52 INFRA-RED TRANSMISSION SPECTRA. 



In the present examination curve a is for a section transmitting a 

 brown color, while curve b was light green. Both show the hydroxyl 

 band at 3 /*,, while additional bands occur at 4.3, 4.7, 5.0, 5.3, 5.6, 5.9, 

 6.6, and 7.4 /u,, many of which are in common with those of quartz. 



SODIUM METAPHOSPHATE (NaPo 3 ). 

 (Fused transparent glass; t = 0.37. Fig. 38.) 



This substance was examined in connection with the following phos- 

 phates to learn the behavior of phosphorus in a compound. There is a 

 wide absorption band at 4 and a second at 6 p.. 



10 



I Z 6 d S to 14- U. 



FIG. 38. Sodium metaphosphate (a) ; Meta phosphoric acid (b) ; Ortho phosphoric acid (c). 



META PHOSPHORIC ACID (HPO 3 ). 

 = 0.25 mm. Curve b, fig. 38.) 



This substance comes in transparent cylindrical sticks like KOH. It 

 was melted between a plate of rock salt and one of glass. The latter 

 became loose on cooling, and was removed. The compound is too 

 opaque for examination beyond 3 /A. 



ORTHO PHOSPHORIC ACID 

 (t = 0.12 mm. Curve c, fig. 38.) 



This compound is formed from HPO,, and also from P 2 O 5 , standing 

 in moist air. 



