LECTURE III.] HISTORY OF CHEMISTRY. 33 



whose behaviour seems to indicate that they are not decom- 

 posable. Examples of these are : i, Heat (Calorigue) \ 2, 

 Light ; 3, Oxygen ; 4, Hydrogen ; 5, Nitrogen (Azote}. The 

 second class contains the acidifiable bases, such as sulphur, 

 phosphorus, carbon, &c. The third embraces the metals ; the 

 fourth the earths ; and the fifth the alkalies, which, as is well 

 known, had not at that time been decomposed. The names 

 of the substances belonging to the second, third, and fourth 

 classes are for the most part unchanged ; the alkalies are 

 called potash, soda, and ammonia. 1 For all these substances, 

 which, with the exception of ammonia, were regarded as ele- 

 ments, the authors observed the principle of designating each 

 by a single word. 



The radicals constitute an appendix to the elements. These 

 are substances which they regard as decomposable, but which 

 exhibit certain resemblances to elementary bodies. 



Next come the binary substances, consisting, as they do, of 

 two elements. The acids occur in this class. According to 

 the theory of Lavoisier, the acids all contain oxygen. Their 

 names are in each case composed of two words, of 'which the 

 first is common to them all and indicates their acid character 

 (acide\ while the second is a specific name indicating the 

 element or radical occurring in each. Thus we have acides 

 sulfurique, carboniquc, phosphorique, nitrique, etc. Two acids 

 containing the same element or radical are distinguished by the 

 different termination of the specific name ; that containing the 

 smaller proportion of oxygen receiving the termination eux, 

 whereby such names as acides sulfureux, nitreux, etc., are 

 obtained. 2 Hydrochloric acid is called acide muriatique^ and 

 the existence of oxygen in it is assumed ; while oxygen is sup- 

 posed to be present in still greater quantity in chlorine the 

 acide muriatique oxigene? 



The names of the binary substances of the second group, 

 i.e., of the basic compounds containing oxygen, are formed in 

 a manner exactly similar. For these the general designation 



1 Nomenclature Chimique. 67. a Ibid. 85-86. 3 Ibid. 87. 

 C 



