CONTENTS. J ■ xr 



VIII. Obfervadon of the Paflage of a Comet over the Difc of the Sun. By Citi- 

 zen Dangos — — — — P* 357 



Time and duration of the phenomenon. Inferences^ Why comets cannot be often fcen on the face of 

 the fun, 



IX. Analyfis of the Aqua-marine or Beryl ; and the Dlfcovery of a new Earth in 

 that Stone. Read before the French National Inftitute 26 Pluviofc, in the 

 Year VI. (Feb. 14, 1798.) By Citizen Vauquelin — P 35^ 



Method of Analyfis. New earth, foluble in acids and in pure potafh; and affording falts of a 

 faccharine tafte. Comparativi^ examination of its habitudes, and thofe of aiuminCj from which, 

 as well as the other earths, it greatly, differs. 



X. Defcription of a new-invented detached £fcapement for Pocket W^atches, Sec. 

 By Mr. John Prior — — — P- 3^3. 



XI. On Mr. Cartwright's Invention for rendering the Piftons of Steam Engines, 

 Pumps, and other Hydraulic Apparatus, tight by Metallic Parts, without pack- 

 ing or leathering. (W.N.) — — — P- 364 



Letter of enquiry. Defcription of the invention. Theoretic and pradical reafons why this con- 

 trivance muft prove lefs effcftual than the nnethods already in ufe. 



XII. Information refpedling the Zoonic Acid, difcovered by BertKollet p. 2^9 



Animal fubftances, the vegetable gluten^ and yeafl, afford an acid of deftruftive diftillation, which 

 may be faturated with lime, and the ammoniac then driven off by boiling. By the addition of 

 phofphoric acid, and diflillation at the boiling heat, the lime will form a phafphate, and the new- 

 acid will come over. Its charafters. 



XIII. Hiftorical Notes concerning the Invention of the Air-pump with Metallic 

 Valves ; the Neceffity of Alkali to produce the cryftallized Salt called Alum; 

 and the Eleftrical Inftrument called the Revolving Doubkr — p. 370 



XIV. Defcription of an Apparatus for faturating Potafh and Soda with Carbonic 

 Acid. By Cit. Welther — — — p. 371. 



XV. Abftraft of a Memoir of Klaproth on a new Metal denominated Tellurium. 

 Read at the Public Se/fionof the Academy of Sciences at Berlin. Jan. 25, 1798 



374 

 Hiftory of the difcovery. The white ore of gold is heated with muriatic acid ; to which the 

 nitric is afterwards added. The complete fohuion is diluted, and pure potafh is added in excefs. A 

 fmall portion of iron, together with gold, fallsdown; the reft is diffolved by the alkali. Muriatic 

 acid throws down a white precipitate. It is the oxyde of tellurium, and is reducible by being . 

 made into a pafle with oil, and fubjefted to a gradual heat. The metal rifes in diftillation like 

 mercury. It is white, fhining, brittle, friable, very fufible, combuftible with flame, combinable 

 with mercury, and with fulphur, foluble in acids, and in the. excefs of any alkali ; not pre- 

 cipitable by pruffiate of potafh, &c. &c. 



Scientific News, and Accounts of Books — — — P* 37^ 



American Societies. Aeroftation. Rumford's Effays. Rivard oa the Spherfr and Calendar, 

 Townfon's Mineralogy. Mr. Parke's Travels ia Africa, ^ „ , 



' D E C E M- 



