CONTENTS. 



PAGE 



I. Researches on the Complex Inorganic Acids. By Wolcott 



Gibbs, M.D 1 



II. A New Form of Plethy sinograph. By II. P. Bowditcii, M.D. 22 



III. Botanical Contributions. By Asa Gray 25 



IV. On the Estimation of Phosphoric Acid as Magnetic Pyrophos- 



phate. By F. A. Gooch 53 



V. On the Mechanical Equivalent of Heat, with Subsidiary Researches 

 on the Variation of the Mercurial from the Air Thermometer, 

 and on the Variation of tfie Specific Heat of Water. 15 v 

 Henry A. Rowland 75 



VI. Propositions in Cosmical Physics. By Benjamin Peirce . 201 



VII. Researches on the Substituted Benzyl Compounds. Sixth 



Paper. By C. Loring Jackson and A. W. Field . 202 



VIII. Researches on the Substituted Benzyl Compounds. Seventh 



Paper. By C. Loring Jackson and J. Fleming White 213 



IX, Contributions from the Physical Laboratory of Harvard 

 College : — 



16. A New Me/hod of Studying Ware Motions. By II. II. 



ErsTis 218 



17. Vibrations of Circular and Ellipitical Plates. By 



Francis E. Cabot 219 



18. Perforated Vibrating Discs. By Fkancis E. Cabot . 2l'2 



19. On a Standard for Estimating the A mom it of Light 



Reflected by Various Substances. By A. II. Lee . 223 



20. Effect of Distance on Appreciation of Color. Br VV. H. 



Schwartz 229 



21. Simple Apparatus for Illustrating Periodic Motion. By 



John Trowbridge 232 



22. Illustration of the Conservation of Energy. By John 



Trowbridge _':j> 



