304 



APPENDIX. 



compound of nitrogen, hydrogen, and oxygen. 2d. Those 

 metals which by combining with oxygen form the alkaline 

 earths; viz. calcium, magnesium, barium, and strontium. 

 Calcium is the base of lime, magnesium of magnesia, and so 

 on. These metallic substances are of the colour of silver. 

 3d. Those metals which by combining with oxygen consti- 

 tute the remainder of the earths. These are silicum, alu- 

 mium, zirconium, glucinum, yttrium, and thorinum. These 

 are presumed metals, for the earths, of which they are sup- 

 posed to constitute the bases, have been as yet but partially 

 decomposed : respecting some of them little is known. 4th. 

 The metals which absorb oxygen and decompose water at a 

 high temperature. These are iron, tin, zinc, cadmium, and 

 manganese. 5th. Those metals which absorb oxygen at 

 different temperatures, but do not decompose water at any 

 temperature. This class is composed of twelve distinct 

 metals, viz. osmium, cerium, tellurium, titanium, uranium, 

 nickel, cobalt, copper, lead, antimony, bismuth, and mercury. 

 6th. Those metals which do not decompose water, but ab- 

 sorb oxygen, and are thereby converted into acids. These 

 are arsenic, molybdenum, tungsten, chromium, columbium, and 

 selenium. 7th. The metals which do not decompose water, 

 nor absorb oxygen from the atmosphere at any tempera- 

 ture. These are platina, gold, silver, palladium, rhodium, 

 and iridium. 



LESSON m. 



A Retort, Jig. 48, Engr. VI. A vessel in the shape of a 

 pear, with its neck bent downwards, used in distillation. The 

 extremity of the neck may be fitted into another glass ves- 

 sel, called a. receiver. Fig. 48, represents a common glass 

 retort, an instrument much used in chemical laboratories for 

 various purposes. A tubulated retort is an instrument like 

 the latter, with a tube at the bend T, and with a ground glass 

 stopper to fit it. This is the most useful kind of retort, as 

 materials may be put in through the tube during the opera 

 tion. The student may find engravings and descriptions of 

 a chemical apparatus in Parkes' Rudiments of Chemistry. 



Note. Chlorine may be procured by heating in a glass 

 retort a mixture of equal weights of the black oxyd of man- 

 ganese and common muriatic acid (spirit of salt.) The gas 



