It 



CONTENTS. 



Ancient defcription of Scylla and Charybdis compared with their prefent flate. Caufes why Scylla 

 is dangerous to mariners. Inftance. Situation of Charybdis, ufually fuppofed to be a whirlpool. 

 An excurfion to the fpot. Miftake of Homer with regard to the fituation and nature of this phe- 

 nomenon. Modern improvements in fhip-biiilding and navigation have rendered Scylla and 

 Charybdis lefs dangerous. 



V. Inftru£lions for refining Saltpetre by a new Procefs. By J. A. Chaptal, 

 J. P. Champy, and Bonjour — — — — P- 23 



reticular direftions for refining crude faltpetre — by percolation — folution in boiling water — cryf- 

 ' tallization by cooling with agitation — waftiing, draining, and drying. Great expedition, cheap- 

 nefs, and excellence of this method. Examination of other proceilies. 



VI. On the Light emitted by fuperfaturated Borate of Soda, or common 

 BoraXj By Mr. F. Accum — — — p. 28. ' 



Borax, when ftruck, emits an uncommonly white flafli. 



VII. New Conftruftion of the Air-pump. By Sir George S. Mackenzie, 

 Bart. — — — — — il>. 



Air-pump with a folid pifton, both valves in the bottom of the barrel, and the valve from the re- 

 ceiver opened mechanically. Limits of effeA in this pump, and alfo in thofe of Cuthbertfon, 

 Prince, W. N. and Sadler. 



VIII. On the A£tion of Nitre upon Gold and Platina. By Smithfon Tennant, 

 Efq. F.R.S. — — ■— — p. JO 



Gold is diflblved in nitre by ftrong heat, and rendered partly foluble in water. When this metal 

 is diflblved in alkali, it is thrown down in the metallic flate by nitre or nitrous acid, provided 

 thefe be partly deprived of oxygen. Platina is alfo foluble in ignited nitre, and rendered partly 

 foluble in water. Silver is fcarcely afted upon by nitre. 



IX. An Account of the Caufes of Alteration injurious to the Quality of Corn, 

 and the Means of preventing this Change. By B. G. Sage, of the ci-devant 

 Academy of Sciences, Profeffor of Chemiftry and Mineralogy in the School 

 des Mines de la Monnoie — - — — — P-^3^ 



When corn is houfed without fufficient drying, it heats, ferments, and the elaftic gluten is no longer 

 found; at the fame time that it lofes its vegetative and nutritive powers. 



X. Defcription of an Apparatus for difengaging Oxygen Gas, and applying 

 it to the bed Advantage. Conftrufted by James Sadler, Efq. Chemift to 

 the Admiralty. To wbich are added, Obfervations upon the Blow-pipe. 

 ByW. N. — — — — — p. 33 



Simple furnace for extricating oxygen, and for other general experiments. Apparatus for heating 

 the ftream of oxygen when ufed. Experiments on the denfity and velocity of air from the com- 

 mon blow-pipe. Dedudion of the fize of bellows required to produce the fame effeift. Obfer- 

 vations on the air-veffel of fire-engines, tending to fhow in what circumftances it may be ap- 

 plied to blowing engines. 



XI, A 



