ir CONTENTS. 



AUGUST 1803. 



Engravings of the following Objects : 1 . An Apparatus for determining the 

 comparative Wear of Gold. By the Hon. H. Cavendifh, Eiq. j 2. Mr. 

 Henry's Apparatus for meafuring the Abibrption of Gafes j 3. A Subterra- 

 neous Graphometer, by M. Komarzewfki. 



I. On the Production of Sulphate of Magnefia from the Aflies of Pit-Coal, with 

 Remarks on the Efflorefcence of the fame Salt, obferved by Dr.Boftock. In a 

 Letter from the Rev. William Gregor. - 225 



II. The Method of making Artificial Yeaft in Germany and Sweden. Commu- 

 nicated by Sir A. N. Edelcrantz. 228 



HI. Remarkable Fact of the Difappearance of a Mixture of Oxigen and Hy- 

 drogen, at the common Temperature over Water j inducing the Probability 

 that Water may be formed at low Heats. In a Letter from Mr. B. Hooke. ib. 



IV. Experiments on the Quantity of Gafes abforbedby Water, at different Tem- 

 peratures, and under different PrefTures. By Mr. William Henry. 229 



V. Of the State of Vapour fubfifting in the Atmofphere. By Richard Kirwan, 

 Ei'q. LLD. F. R.S. and P. R.I. A. ... 2 42 



VI. Experiments and Gbfervations in Support of the Theory of Ventriloquifm 

 which is founded on the Reflection of Sound. In a Letter from Mr. John 

 Gough. - _..--- 247 



VII. Examination of the fo called Salt of Bitumen, the Bit-Nobin of the Hin- 

 doos. By Frederick Accum, Practical Chemift and Teacher of Che- 

 miftry. - - - - - - - 251 



VIII. Experiments on the Invifible Rays of the Solar Speclrum. By M. Rit- 

 ter, of Jena. Communicated by M. Vicktred, Doctor in the Univerfity of 

 Copenhagen, to the Editors of the Bulletin des Sciences at Paris, No. 73. 255 



IX. An Account of fome Experiments and Observations on the ConfKtuent 

 Parts of certain Aftringent Vegetables; and on their Opeiation in Tanning. 

 By Humphry Davy, Ei'q. Profeflbr of Chemiftry in the Royal lnftitution. 256 



X. Memoir on the Nature and the new Properties of the Pruific Acid. By 

 Cit. Curaudau, correfponding Member of La Societe libre des Pharmaciens 

 de Paris. _.----. 277 



XI. Defcription of the Subterraneous Graphometer invented by M. Komar- 

 zewfki, F. R. S. and prefented to &e National Inftitute of France. 283 



XII. Experiments and Observations on the various Alloys, on the Specific Gra- 

 vity, and on the comparative Wear of Gold. Abftracled from the Memoir of 

 Charles Hatchett, Efq. F. R.S. ----- 285 



XIII. Obfervations of the Tranfit of Mercury over the Difk of the Sunj to 

 which is addtd, an Investigation of the Caufes which often prevent the proper 

 Action of Mirrors. By William Herfchell, LL.D. F. R, S. - 304 



