Q 



PREFACE. 



THE reasons which induce me to gather together in 

 this Volume the various physical and chemical papers 

 scattered in the Philosophical Transactions and else- 

 where, are the same as those which caused the ' Experi- 

 mental Researches in Electricity ' to be collected into one 

 Series. As investigations, several of them are very 

 imperfect ; but it was thought a duty to print them just 

 as they were, that they might be referred to as safely for 

 facts, opinions, and dates, as the original papers. The 

 correction of certain phrases and typographical errors, 

 and the addition of some matter here and there with its 

 proper date, is not considered as interfering with this 

 intention. 



MICHAEL FARADAY. 



October, 1858. 



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