LAB 



LAB 



a centre hole at the other; chiefly used 

 with a tangent line, to take altitudes. 



LABIAL letters, those pronounced 

 chiefly by means of the lips. See LET- 

 TER. 



LABIATED^owers, monopetalous flow- 

 ers, consisting of a narrow tube, with a 

 wide mouth, divided into two or more 

 lips. See BOTANY. 



LABORATORY. A laboratory, pro- 

 perly fitted up with apparatus, is essen- 

 tially necessary to a chemist whose ob- 

 jects lead him to make researches, expe- 

 riments, and processes, upon all the 

 different scales of operation. That great 

 interest which the important science of 

 chemistry has excited in all ranks of men, 

 within the last thirty years, has rendered 

 it easy to procure very complete sets of 

 apparatus ; which, at least in the metro- 

 polis, may be collected in a short time, by 

 tho.se who, like Boyle, Cavendish, Levoi- 

 sier, and other great men, are in posses- 

 sion of ample means. But on the other 

 hand, it is proper to remark, that many of 

 our greatest discoverers, such as Scheele, 

 Priestley, Berthollet, Wollaston, Dalton, 

 Crawford, and a numerous set of emi- 

 nent men, have from choice, or from mo- 

 tives of prudence, made use of very sim- 

 ple, cheap, and small sized apparatus. It 

 is undoubtedly true, that many operations 

 can only be performed upon a scale of 

 considerable magnitude, and that many 

 facts of great value display themselves 

 upon the extensive theatre of nature or in 

 large manufactories, which are either not 

 seen, or require uncommon discernment 

 to perceive them in the contracted space, 

 and during the short time employed in 

 the performance of a philosophical expe- 

 riment. But it is no less true, that expe- 

 riments upon a small scale do likewise 

 possess their exclusive advantages. Dur- 

 ing the fusion and combination of sub- 

 stances, in the whole no larger than a 

 pepper-corn, before the blow-pipe, the 

 effects take place with rapidity, and many 

 of them, such as the escape of gas by ef- 

 fervescence, the changes of colour, and 

 transparency by differences in the heat 

 applied, the manner of acquiring the solid 

 state, &c. which cannot be seen in the 

 furnace, are in the course of a few se- 

 conds remarked and ascertained. The 

 saving of time is also an object ot'leading 

 importance. The same considerations 

 are likewise applicable to processes of 

 fusion, or other applications of heat in a 

 small vessel, such as a tobacco-pipe, pla- 

 ced in a common fire, urged by the bel- 

 lows if necessary. Humid operations may 



alsolbe very advantageously conducted by 

 single drops of liquid, and small particles 

 of solid bodies laid upon a glass plate, or 

 in the metallic spoon, and the lamp for 

 distillations, and other works even upon 

 a scale of some magnitude, has long been 

 a favourite instrument with chemists. 

 These will come under our notice as we 

 proceed. 



Under our article CHEMISTRY we have 

 given a concise sketch or enumeration of 

 the practical treatment of bodies, which 

 leads us to point out the instruments in. 

 this place. 



For the mechanical division of bodies 

 it is requisite the chemist should have the 

 usual instruments for cutting, breaking, 

 rasping, filing, or shaving. One or more 

 mortars for pounding ; the best are made 

 of hard pottery. A stone and muller for 

 levigating. A pair of rollers for lamin- 

 ating metals. A forge for many or most 

 of the purposes in which the blast heat of 

 a small fire is required ; and various other 

 tools and implements, not peculiar to che- 

 mistry. 



Messrs. Aikin, in their Chemical Dic- 

 tionary, give the following list of imple- 

 ments and materials ; which, upon deli- 

 berate examination, we highly approve : 



A gazometer, with the connecting tubes, 

 blow-pipe, &c. 



A bladder, or silk bag, with stop cock, 

 fitting the above. 



A pneumatic water trough. 



A copper still with worm tuo, the still 

 fitting into the top of the Black's furnace. 



A blow-pipe, with spoon, &c. 



Lamps an Argand, and others of com- 

 mon construction, for oil and alcohol. 



An apparatus for drying precipitates by 

 steam. 



Scales and weights. 



Large and small iron stands for re- 

 torts, &c. 



Mortars one of hard steel, one of bell- 

 metal, and one or two of Wedgwood ware. 



A silver crucible and spatula. 



A platina crucible and spatula. 



A jointed iron tube for conveying gases. 



The folio-wing articles in glass .- 



Retorts of different sizes, plain and 

 stoppered, and long necked for guses. 



Receivers to fit the above, plain and 

 stoppered, with or without an adopter. 



Plain jars for gases, different sizes. 



Lipped jars for mixtures, precipitates, 

 &c. 



A graduated eudiometer jar. 



Bell receivers, two or three sizes. 



