Ber/xliub on the Uae of the BlovJ-plpc. 325 



the author, very truly, in his iutioduction, " is highly interest- 

 ing to the practical chemist, the miner and the mineralogist. It 

 is a system of chemical experiments, made in the dry way, as it 

 is called, and almost always on a miscroscopic scale, but which 

 presents us in an instant with a decisive result." It is not less 

 true, that the way in which he has treated it, is as satisfactory 

 as the subject is important. Mr. Children (whose translation 

 we shall more particularly notice hereafter, adopting it generally 

 in the mean time, in the passages we may have occasion to 

 quote) observes in his preface, " The name of Berzelius, as a 

 skilful and patient experimenter, stands almost unrivalled ; and 

 the present essay amply vindicates his claim to the high reputa- 

 tion he has acquired. It is an invaluable collection of import- 

 ant and new facts, and admirably supplies ihe want which has 

 long been felt and acknowledged of a scientific practical treatise 

 on the blow-pipe." (Trans, preface, v.) The observation is 

 just in every respect. 



The subject is treated in the following order. History of the 

 blow-pipe. — Description of the blow-pipe. — The combustible— 

 the blast and flame — the support — additional instruments — 

 the re-agents and their use — the habits of the pure alkalies, 

 earths, metallic oxides, sulphurets, alloys and acids, before the 

 blow-pipe, and the pyrognostic characters of minerals and 

 urinary calculi. 



Lamps are recommended to be used with the blow-pipe, in 

 preference to candles, as " the radiant heat from the substance 

 under examination melts the tallow or wax, and occasions them 

 to burn away too fast ; and besides commoti candles do not al- 

 ways furnish sufficient heat." " The best fuel for the lamp is 

 olive oil." 



Under the head " blast and Jiame,'" are given very ample 

 and accurate directions how to keep up a steady blast, and pro- 

 duce a strong heat, and the following instructions for oxidation 

 and reduction are very important. 



" Oxidation ensues when we heat the subject under trial be- 

 fore the extreme point of the flame, where all the combustible 

 particles are soon saturated with oxygen ; the farther we recede 

 from the flame, the better the oxidation is effected (provided we 

 can keep up sufficient heat;) too great a heat often produces a 

 contrary effect, especially when the assay is supported by char- 

 coal. Oxidation goes on most actively at an incipient red heat. 

 The opening in the beak of the blow-pipe must be larger for this 

 kind of operation than in other cases. 



" For reduction, a fine beak must be employed, and it must 

 not be inserted too far into the flame of the lamp ; by this means 

 we obtain a more brilliant flame, the result of an imperfect com- 

 busiion, whose particles, as yet unconsumcd, carry off the oxy- 

 gen from the subject of experiment, which may be considered as 



