308 HISTORY OF CHEMISTRY. 



metal named Cerium, was discovered in 1803, by Hisingd- and Berze 

 lius, in a rare Swedish, mineral known by the name of Cerit. Mosan- 

 der more recently has found combined with Cerium, other new metals, 

 which he has called Lanthanium, Didymium, Erbium, and Terbium : 

 M. Klaus has found a new metal, Ruthenium, in the ore of Platinum ; 

 and Rose has discovered in Tantalite two other new metals, which he 

 has announced under the names of Pelopium and Niobium. Svan- 

 berg is said to have discovered a new earth in Eudialyt, which is sup- 

 posed to have, like the rest, a new radical. If these last discoveries 

 be confirmed, the number of simple substances will be raised to sixty- 

 two^ 



2. Attempts have been made to indicate the classification of chemi- 

 cal substances by some peculiarity in the Name ; and the Metals, for 

 example, have been designated generally by names in um, like the 

 Latin names of the ancient metals, aunim, ferrum. This artifice is a 

 convenient nomenclature for the purpose of marking a recognized dif- 

 ference ; and it would be worth the while of chemists to agree to make 

 it universal, by writing molybdenum and platinum ; which is some- 

 times done, but not always. 



3. I am not now to attempt to determine how far this class, 

 Metals, extends ; but where the analogies of the class cease to hold, 

 there the nomenclature must also change. Thus, some chemists, as 

 Dr. Thomson, have conceived that the base of Silica is more analo- 

 gous to Carbon and Boron, which form acids with oxygen, than it is to 

 the metals : and he has accordingly associated this base with these 

 substances, and has given it the same termination, Silicon. But on 

 the validity of this analogy chemists appear not to be generally 

 agreed. 



4. There is another class of bodies which have attracted much 

 notice among modern chemists, and which have also been assimilated 

 to each other in the form of their names; the English writers call i ni 

 them Chlorine, Fluorine, Iodine, Bromine, while the French use the 

 terms Chlore, Phtore, lode, Brome. We have already noticed the 

 establishment of the doctrine that muriatic acid is formed of a base, 

 chlorine, and of hydrogen, as a great reform in the oxygen theory ; 

 with regard to which rival claims were advanced by Davy> and by 

 MM. Gay-Lussac and Thenard in 1809. Iodine, a remarkable body 

 which, from a dark powder, is converted into a violet-colored gas by 

 the application of heat, was also, in 1813, the subject of a similar 

 rivalry between the same English and French chemists. Bromine 



