20 



INFRA-RED REFLECTION SPECTRA. 



In conclusion, it may be said that, from all of the silicates examined, 

 there is no regularity in the position of the maxima such as obtains in the 

 sulphates and the carbonates. It is true that in a few cases the maxima 

 are in common, but, on the whole, the evidence indicates that there is no 

 uniform group of atoms acting in common as is found in the sulphates 

 and carbonates. In other words, the silicon radical is different in the 



so; 



40 



c 

 o 



01 



QJ 



.30 



CC20 



10 



5 6 7 8 9 10 II 



Fig. 13. Spodumene (a); Sodium silicate. 



IZfl 



different minerals. This seems to be the necessary interpretation to be 

 given, for it has been impossible to work out a relation with the molecular 

 weight of the molecule, such as exists in the carbonates and sulphates, to 

 be discussed on a later page. 



