in manipulation, a considerable advantage is gained, independent of that resulting from an acquaintance with the principles of the science; and this is so considerable, that, of two persons of equal talent and information in other respects, he who is the best manipulator will soon be in advance of the other; the one will draw just inferences with accuracy and rapidity, while the other will be lost in doubt, and often led into error. Mr. Faraday has pointed out several other cases of prominent advantage, arising from skilful manipulation, especially when very small quantities of matter are to be operated upon, and where accurate conclusions are of more than ordinary importance, as in testing for arsenic and other poisons on judicial occasions. When the substance under examination is rare, [p277] 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 specimen being in the Museum, or known to be in existence; yet as it presented some peculiar characters, Mr. Hatchett was 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 all those previously known, and which he named Columbium. Ekeberg afterwards discovered 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 subjects to which the present volume is directed, and which will, therefore, form a valuable accompaniment to the more general and systematic works. They are discussed under the following general heads:— _The conveniences and requisites of a laboratory_. _Chemical apparatus, and its uses_. _The methods of performing chemical operations_. _The facilities acquired by practice; and,_ _The causes which make experiments fail or succeed_.