26 



Nova Acta Physico-Medica AcademicB Csesarese Leopoldino-Caro- 

 linffi Naturaj Curiosorum. Vols. X. XI. XII. XIII. XIV. and 

 XV. Part I. — From the Imperial Academy of Bonn. 



Transactions of the Linnean Society of London. Vol. XVI. Part III, 

 — From the Society. 



Treatise on Conic Sections, from the Encyclopaedia Britannica. By 

 Professor Wallace. — From the Author. 



Bulletin de la Societe Geologique de France. Tome III. Feuilles 

 I.— V. — From the Society. 



The following Communication was then read : — 



On the Composition of some Iron Slags. By J. F. W. 

 Johnston, Esq., F.R.S.E. 



This paper described the composition of some crystallized slags 

 from Birtley Iron-Works, in the County of Durham. These slags, 

 like those from Wales described by Professor Miller in the Cam- 

 bridge Transactions, had the form of the olivine, and in composition 

 were nearly pure silicate of iron, containing about 0*4 per cent, of 

 foreign matter, chiefly magnesia. The author also gave a short ac- 

 count of a method by which the magnet might be made available in 

 giving immediately very near approximations to the quantity of iron 

 contained in the basic silicates of iron. 



At the Birtley Iron- Works, the author stated that beautiful crys- 

 tals of titanium had likewise been found. 



Dr Knox made some verbal remarks on the Structure of the 

 Ribs. 



The Society then adjourned to the general meeting in 

 November. 



