CONTENTS. xix 



with a Defcrlption of the Apparatus for thefe Experiments. By George 

 Pearfon, M.D. F.R.S. (Concluded from p. 305) — p. 24<) 



Obfervatlons and inferences concerning the effeA of eleftn'city on wnter, in the experiments recited ; 

 and the general dodrines of chemiftry which they tend to explain. 



IV. Obfervations on the Eledrophore, tending to explain the Means by which 

 the Torpedo, and other Fifh, communicate the eleftric Shock p. 335 



A6lion of the eleclrophore. Experiments with ele&rophores of talc. — Compntations. — Figure and 

 dimenfions of the electric organs of the Torpedo. lndu6iion of their capacity or charge. Fatts, 

 which Shew that a mechanical Torpedo might be made, capable of giving innumerable fhocks, and 

 retaining its power for an unlimited time. Conjefturcs on the a£lual means of operation in the 

 Torpedo. 



V. A Letter from Mr. Von Humboldt, to Mr. H. Van Mons, on the chemical 

 Procefs of Vitality ; together with the Extraft of a Letter from Citizen 

 Fourcroy, to Citizen Van Mons, on the fame Subjeft — P- 359 



Experiments on theefFefts of chemical agents upon the irritability of the limbs of animals. — Cautioa 

 of Citizen Fourcroy againll multiplying hypothefes. 



VI. Concerning the Properties of the Sulphureous Acid, and its Combinations 

 with Eirthy and Alkaline Bafes. By Citizens Fourcroy and Vauquelin 

 (Concluded from p. 318.) — — — — P- 3^4 



Habitudes of the fulphates of foda, of ammoniac, of magnefia, of barytes, and of alumina. 



Vn. An Account of the Great Copper- Works in the Ifle of Anglefey. By 

 Mr. Arthur Aikin — — — — P- 3^7 



Account of the mines. They are for the mod part open quarries. Nature of the ores ; working 

 proceffes ; number of men employed. Port and town of Amlwch. Afpeft of the fliore. Villagc 

 of Cemmaes ; eftimable manners of the inhabitants. 



VIII. A Method of difpofing Gunter's Line of Numbers, by which the 

 Divifionsare enlarged, and other Advantages obtained — p. 372 



Theorems. Conllruftion of a Gunter's line, in which the divifions are enlarged eight times.— 

 Conflruftion of a fpiral logarithmic line, feven inches in diameter, but of equal power to that of 

 a Gunter's rule 40 feet long. 



IX. On the mechanical Projeifts for affording a perpetual Motion p. 375 



What is a perpetual motion ? Projefts of Biihop Wilkins — of the Marquis of Worceller^ 

 of Orfyreus — of Dr. Shiviers. Confidevations on the caufes of thefe deceptions. Inftrument of 

 Defagulitrs, and of the author, to (hew the fallacy of the notion from which projtiSors of fuch 

 fchemes rcafon. EflTcntial rcquifite to a perpetual motion. Enumeration of fuch natural agcntt 

 as may keep a machine in motion, as long as it retains its form, or till it is worn out. 



X. Ufeful Notices refpeding various Objeds— Silver alloyed with crude 

 Platina — Tempering of Steel — Rifled Shot — — p. 380 



Attempt to unite filver and platina. Sudden incrcafe of ignition at the inftant of congealing. On 

 the hardnefs and tenacity of fteel. Tempering by the colour ; — by blazing ;— and by oil. Rifled 

 fliot. Experiments which (hew that they revolve, but do move with more precifion than round (hot. 



Mathematical Corrcfpondence — — — P- 383 



7 DECEMBER 



