ATTRACTION. 175 



instruments as will enable us to show facts ; they are for utility, and 

 not for mere parade, but in a public establishment, elegance may 

 be in a good degree, combined with utility. 



An apparatus is best explained, when it is used ; but a few facts 

 may be stated advantageously in this stage of our progress, and the 

 names of some leading instruments and operations may be given. 



A considerable number of instruments has already been mention- 

 ed, but they have been chiefly those which illustrate general princi- 

 ples, and the greater part have been very intelligible. For private re- 

 search, and for the instruction of only a lew persons at once, a compli- 

 cated and expensive apparatus is not necessary. Much may be done 

 by cheap and simple means. * Still, it is an error to suppose that re- 

 fined analysis and difficult researches that demand great precision, 

 can be accomplished without proper instruments, and various and 

 sometimes expensive reagents ; nor can full effect be given before a 

 large audience, to the fine experiments with which chemistry 

 abounds, without an apparatus, and materials corresponding in some 

 measure, to the splendor and dignity of the subject. 



For a full account of chemical apparatus and operations, the stu- 

 dent is referred to Mr. Faraday's excellent work on chemical mani- 

 pulations, where all the information that can be desired is given. 



Apparatus names of things heads and hints. Instruments of 

 chemistry, to be perfect, should be, 



(a.) Transparent. 



Ib.) Incapable of corrosion. 



(c.) Incapable of fracture by heat and cold. 



( d.) Strong to confine elastic vapors. 



(e.) Not liable to be melted or otherwise injured by heat. 



Glass, metal, and earthen ware, collectively possess these properties. 



Glass has the two first characters, in a sufficient degree, but not the 

 rest; 



Metal, has sufficiently the third an,d fourth, and 



Porcelain or earthen ware, the fifth, provided the heat is careful- 

 ly managed. 



1. Means of producing heat. 



(a.) Fuel, fyc. Charcoal, coak, anthracite and other coals ; wood, 

 oil, alcohol, ether, hydrogen gas ; this gas and oxygen ; friction, per- 

 cussion, fermentation, chemical mixtures. 



2. Instruments in which, and means by which the application is to 

 be made. 



* I heard Dr. Priestly say, that his principal instruments were gun barrels, glass 

 tubes, flasks, vials and corks, and it is well known that few men have made more 

 discoveries. Still he was a pioneer ; he was always on travels of discovery, and his 

 operations were not in general so remarkable for refinement, as for sagacity and 

 effect. 



