CONTENTS. iii 



MAY 1800. / 



Kngravings of the following Objefits: 1. Figure illuftrating the Produftion of 

 Dewi and, 2. The Mechanical Doubler. 



I. On the different Effects of the Alcalis in the Produftion of Alum. By 

 Profeffor Hildebrandt, of Erlangen. - - ''- p. 49 



II. Experiments on Whinftone and Lava. By Sir James Hall, Bart. F. R. S. 

 &F.A.S. Edin. - - - - - p. 56 



III. A Memoir on the Difcovery of certain Bones of a Quadruped of the 

 Clawed Kind in the Weftern Parts of Virginia. By Thomas Jefferfon, Efq. 

 (Concluded from p. 43.) - - - - p. 66 



IV. Letter from Mr. John Heckewelder to Dr. Barton, giving fome Account 

 of the remarkable Inftinft of a Bird, called the Nine-Killer, - p. 73 



V. Letter from Dr. Beddoes on the Experiments made at the Royal Inftitution 

 with the Nitrous Oxide." - - - - p. 75 



J 



VI. On the colouring Matter of Dog's Mercury,' (Mercurialis perennis, Lin.) 

 By a Correfpondent. - -- - -. p. 76 



VII. Account of a Work entitled — " The Obfervations of Newton concerning 

 the Infleftions of Light ; accompanied by other Obfervations differing from 

 his ; and appearing to lead to a Change of his Theory of Light and Colours." 

 By a Correfpondent. - - - - p. 78 



VIII. Singular Inftance of Fecundity. In a Letter from the Rev. W. Pearfon, 

 of Lincoln - - - - - p. 85 



IX. On the Phenomena of the Morning and Evening Dew. By C. A. Prieur. 



p. 86 



X. Thoughts on Magnetifm. By Richard Kirwan, Efq. LL. D, F. R, S. 

 andM.R.LA. p. 90 



XI. Defcription of the Revolving Doubler. - - p. 95 



b 2 • JUNE. 



