30 



CHEMICAL COMPOSITION OF THE TOBACCO PLANT. 



The chemical composition of the tobacco plant has been studied by 

 the stations from various points of view, The different parts of the 

 plant have been analyzed to determine the amount of plant food con- 

 tained in them. Studies have been made to ascertain the effect of 

 curing and fermenting- upon the composition of the leaf and stalk; and 

 the composition of the refuse, such as tobacco dust and tobacco stems, 

 has been determined to show its value as a fertilizing material. A 

 number of analyses of tobacco ash are also reported. The most impor- 

 tant results are here briefly summarized. 



At the Colorado Station, 1 the analyses of the ash of a number of 

 varieties of tobacco showed that the composition of the samples grown 

 was similar to the average composition of tobaccos produced in Con- 

 necticut and elsewhere. One qualitative test for acids in the leaf was 

 made, and acetic, pectic, citric, malic, and oxalic acids were found. 

 The leaves also contained considerable quantities of resinous and fatt}^ 

 substances. The ash of Havana tobacco grown on poor soil was found 

 to contain more than twice as much silica but considerably less lime, 

 potash, and carbon dioxid than the same variety grown on rich soil. 



A study of the occurrence of nitrates in tobacco at different stages 

 of growth made at the North Carolina Station 2 pointed out that the 

 nitrates are confined almost entirely to the stalk and stems in the young 

 plants. During the later growth of the plant practically no nitrates 

 were found. Samples of tobacco stems from different sources were 

 analyzed by the station and compared. Stems of cigar tobacco from 

 Missouri, Connecticut, and Ohio and stems of export tobacco from 

 Virginia contained 0.83, 0.72, 0.60, and 0.54 per cent of nitrates, 

 respectively, while stems of cigarette tobacco from North Carolina con- 

 tained 0.15 per cent. No nitrates were found in North Carolina stems 

 of chewing tobacco or in the dust from the North Carolina product. 

 In general the total nitrogen content was smaller in North Carolina 

 tobacco stems than in those obtained from tobacco grown in the 

 other States mentioned. Whole leaf of North Carolina bright tobacco 

 cured by the leaf -curing process contained 16.23 per cent of potash, 

 while the same kind of tobacco cured b}^ the stalk-curing process con- 

 tained 21.81 per cent. Other variations in the composition of tobacco 

 resulted from the two methods of curing, but it is believed all these 

 differences in the chemical composition are due mainly to the manner 

 and time of harvesting, and that in general the composition of tobacco 

 cured by similar methods is not materially affected by separating the 

 leaf from the stem before curing if the condition of the tobacco is- 

 the same when put into the barn. 



1 Colorado Station Bui. No. 10. 2 North Carolina Station Bui. No. 90a- 



