1826.] of the British System of Chemical Instruction, 373 



His memory is aided as much by their classification into metals, 

 earths, gases, combustibles, acids, alkalies, &c. as that of the 

 botanist is by the Linnaean arrangement of plants ; and though 

 both are in some respects artificial, yet both are decidedly 

 useful. In fact, the comparative ease with which the sciences 

 are studied in latter years arises from this facility of arrange- 

 ment, which enables the student to refer many hundred (in some 

 cases many thousand) individuals to a very few classes ; each 

 possessed of a common character or family likeness. In che- 

 mistry, unfortunately, the electro-positive and negative clas- 

 sification (though scientifically correct,) requires so much pre- 

 vious knowledge for its proper comprehension, that a pupil is 

 altogether debarred from its aid in making his first experimental 

 acquaintance with the science. It would, therefore, perhaps be 

 as well not to press it on his attention, till he had learned suffi- 

 cient to fully understand and appreciate it. 



A junior class cannot see too much of the practical opera- 

 tions of the laboratory as soon as it can comprehend them. 

 Whenever the preparation of a substance will not distract atten- 

 tion from the lecturer, as he proceeds to new matter, and 

 whenever his time permits, it will be wise to bring his furnaces 

 before his pupils, and convert the mysteries of the laboratory 

 into engaging illustrations, and welcome aids to memory. 



In the instruction of this junior class, a lecturer^s object 

 should not be to teach all that is known of the science, but to 

 lay a solid foundation of general facts in the youthful mind, and 

 create in it an ability and a desire to work out its own instruc- 

 tion, while he unfolds the means, and gradually implants in it 

 the habit of industrious investigation. 



Proceeding in this spirit, he will not dwell on the minor salts 

 of the vegetable, animal, and mineral world, unless he can asso- 

 ciate them with some agricultural, mining, physiological, or 

 medical comments, which are always valuable as practical illus- 

 trations of the use of chemistry. The merits of rival hypo- 

 theses (or unproved theories) are matters interesting only to 

 more advanced students, and may safely be omitted for the pre- 

 sent, I am also of opinion, that, however consistent it may be 

 to commence an advanced course with separate lectures devoted 

 to the explanation of the laws of chemical action, and what are 

 termed the canons of chemistry, — yet they may with great pro- 

 priety be omitted in an elementary one, inasmuch as a pupil 

 cannot then apply them : he may remember them by great ex- 

 ertion, but such knowledge hangs a dead weight on his memory 

 till he is aflforded an opportunity of deducing them from his own 

 practice, or from observations on the experiments exhibited at 

 lectures. A great evil is done when the mind of a youth is 

 bewildered by having more information pressed upon him than 

 he can receive at once* Confusion induces despondency, and 



