xvi CONTENTS. 



fcn'ption of tlie common proce'^s for making fmall (hot ; and aTTo of the maniifjflurc of patent 

 Ihot. Experimcnls and remarks on the means of precipitating magnefia in the nioft light and 

 impalpable Rate. 



V. On the claftic Fluid coinaincJ in the Air-veflelsof Fifh — p. 264 



Oxygcnc found in tlie air-vctrcl of the fword-fifli. Azote in other fi(h. 



VI. Account of certain remarkable Changes of Colour and Direftion of the 

 Clouds during a Thunder Storm — • — — p. 265 



Circumftanccs attending the ftorm of July 30th, 1797. Inferences. 



VII. The Method of making excellent Bread without Yeaft; as p raft i fed at 

 Debretzin, in Hungary. By Robert Townfon, L.L.D. F.R.S. Edin. p. 2:7 



Account of a leaven which may be kept fix months. Method of ufing it. 



VIII. Defcription and Ufe of an Eudiometer, with Sulphuret of Potafli. By 

 Citizen Guyton — — — — p. 268 



The (lownefs and imperfeftion of S:lieelf 's procefs are removed by the application of heat. Very 

 limple eudiometer. 



IX. Defcription of an improved Eledlrometer, in which the Senfibility of the 

 Gold Leaf is confiderably augmented, and the Intenfities are diftinguiftied by 

 numerical Graduation — — — p. 270 



The elcftromctcr improved, by making the uninfulated fide-pieces adjuftablc. 



X. The improved Procefs of Tanning. By Citizen Seguin — P- 271 



Art of tanning. Lixiviations of tan. Tanning principle .ind gallic acid. Infoluble compound of 

 gebtin and tanin. Other interelling fafls : tanin becomes oxided. Strufture.and compofition of 

 (kin. Fibrous matter is oxygenated glue, and mud be difoxygenated before it will tan. Reafons 

 why the procefs ought to he gradual ; but the time may be a? Ihort as not to exceed a fortnight. 

 Important coufideralions refpcdling the new properties ftuffs acquire by tin£lorial procefles. 



XI. The Combuftion of Phofphorus in the Vacuum of the Aii'-Pump. By 

 Dr. Maninus Van Marum (Concluded from p. 237. J — p. 279 



Inflammation of phofphorus in vacuo, when wrapped in cotton powdered with rcfin. Analytical 

 experimentf, which (hew that the cotton clothing is chiefly concerned. Phenomena attending 

 thiscombunion. 



Mathematical Correfpondcnce — — — p. 283 



Queftion refpefting a glory feen in water. DiiEculty dated relative to the Fata Morgana. 



New Publications — — — — p. 285 



OCTOBER 



