On Mineralogy. 1 27 



were. 4. Gaseous metal, azote. These, which constitute 

 the principal part of terrestrial beiixgs, Dr. Mitchill con- 

 sidered under tour memorable points of view. First, in 

 connection with sulphur, forming o;-e5; secondly, with oxy- 

 gen, makipg oxides and acids; thirdly, with phlogiston, or 

 hydrogen, constituting what are properly denominated me- 

 tals ; and fourthlv, combinations with each other, com- 

 posing glass, porcelain, earthenware, the other prodigious 

 mass oi alloys and amalgams, or metallic mixtures. 



II. — Bodies abounding in intlammable and phlogistic 

 matter. 



Under this section are placed as well the sulphuric, phos- 

 phoric, and carbonic, as the hydrogenous compounds. Ac- 

 cordingly sulphur, inflammable air, coal of many kinds, all 

 the metals in their reduced, malleable, and ductile states, 

 phosphoric and bituminous materials of every denomination, 

 and generally those substances that burn with flame, belong 

 to this section. 



III. — Bodies abounding in oxygen. 



The substances remarkable for affording oxygen are the 

 phosoxvgen of the atmosphere, acids of every sort, espe- 

 cially those which readily undergo decomposition, water, 

 and all the metals in oxided and acid state. 



He said, by way of explanation, that the modern cele- 

 brated experiment for decompounding potash by means of 

 iron in a red-hot gun-barrel, was nothing more than a case 

 of double elective attraction. A phlogistuie of iron and an 

 oxide of potassium were brought within the sphere of each 

 other's action, in a convenient heat ; in which the oxvgen 

 quitted the potassium to unite with the iron, while the phlo- 

 giston, which had deserted the iron, associated itself with 

 the potassium, and thereby a phlogisture of potassium and 

 an oxide of iron were formed. He believed such action of 

 the metals upon each other was very common, and thought 

 the true theory of the operation of metallic plates in the 

 Galvanic pile would be ultimately explicable upon this 

 principle. 



Professor Mitchill explained, upon the principle of this 

 classification, the great and the small cheujical changes 

 which natural objects undergo, both in the workshops of the 

 artists and in the laboratory of Nature, llie constitution 

 of tiic numerous and extensive order of nieta's was de- 

 fined, in their state of oxide and acid, consisting of nie- 

 tal and oxygen, and in their ductile and resplendent forms, 

 composed of metal and phlogiston. And some metal', hq 



said, 

 s 



