new derivatives of capric aldehyde, led the author to believe the ideas 

 generally entertained regarding the formula of the oil to be erroneous. 

 Before continuing his experiments, he has therefore reinvestigated the 

 nature of the oil itself. 



In order to obtain the aldehyde in a state of purity, advantage was 

 taken of the tendency of the aldehydes to combine with the alkaline 

 bisulphites. The oil obtained from the ammoniacal bisulphite of the 

 aldehyde was carefully analysed. The mean of eight very coincident 

 analyses gave, — 



Mean. Calculation. 



Carbon 7771 C" 132 77-65 



Hydrogen .. 13-07 H" 22 12-94 



Oxygen 9-22 0' J16 9-41 



100-00 170 100-00 



