Oct. 1, 1919 Notes on the Composition of the Sorghum Plant 



17 



during the isolation of nitrogenous compounds described below, cal- 

 cium oxalate crystals were separated and identified in appreciable 

 quantities. Lack of opportunity has prevented the study of the history 

 of these acids during the development of the plant. Titration data on 

 juices are not included in this paper. They bear little significance, since 

 in all plant juices the acids occur as salts to a considerable degree and the 

 titration gives no idea of the absolute quantity of acids present. Suffice 

 it to say at this place that malic, tartaric, oxalic, citric, and aconitic acids 

 are present in sorghum juice. 



Fig. 14.— Development of the ash content in the various parts of the sorghum plant. 



These data prove conclusively the presence of pentosans in the gums 

 of sorghum juice. It is believed that the substances precipitated by 

 alcohol are true gums and not pectins, since the jell test described by 

 Goldthwaite (6) gave negative results. The ash, by qualitative tests, was 

 shown to consist mostly of calcium and magnesium with some potassium. 

 This is in accordance with the description of true gums by Haas and Hill 

 (7, p. 120). It is also in accordance with the findings of Anderson {3) 

 that sorghum juice, because of the gums present, absorbs over twice as 

 much calcium hydrate as is accounted for by titration. 



One-half liter of juice of specific gravity 1.078 was precipitated by 

 alcohol. The precipitate was dried and weighed. A portion of it was 

 used for ash and for nitrogen determinations. The rest was boiled in 

 122503°— 19 3 



