MISCELLANEOUS COMPOUNDS. 



61 



TARTARIC ACID (C*H 6 Oo). 

 (Cleavage parallel to a. Curve a, fig. 47.) 



In fig. 47 curve c is for a film melted and crystallized between thin 

 cover-glass, = 0.09 mm., while curve a is for a cleavage section, 

 / = 0.32 mm. Curve b is for a film melted between plates of rock salt. 

 This compound has the properties of a divalent alcohol and of dibasic 

 acids. The curves are characteristic of alcohols, having an absorption 

 band from 2.9 to 4 /*, followed by a transparent region at 4.6 /x,, which is 

 characteristic of carbohydrates. 



to 



01?. 4 6 8 



FIG. 48. Phloroglucin (a) ; Malic acid. 



PHLOROGLUCIN (C 8 H 8 (OH) 8 +2H 2 O). 



(f = O.O2. Fig. 48.) 



This belongs to the group containing water of crystallization. 

 Apparently it is an exception to the rule. The sample turned light 

 brown on melting, and it is quite probable that the H 2 O was partly 

 expelled. The compound belongs to the phenols, hence one would 

 expect a band at 3 to 3.2 /*, the latter being the characteristic of benzine. 

 There are small water bands at i .45 and 2.05 /u,. 



