CONTENTS. Vn 



Page. 



il. Chemistry. — Mineralogy. 



Adam van deb Toorn's Table of the Proportions of anhydrous acid 

 in acetic acid of every degree of concentration between pure 

 water and the hydrated acetic acid, compared with the specific 

 gravities, water at 59° Fahr. being taken as unity 571 



Robert W. Fox's Account of some Experiments on the Electricity 

 of the Copper Vein in Huel Jewel Mine 572 



Sir David Brewster's Notice respecting a remarkable Specimen 

 of Amber 574 



Sir David Brewster's Remarks on the value of Optical Characters 

 in the discrimination of Mineral Species 575 



The Rev. William Vernon Harcourt's Experiments on the ef- 

 fects of long-continued Heat on Mineral and Organic Substances 576 



Dr. Clark's Explanation of the Successful Application of the Hot 

 Blast to the Production of Cast Iron 578 



Professor Graham on hydrated Salts and metallic Peroxides ; 

 with Observations on the doctrine of Isomerism 579 



George Lowe on some new Chemical products obtained in the 

 Gas-works of the Metropolis 582 



Henry Hough Watson on the quantity of Carbonic Acid in the 

 Atmosphere • • • ^^^ 



J. F. W. Johnston on the Chemical Composition of crystallized 

 Oxichloride of Antimony 587 



Charles J. B. Williams on the phaenomena and products of a 

 low form of Combustion 588 



Dr. Wm. Gregory's Abstract of the Discoveries made by Dr. 

 Reichenbach, in his examination of the products of destructive 

 Distillation 591 



III. MAtHEMATlCAt INSTRUMENTS AND MECHANICAL ArTS. 



Professor Forbes on a new Sympiesometer 593 



David Dick on the construction of Achromatic Object-Glasses . . 59S 

 John Dunn on a new Klinometer and portable Surveying Instru- 

 ment 594 



E. J. Dent on a Chronometer with a Glass Balance-spring .... 595 



Mr. Gordon on the Polyzonal Lens 595 



Mr. Rennie on an Instrument for taking up Water at great depths 595 

 Professor Stevelly on the application of a Vernier to a Scale, not 

 of equal but of variable parts, and particularly to WoUaston's 

 Scale of Chemical Equivalents 596 



IV. Natural History, Anatomy, and Physiology. 



Botany. 

 Robert Brown on the plurality and development of Embryos in 

 the Seeds of Coniferce 596 



