CONTENTS OF VOL. XXI. 



NUMBER CXXXV.— JULY, 1842. 



Page 



Prof. D. P. Gardner on the Influence of the Dew-point on Ve- 

 getables, considered especially with reference to their Tem- 

 perature 1 



Messrs. W. Francis and H. Croft's Notices of the Results of 



the Labours of Continental Chemists (continued) 15 



Mr. Galloway's Further Remarks on Fernel's Measure of a 

 Degree, in Reply to Professor De Morgan's Letter in the 



Number for May 22 



The Rev. D. Williams's Supplementary Notes on the true Posi- 

 tion in the " Devonian System " of the Cornish Killas .... 25 



The Rev. P. Kelland's Note on Fluid Motion 29 



Prof. Dove's Experiments in Magneto -Electricity, illustrative 



of a Passage in Professor Faraday's Researches 33 



Dr. R. Kane's Note on the Composition of the Basic Sulphate 



of Mercury, or Turpeth Mineral 35 



Mr. T. S. Davies on Pascal's Mystic Hexagram 37 



Mr. W. H. Balmain's New Process for Preparing Oxygen. ... 42 

 Mr. S. M. Drach on Sir D. Brewster's Deductions from the 



Hourly Observations at Leith in 1824-25 43 



Mr. Earnshaw on the Motion of Luminous Waves in an Elastic 

 Medium, consisting of a system of detached particles, sepa- 

 rated by finite intervals 46 



Proceedings of the Royal Society 50 



1» Royal Astronomical Society 56 



London Electrical Society 61 



Royal Irish Academy 64 



New Books : — Howard's Cycle of Eighteen Years in the Seasons 



of Britain 69 



On the Red Molybdate of Lead, by If. G. Rose 73 



Method of distinguishing between weak Solutions of Nitrates 



and Chlorates, by M. Vogel, jun 74 



On the Existence of Sulphur in Plants 74 



Action of Salts on Living Plants 76 



On Chlorite and Repidolite, by M. Kobell 76 



Analysis of theTachylyte of Vogelsgebirge, by M. Klett .... 77 



Analysis of Native Aluminates 78 



Meteorological Observations for May 1842 79 



Meteorological Observations made at the Apartments of the 

 Royal Society by the Assistant Secretary, Mr. Roberton ; 

 by Mr. Thompson at the Garden of the Horticultural Society 

 at Chiswick, near London; by Mr. Veall at Boston; by the 

 Rev. W. Dunbar at Applegarth Manse, Dumfries-shire ; and 

 by the Rev. C. Clouston at Sandwick Manse, Orkney .... 80 



a 2 



