CHEMICAL ANALYSES OF TOBACCO. 



277 



exist iu tlic plant, and as we are still iii uncertainty as to the chemical character (whether acid or indifl'ereut) of 

 tin: hitherto unstudied constituents of the leaf, it is not possible to say, with any certainty, from the results of 

 the analysis, or even from the examination of the extracts or decoctions of the plant, precisely in what state of 

 combination the constituents may have existed in the interior of the vegetable cell. Nevertheless, it is of some 

 interest to compare the respective equivalence of the acids and bases found in the analysis with a view of 

 ascertaining if this proportion bears any relation to the combustibility of the leaf. The equivalence is obtained 

 by dividing the percentage of each ingredient by its molecular weight and multiplying tbequotient by theatomicity. 

 If we then deduct from the sum of the equivalents of the inorganic bases the sum of the equivalents of the 

 inorganic acids of the ash, \ve have as the residue the equivalence of the inorganic bases (potash, soda, lime, etc.), 

 that are to be compared with the organic acids and nitric acid of the plant. The equivalent ratio therefore expresses 

 the relative equivalence of the organic acids and nitric acid (taken as unity) with that of the inorganic bases with 

 which these acids may be supposed to be combined. Applying this process to samples Nos. 30 and 35, we have : 



Son. of samples. Equivalent ratios. 



30 Orgauic and nitric acids : Bases=l : 1.345 



35 Organic and nitric acids : Baseg=l : 0.970 



From the foregoing it will be seen that the sample No. 30 contains'^ large excess of bases over the amount 

 requisite to form neutral salts with the acids named above, or, in other words, the quantity of mineral bases iu the 

 sample No. 30, after deducting the amount required to form neutral salts with the inorganic acids of the ash, is 

 about one-third greater than is required to form neutral salts with the organic acids and nitric acid of the leaf; 

 whereas in the sample No. 35 the proportion of bases is less than is required to form neutral salts. 



In this and the following calculations, both ammonia and nicotine are omitted, as on account of the volatility 

 and readily decomposable character of the organic salte of these bases, and their relatively small amount, they 

 cannot be supposed to materially affect the combustibility of the tobacco. Nitric acid has been included with the 

 organic acids, for the reason that it is readily decomposed iu contact with organic matter, and at a low heat, and, 

 like the organic aeids, leaves the base with which it was combined iu the state of carbonate. 



On the following table are given the equivalent ratios, proportions of potassium carlx':iate,and, for comparison, 

 also the proportions of nitric acid, together with the results of the burning tests, for sample No. 37 and the different 

 seed-leaf varieties : 



RELATIONS BETWEEN EQUIVALENT RATIOS AND BURNING QUALITIES. 



The results communicated on the foregoing table show unmistakably the existence of a relation between the 

 combustibility and the relative proportions of acids and bases present in the leaf. In general, those samples bum 

 best wherein the excess of bases is most marked, and it will be seen that the relative combustibility is independent 

 of the proportion of potassium carbonate the leaf yields on incineration, and, to a large extent, of the proportion 

 of the nitric acid; nevertheless, the effects of the latter are quite apparent in the sample No. 16. In Nos. 25 and 

 30, while the equivalent ratios are nearly equal, the degree of combustibility although both burn well is quite 

 different, possibly owing to the much larger percentage of albuminoids in No. 25. Sample. No. 22 was composed 

 of leaves of very diverse appearance, mostly dark in color, but sometimes light. One leaf, however, was very 

 light and thin, and this .specimen, as stated, burned to the end of the strip. The reactions of the aqueous extracts 

 of these samples to test papers wero as follows: No. 35, acid; Nos. 1C, 22, and 37, neutral; Nos. 25, 30, and 34, 

 alkaline. No. 34 was strongly alkaline. 



The foregoing results would appear to indicate that the rational conduct of the operation of curing smoking 

 tobaccos, and especially the seed-leaf varieties, would involve the destruction of a larger proportion of the organic 

 aculs (citric and malic acids) by fermentation, the operation being in some instances carried to the extent of 

 transforming the salts of these acids, in part, into carbonates. It is hardly necessary to say that this operation 

 would result iu setting free a large proportion of the nicotine, which would volatilize during the process. 



