100 Scientific Proceedings, Royal Dublin Society. 



adopt the more recent formula of M. Berthelot 1 for the hydrate of 

 humic acid Ci 8 H 16 7 , giving a molecular weight of 344 for a mono- 

 basic acid, it will make very little difference in the quantities of 

 humic acid as calculated above. 



I find that dopplerite decolourises a solution of phenol-phthalein 

 made pink by the addition of a minute quantity of alkali; the 

 reaction may possibly be utilized in titrating the acidity of this 

 and other humus substances. 



1 Chimie Vegetale et Agricole, IV., p. 125. 



