AVERAGE RESULTS OF ANALYSES OF SORGHUM, ETC. 209 



Twenty-five samples of sugar-cane juices, from the many varieties 

 of this plant grown in Louisiana, Cuba, Jamaica, Martinique, Guada- 

 lupe, and the East Indies, analyzed by several chemists, give the fol- 

 lowing average composition : Sucrose, 18.28 per cent ; other solids, 2.71 

 per cent. If, now, as in the case of the sorghums, we subtract the 

 sum of the solids (which was made up of ash, glucose, and other unde- 

 termined substances) from the sucrose, we have, as available sugar in 

 these juices, an average of 10.57 per cent — an amount even less than 

 that found present in the average juice of thirty-five kinds of sorghum 

 for long periods, as Avill be seen by reference to the charts and tables. 



Analysis of Juice at Different Stages. 



It has been supposed by some, that the increase in the amount of 

 sugar at certain periods is due to the drying up of the plant, and the 

 consequent concentration of the juice by evaporation. 



This view, although' apparently sui:)ported by some facts, is probably 

 erroneous, since (as will appear from the results of our determinations, 

 as shown upon either of the charts showing the average results for a 

 year) the amount of juice varies but little during the year ; but, owing 

 to continuous increase in the sucrose, glucose, and other solids, during 

 the season (as shown by the analyses, and indicated by the steady in- 

 crease in specific gravity), it follows, of necessity, that the amount of 

 water in the juice must as steadily decline. 



This, however, would hardly appear as the result of a drying up of 

 the plant; since, as has been show'n, neither the amount of jnice, nor 

 its composition, suffers any great change, even when a heavy rain-fall 

 siicceeds a period of 2:)rolonged drought. 



It appears rather a normal condition of the plant's growth ; and the 

 production of sugar seems to be accompanied by the elimination of a 

 certain amount of water. 



If, at any time, we might look for more concentration of juice by 

 the evaporation of water, and the consequent increase in the percentage 

 of the several constituents of the juice, it would seem to be during the 

 later periods of the plant's growth. If, now, we take the results for the 

 past season, as given in the general averages, we find that, for exam- 

 ple, the amount of total solids obtained in the juice were, in the 

 fifteenth, sixteenth, and seventeenth stages, 12.35, 12.56, and 12.30 

 per cent of the weight of the stripped stalks ; but the amount of water 

 in the juices at these periods was, for these respective stages, 51.19, 

 47.69, and 46.65 per cent of the weight of the stripped stalks. 



As will be seen, there is, in the above results, a slow diminution of 

 water, but no corresponding increase of the solids. 

 14 



