Miscellanies. 345 



It is strictly logical, to place these three bodies and oxygen togeth- 

 er, and of course, at the beginning ; because, in the chemistry of 

 particular bodies, we cannot move a step without oxygen ; and hap- 

 pily, the illustration of its powers and general relations, is equally 

 easy and delightful, both to the teacher and to his uninstructed pu- 

 pil. But if, at this period, we proceed immediately to chlorine, io- 

 dine and bromine, both teacher and pupil are at once embarrassed, 

 by properties and relations which the one cannot understand, and the 

 other cannot explain.* Nor is there any sufficient advantage, to 

 compensate for this embarrassment ; for, we can dispense with the 

 mention of either of these three bodies, and especially of the last two, 

 until we are much further advanced, and have become rich in facts 

 and principles, and expert in reasoning upon them. Then, after the 

 combustibles, and before the metals, these other bodies may be in- 

 troduced, with the happiest preparation ; we easily and naturally re- 

 vert, and explain their relation to the combustibles, and then we 

 can also, with equal ease, illustrate their affinity to oxygen. 



Thus far then, the course now sketched, would seem to be eligi- 

 ble ; — that is to say, oxygen being placed first, and the simple non-me- 

 tallic combustibles, next ', the mutual relations of these furnish some 

 of the most important acids j and when chlorine, iodine and bromine 

 follow, and their relations are extended back to the preceding bod- 

 ies, then several other acids, and compounds, of great interest and 

 importance, are brought forward with advantage. 



But, the greatest practical difficulty in making an arrangement, 

 which shall be both intelligible and profitable to the pupil, still re- 

 mains to be stated. The discovery of the metallic bases of the fixed 

 alkalies and earths, by which it is proved that those bodies are oxides, 

 leaves them to fall, by a natural method, into the train of the metals. 

 If then, we sacrifice every thing else, to a method the most rigorously 

 logical, we must break up the ancient and highly important classes of 

 alkalies and earths ; the account of them, as of isolated bodies, we 

 must place, late in the course, or in the book, in the train of the met- 



* I am sensible, that writers of the greatest respectability pursue the course which 

 is here objected to : in a work, intended for the learned in the science, or even for 

 those who have a general knowledge of it, this is not of great consequence, because 

 the anticipated relations are, in a greater or less degree, familiar. I would by no 

 means be understood to censure such writers. My remarks have reference to 

 works and courses of instruction, intended for pupils, to whom even the first ele- 

 ments are, as yet, unknown. 



