24 BURNING QUALITIES OP TOBACCO. 



SUMMARY. 



The principal facts brought out by the experiments which have 

 been described on the relation of the chemical composition to the 

 burning qualities of tobacco may be briefly summarized in the follow- 

 ing general statements : 



' (1) The fire-holding capacity is dependent primarily on the con- 

 tent of potash combined with organic acids. 



(2) Lime in general does not greatly affect the fire-holding capac- 

 ity, but is an essential factor in the production of a good ash. 



(3) Large amounts of magnesia tend to injure the capacity for 

 holding fire. 



(4) Chlorin injures the burning qualities, but it seldom happens 

 that tobacco contains enough of this element to do any serious harm. 



(5) Sulphates in general injure the burning qualities, but the 

 effects are not so marked when all the sulphuric acid is combined 

 with potash. 



(6) So far as is known none of the organic constituents of tobacco, 

 with the possible exception of the so-called tarry acids and the albu- 

 minoids, exert a very important influence on the burning qualities. 



From these conclusions it appears that the principal objects to 

 be attained in efforts to improve the burning qualities of tobacco by 

 breeding and by improved methods of production, especially in the 

 use of the proper fertilizers, are (1) a relatively high content of pot- 

 ash combined with citric and malic acids, with a minimum amount 

 of inorganic salts, especially chlorids and sulphates; (2) a moderate 

 content of lime; (3) a comparatively small percentage of magnesia, 

 and (4) a low content of organic nitrogenous compounds, more espe- 

 cially the albuminoids or proteids. Of these problems the first 

 mentioned is altogether the most important from a practical stand- 

 point and also the most difficult to solve. It has long been known 

 that the muriate can not be used as a source of potash in the pro- 

 duction of tobacco which is intended for smoking purposes, because 

 of the injurious effects of the chlorin. The other available sources 

 of potash at the present time are the sulphate, the carbonate, and the 

 silicate. 



Schlosing," in his experiments with the use of the sulphate as a 

 fertilizer for tobacco, found that the potash is assimilated, while the 

 content of sulphuric acid is not increased. Jenkins,^ on the other 

 hand, in experiments conducted at the Connecticut Agricultural 

 Experiment Station and extending over a period of several years, 

 has shown that the composition of tobacco ash is profoundly modi- 

 fied by the use of different forms of potash and that applications of 



o Landw. A' ers. Stat., 3, 98. » Ann. Rpt. Conn. Agr. Expt. Sta., 1896. 



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