Mr. Faraday on Chemical Manipulation, 277 



as often happens, the facility of working with small quantities 

 is also of much importance, as otherwise the opportunity of 

 gaining information may be lost, or only retained at great 

 expense. ** There existed," says our author, ** in the British 

 Museum a small fragment of a black stone, the source and 

 history of which was unknown : it was unique, no other spe- 

 cimen being in the Museum, or known to be in existence ; yet 

 as it presented some jieculiar characters, Mr. Hatchett Xvas 

 induced to examine it, and, working with a portion of the stone 

 weighing not more than two hundred grains, he was enabled 

 to discover in it a new metal, which he distinguished, by its 

 various characters, from aK those previously known, and 

 which he named Columbium. Ekeberg afterwards disco- 

 vered a metal, which he named Tantalium, conceiving it to 

 have been observed and distinguished for the first time by 

 himself; but Dr. Wollaston, who examined it, and compared 

 it with columbium, was able to identify it with that metal, 

 although he had not more than five grains of the stone from 

 the British Museum upon which to make his experiments." 



In short, there can be but one opinion respecting the first- 

 rate importance of expertness in manipulation, and neatness, 

 dexterity, and efficacy of experimenting. These are the sub- 

 jects to which the present volume is directed, and which will, 

 therefore, form a valuable accompaniment to the more gene- 

 ral and systematic works. They .are discussed under the 

 following general heads :-4f(o hih-v) >.■■' 



The conveniences and requisites of a laboratory/. 

 Chemical apparlitus^ and its uses. 

 The methods of performing chemical operations. 

 The facilities acquired by practice ; and, 

 . The causes which make eocperiments fail or succeed. 



The description of a laboratory is followed by two long 

 and well-written sections on the arts of weighing and mea- 

 suring, in which the account of the methods of determining 

 specific gravities, and of the general management of a delicate 

 balance, are well deserving the student's attentive perusal : 

 indeed, there are no operations which are more frequently per- 

 formed in a slovenly and careless manner, than those in which 

 scales and weights are concerned ; and we should advise the 

 tyro to sit down with his balance and this book before him, 

 and practise the manipulations which it explains. 



The fourth section, on the sources and management of heat, 

 is devoted to the construction and management of diflferent 

 kinds of furnaces, lamps, blowpipes, thermometers, and py- 

 rometers, and abounds in useful hints, and in the details of 



