14 BUKNING QUALITIES OF TOBACCO. 



made up to 200 c. c. and aliquot portions were taken for analyses. 

 The principal constituents of the extract are the chlorid, sulphate, 

 nitrate, citrate, and malate of potassium, together with ammonium 

 and nicotine salts and small quantities of lime and magnesia. For 

 comparison, the ash of the extracted tobacco was also examined and 

 it was found that practically all of the phosi^horic acid, about one- 

 half of the magnesia, all of the oxalic acid, and tlie greater portion 

 of the lime remain in the leaf, while the extract contains nearly all 

 the chlorin, all the potash, malic, citric, and nitric acids, and most 

 of the sulphuric acid. About one-half of the total ash is extracted 

 from the leaf by this process, and this seems to contain all the con- 

 stituents which impart to the tobacco the capacity for holding fire. 



An extract of a tobacco having poor burning qualities was pre- 

 pared in the same way, and it also showed the powder to impart the 

 capacit}^ for holding fire, but as nearly as could be measured this 

 power was only about one-fifth of that shown by the extract from 

 the tobacco having good burning qualities. It differed from the 

 latter as regards composition in that it contained about five times as 

 much sulphuric acid, twice as much magnesia, and considerably less 

 nitric acid. The total quantity of jDotash was about the same in the 

 two extracts, so that the extract from the tobacco with poor burning 

 qualities contained much less potash in combination w ith the organic 

 acids. The difference in composition of these extracts, then, obtained 

 from tobaccos having good and bad burning qualities, indicates that 

 the principal factor favoring the burn is the potash in excess of the 

 amount required for combining with the mineral acids. 



EFFECTS OF THE VARIOUS CONSTITUENTS OF THE ASH ON THE 

 BURNING QUALITIES OF TOBACCO. 



The experiments previously described show conclusively that those 

 compounds which are most important in promoting the burn of 

 tobacco can be removed by extraction with water; but the water 

 extract is a complex mixture of salts, and it is therefore desirable 

 to determine the relative effects of each of these constituents. In 

 order to do this, solutions of certain definite strength were prepared 

 of all of the salts which are found in the extract, and the effects of 

 all these on the burning qualities of various samples of tobacco when 

 applied singly or in combination were noted. In testing the effects 

 of any one base combined with the different acids the solutions were 

 all made of such strength that the quantity of the basic element was 

 always the same, regardless of the molecular weights of the salts used 

 in the experiments. The salt solutions were applied to small strips 

 of the leaf, either by placing them in a watch glass and pouring over 

 them a quantity of the solution to be tested just sufficient to thor- 



105 



