Tobacco Leaves Part 4

Potash About 27% Soda About 3% Lime About 40% Magnesia About 9% Sodium Chloride About 9% Sulphuric Acid About 3% Silica About 5% Lime Phosphate About 4%

REMARKS ON SOME OF THE SUBSTANCES FOUND IN TOBACCO

_Nicotine_

Of all the substances found in tobacco, nicotine is the most important.

Nicotine in the pure state is a colorless liquid having a specific gravity of 1.027. It is an organic base having the chemical formula C{10}H{14}N{2}. It is extremely acid and burning to the taste, and is a virulent poison. It easily volatilizes; is inflammable, and is soluble in water, alcohol, ether and some fixed oils. Nicotine has the characteristic peculiar odor of tobacco.

The amount of nicotine in tobacco is said to depend on the nature of the soil in which it is grown; rich, heavy soils and strong nitrogenous manuring favor the production of a large nicotine content; and light, sandy soils the opposite.

Moreover the nicotine content depends on the age and development of the plant.

An investigation by Chuard and Mellet showed nicotine contents of leaves:

In young plants 7 weeks old contained .0324% In plants 10 weeks old contained .0447% In plants 13 weeks old contained .4989% In plants 19 weeks old contained .9202%

The longer the plant is permitted to grow the larger will be its nicotine content.

Schlossing has made a similar investigation and found that in the same plant the nicotine content varies from 0.79% when young to 4.32% when fully matured. Most nicotine is found in the ribs and veins.

H. B. c.o.x (_American Druggist_ V. 24, 1894, p. 95) investigated the nicotine contents of various manufactured tobaccos. These were not "proprietary tobaccos" but samples obtained from different sources at random. His results are given here:

NICOTINE CONTENTS OF DIFFERENT TOBACCOS

_Nicotine_

Syrian Tobacco leaf (a) .612% American Chewing Leaf .935% Syrian Tobacco Leaf (b) 1.093% Chinese Tobacco Leaf 1.902% Turkish Coa.r.s.e Cut 2.500% Golden Virginia (whole strips) 2.501% Gold Flake Virginia 2.501% Navy Cut (light) 2.530% Light Kentuckian 2.733% Navy Cut (dark) 3.64 % Best "Bird's Eye" 3.931% Cut Cavendish (a) 4.212% Best s.h.a.g (a) 4.907% Cut Cavandish (b) 4.970% Best s.h.a.g (b) 5.00 % Algerian Tobacco (a) 8.813% French Grown Tobacco 8.711% Algerian Tobacco (b) 8.90 %

The average of a number of samples of Syrian tobacco showed 1 to 2% nicotine, Manila and Havana 1 to 3%, Virginia and Kentucky from 2 to 7%, and French tobaccos about 9%.

Most of the nicotine in tobacco becomes volatilized and decomposed during combustion; a small part, however, may form a solution with the water which is also one of the combustion products. One of the decomposition products of nicotine is

_Pyridine_

Pyridine is usually found in tobacco smoke. When condensed it is a colorless non-oily liquid and is considerably less toxic than nicotine.

Reference will be made later on to the effects of nicotine and pyridine on the human system.

_Potash_

Potash is important as on its amount depends the burning qualities of the tobacco. It is sometimes present in the ash to the extent of 30%, being converted into pota.s.sium carbonate by burning. Not only for free burning is the potash valuable, but also for the better volatilization of the nicotine and other substances. The more perfect the combustion, the fewer deleterious compounds are formed.

Chlorides, if present, r.e.t.a.r.d the burning of the tobacco, and hence a tobacco which contains a high percentage of chloride, even if it is rich in potash salts, is a poor burning tobacco and therefore faulty. While it is important that the burning should be free and the volatilization as perfect as possible, yet the smoker does not want his tobacco to burn too rapidly. To meet this some manufacturers prepare "slow burning" tobaccos generally by the addition of some chemical which checks the potash.

The aroma and flavor of the tobacco depend to a great extent on the waxes, resins and oils, as well as on certain of the organic acids.

REFERENCES

U. S. DISPENSATORY. 1907 (19th Edition).

KISSLING. _The Chemistry of Tobacco._ _Scientific American_ (Supp.) 1905, Vol. 60, No. 1560.

CHUARD & MELLETT. _Variation de Nicotine dans les differents organes de la plante de Tabac._ Comp. Rend. Acad. d. Sc. (Paris) 1912. Vol. 155, p. 293.

PEZZOLATO, A. _Conferenza Sulla Chimica applicato alla technologia del Tabacco._ (Rome. 1903.)

WOLF, JACOB. _Der Tabak und die Tabak fabrikate._ Chapter III. Leipzig, 1912.

SCHLOSSING. _Sur la production de la nicotine par la culture du Tabac._ Compt. Rend. Acad. d. Sc. (Paris), 1910. Vol. 151, p. 23.

CHAPTER VI

THE CURING OF TOBACCO LEAF

OBJECTS OF CURING. METHODS.

THE CURING OF TOBACCO LEAF

The "curing" of tobacco leaf is the process of drying out which has for its object the following specific actions:

(1) The expelling of the sap and superfluous moisture.

(2) The completion of the "yellowing" process and the fixing of the desired color.

(3) The preservation of the juices, etc., which give the characteristic flavor and aroma.

(4) To give the necessary toughness and suppleness to the leaf.

The first part of the curing is done by the grower in curing sheds on the farm immediately after the cutting of the crop; the final part, or the fermentation part is usually done by the leaf dealer or manufacturer in special buildings called leaf-houses.

There are three methods of curing in use by the growers, i. e., sun curing, air curing, and artificial heat curing. In the case of the tobacco known as _Perique_ the curing process is more or less peculiar to itself.

"Sun" and "air" curing are much slower processes than the curing by artificial heat.

All cigar leaf tobacco is sun-cured, and as a general rule pipe smoking and chewing tobacco are cured by artificial heat.

For the purpose of drying and curing by artificial heat, the leaf is hung up in specially constructed curing houses or sheds. It is found that after the exposure to the sun for the first process of "yellowing" tobacco leaf still contains 1 lb. of water approximately in each plant. The first part of the process of curing consists in drawing off this superfluous moisture. Dry heat is applied at a temperature of 90 F. to 120 F. for about 16 to 30 hours to effect this. A further exposure of about 48 hours at a temperature of 125 or so is necessary to complete the curing, and fix the color.

The stems and stalks being thicker take a longer time and generally require 9 to 10 hours further exposure and a temperature which may range as high as 175 F. before they are fully cured, the temperature being graded hourly until the maximum necessary is reached.