CONTENTS {continued). 



January 23, 1879. 



PAGE 



I. Researches on Chemical Equivalence. Part I. Sodic and Potassic Sul- 

 phates. By Edmund J. Mills, D.Sc., F.E.S., " Young" Professor of 

 Technical Chemistry in Anderson's College, Glasgow, and T. XJ. 



Walton, B.Sc . . .268 



II. Researches on Chemical Equivalence. Part II. Hydric Chloride and 



Siilphate. By Edmund J. Milis, D.Sc, F.R.S., and James Hogarth 270 



III. Researches on Lactin. By Edmund J. Mills, D.Sc, E.R.S., " Young " 

 Professor of Technical Chemistry in Anderson's College, Glasgow, and 

 James Hogarth . ' • • 273 



IV. On the Microrheometer. By J. B. Hannay, E.R.S.E., E.C.S., lately 



Assistant Lecturer on Chemistry in Owens College, Manchester . .279 



V. Limestone as an Index of Geological Time. By T. Mellard Reade, 



C.E., E.G.S., F.R.I.B.A 281 



YI. Prehminary Note on the Substances which produce the Chronio spheric 



Lines. By J. Norman Lockyer, F.R.S 283 



January 30, 1879. 



I. On the Effect of Heat on the Di-iodide of Mercury, Hgl 2 . By G. E. 

 Rodwell, Science Master, and H. M. Elder, a Pupil, in Marlborough 

 College . . . . 284 



II. A Comparison of the Variations of the Diurnal Range of Magnetic 

 Declination as recorded at the Observatories of Kew and Trevandrum. 

 By Balfour Stewart, E.R.S., Professor of Natural Philosophy in 

 Owens College, Manchester, and Morisabro Hiraoka . . . 288 



III. On the Determination of the Rate of Vibration of Tuning Forks. By 



Herbert McLeod, E.C.S., and George Sydenham Clarke, 

 Lieut. R.E 291 



IV. On certain means of Measuring and Regulating Electric Currents. By 



C. William Siemens, D.C.L., F.R.S. (Plates 4, 5) . . . . 292 



List of Presents . . . . .297 



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