TOBACCO 235 



open in these branches of the industry, but as yet we are not in a 

 position to say more than that the whole process is controlled by 

 bacteria. 



§6. TOBACCO. 



This industry begins to have greater interest for us at the present 

 day, because of its growing importance in Ireland, and because of the 

 growing recognition of the fact that the plant can be easily cultivated 

 in this country. In view of the recent withdrawal of restrictions on 

 its growth in Scotland, we may confidently look forward to a still wider 

 expansion of the tobacco industry. 



Tobacco is obtained from plants which are natives of tropical America 

 and Eastern Asia. It is a herbaceous plant, three to six feet high, with 

 large, somewhat hairy leaves. There are two main phases in the 

 preparation of this leaf. 



1. The curing process ; 



2. The sweating or fermentation process. 



1. Curing. The leaves are hung up in barns, suspended in rows 

 from long laths, in order to undergo a partial drying. They conse- 

 quently wilt and take on a somewhat brown colour. It may take four 

 weeks or more before the right condition has been reached. During 

 this time the moisture, temperature, and ventilation are judiciously 

 regulated, for the acquirement of a good flavour depends on the proper 

 regulation of these conditions as well as immunity from the attacks of 

 moulds and other pests. 



The development of the flavour has been carefully studied but not 

 explained. At first there is a decided flavour of cucumbers ; this is 

 replaced later on by the straw smell of cured tobacco. The further 

 development is completed during the second stage. The curing effects 

 a change of colour, the leaves assuming the familar brown colour of 

 wilted leaves. The chemical composition is naturally altered by the 

 curing, the most important changes are : (1) a change of the starch 

 into sugar ; (2) a partial disappearance of the sugar ; (3) a decomposi- 

 tion of proteid matter, with formation of amido-compounds ; (4) a 

 decrease of fatty matter and of tannin. In fact these changes are the 

 same as those which most leaves undergo during the process of wilting, 

 but what is still unexplained is the development of the substances in 

 the tobacco-leaves which cause them to be different from all other 

 leaves. 



