452 Rev. W, Whewell on the Employment 



symbols is to be looked upon as consisting of mere abbrevia- 

 tions, which are not indispensably necessary : they need not 

 be used in chemistry, but they are generally convenient in 

 expressing the constitution of minerals, as they make the for- 

 mula shorter and more simple. In chemical investigations, it 

 would generally be better to use the other or systematic sym- 

 bols. In these it will be observed that none but small letters 

 are used (capitals and accents being confined to the abbreviated 

 symbols). All metallic elements are represented by two 

 letters : the single letters used are, 6, c, h, n, o, p 9 s. There 

 is, I think, no part of the system in which any ambiguity can 

 occur : thus S and si refer to silica and its base, s t s v , s' to 

 sulphur and its acids: C, ca, lime and its base; c, c\ c', carbon 

 and its acids : CM, Cu 9 cb, Cb, cr, cr, &c. various metals and 

 their combinations; N, na, soda and its base; n, w x , ri, nitro- 

 gen and its combinations. The use, however, of the grave 

 accent, as s\ rt, &c. for the sulphurous, nitrous, &c. acids, 

 would be almost superfluous, as these do not occur in 

 minerals. 



As an exemplification of the above symbols, take the con- 

 stitution of Alamandine and Melanite, according to Beudant 



Alamandine = (2 S -f 3 Fe) + 2 (S + A). 



=r (2s7+~o + 3/7+~o) + 2 (si + o + al + o) 

 = 4 si + 3fe + 2 al + 9 o. 

 Melanite = (2 S + 3 C) + 2 (S + Fe?). 



= (2 w + o + 3 ca + o) + 2 (si + o + fe + f o) 

 = 4 si -f- 3 ca + 2fe -f 10 o. 



The difference of these two expressions in the quantity of 

 oxygen disappears according to the views of Berzelius, who 

 considers S as si + 3 o 9 C as ca + 2 o, Fe as fe + 20, Fes 

 as/e + 3 o, A as al + 3 o. We have thus 



Alamandine = (2 si + 3 o + 3/e + 2o) + 2 (si + 3 o+a/+3o) 



Melahite = (2 si -f 3 o + 3 ca + 2 o)+(si + 3o + fe, +3o 



= 4 si + 3 ca + 2fe -f 24 o ; 

 and the two expressions are now analogous. 



The notation of Berzelius has already been widely diffused, 

 and much valuable information has been embodied in it* espe- 



