892 



APPENDIX. 



hence exists in large quantities in Liebig's "extract of meat." It is often found 

 also in pathological" fluids. This is the only acid of the series which possesses any 

 power of rotating the plane of polarized light ; it is otherwise indistinguishable 

 from the preceding ethylidene-lactic acid, and is generally represented by the same 

 formula. The free acid has dextro-, the anhydride Isevo-rotatory action. The 

 specific rotation for the zinc salt in solution is 7. 65 for yellow light. 



[FIG. 231. 



[FiG. 232. 



Zinc Sarcolactate. (After Kiihne.)] 



Calcium Sarcolactate. (After Kiihne.)] 



The zinc and calcium salts [Figs. 231 , 232] for sarcolactic acid are more soluble, 

 both in water and alcohol, than those of ethylidene-lactic acid, but less so than 

 those of ethylene lactic acid, and the same salts of ethylene-lactic acid contain 

 more water of crystallization than those of the other two. 



Heintz 1 has compared the above acids to the modifications capable of existing in tartaric 

 acid. 2 



Hydracrylic acid, the fourth in this series of lactic acids, is distinguished by the nature of its 

 decomposition on heating. It is never found as a constituent of animal bodies. 



OXALIC ACID SERIES. 



Oxalic Acid. H 2 C 2 4 . 



In ^he free state this acid does not occur in the human body. Calcic oxalate, 

 however, is a not unfrequent constituent of urine, and enters into the composition 



[FIG. 233. 



Calcium Oxalate.] 



of many urinary calculi, the so-called mulberry calculus consisting almost entirely 

 of it. It may occur in feces, and in the gall-bladder, though this is rarely observed. 



1 Op. cit. 



- See, further, Wislicenus, op. cit. Also Ann. d. Chem. u. Pharm., Bd. clxvi., S. 3; Bd. clxvii., 

 S. 302, and Zeitschr. f. Chem., Bd. xiii., S. 159. 



