Wells & Foote — One Hundred Years of Chemistry. 269 



number of atoms in a formula, as in N 2 5 . This was a 

 marked improvement over the hieroglyphic symbols pro- 

 posed by Dalton, which were set down as many times as 

 the atoms were supposed to occur in formulas, forming 

 groups of curious appearance, but in some respects not 

 unlike some of our modern developed formulas. The 

 advantages of Berzelius 's symbols were their simplicity, 

 legibility, and the fact that they could be printed without 

 the need of special type. It is true that at a later period 

 Berzelius used certain symbols with horizontal lines 

 crossing them to represent double atoms, and that these 

 made some difficulty in printing. It should be mentioned 

 also that Berzelius at one time made an effort to simplify 

 formulas by placing dots over other symbols to represent 

 oxygen, and commas to represent sulphur atoms. Exam- 

 ples of these are : 



• ••• >i 



CaS, calcium sulphate ; Fe, iron disulphide 



This form of notation was quite extensively employed 

 for a time, especially by mineralogists, but it was entirely 

 abandoned later. 



It is interesting to notice that Dalton, who lived until 

 1844, to reach the age of 78, differed from other chemists 

 in refusing to accept the letter- symbols of Berzelius. 

 In a letter written to Graham in 1837 he said: " Ber- 

 zelius 's symbols are horrifying. A young student in 

 chemistry might as soon learn Hebrew as to make him- 

 self acquainted with them. They appear like a chaos of 

 atoms . . . and to equally perplex the adepts of science, 

 to discourage the learner, as well as to cloud the beauty 

 and simplicity of the atomic theory. ' ' 



This forcibly expressed opinion was apparently tinged 

 with self-esteem, but there is no doubt that Dalton was 

 sincere in believing that the atoms were best represented 

 by his circular symbols, because, as is well known, he 

 thought that all the atoms were spherical in form, and it 

 is evident that circles give the proper picture of spherical 

 objects. At the present time some insight as to the 

 structure of atoms is being gained, and it appears possi- 

 ble that the time may come when pictures of their 

 external appearance that are not wholly imaginary may 

 be made. 



