Section of Chemistry and Electricity. 393 



On the comparative value of Irish and Virginian Tobacco. By 



Edmund Davy, F.R.S., M.R.I. A. , $c, Professor of Chemistry 



to the Royal Dublin Society. 



In the year 1829-30 the cultivation of tobacco in Ireland excited 

 much attention among agriculturists, and several hundred acres of 

 it were raised in different counties ; in consequence, the attention of 

 the Royal Dublin Society was directed to the subject, and the author 

 was requested by a select committee of that body to institute ex- 

 periments on tobacco with a view to determine some questions of a 

 practical nature, as whether its root contained nicotin, and in what 

 quantity, and to ascertain the comparative value of Irish and Vir- 

 ginian tobacco. 



The author's experiments were made on average samples of Vir- 

 ginian and Irish tobacco ; for the former he was indebted to the 

 kindness of Mr. Simon Foot, and for the latter to Messrs. Wild, 

 Cuthbert, Callwell, and Brodigan. From a number of experiments 

 the author was led to conclude that the dried roots of Irish tobacco 

 contain from four to five parts of nicotin in one hundred parts ; and 

 that one pound of good Virginian tobacco is equivalent in value to 

 about 24- pounds of good Irish tobacco. 



After the author had finished his experiments it was gratifying 

 to him to be informed that some manufacturers estimate one pound 

 of Virginian tobacco as equivalent in value to about two pounds 

 of Irish. Hence there seems to be a pretty near coincidence be- 

 tween their results and those derived from a chemical examination. 



On Nicotin and some of its Combinations. By Edmund Davy, 



F.R.S., M.R.I. A.) &h; Professor of Chemistry to the Royal 



Dublin Society. 



When the author commenced his experiments in 1829 on Irish 

 and Virginian tobacco, nearly all our knowledge of the peculiar 

 principle in tobacco, called Nicotin by the late M. Vauquelin, was 

 confined to his paper on tobacco*. By a series of processes in which 

 the expressed juice of tobacco was reduced to one fourth of its 

 bulk by evaporation, then digested in alcohol, distilled, again con- 

 centrated, dissolved in alcohol, then evaporated to dryness, dissolved 

 in water, saturated with potash, and distilled to dryness, Vauquelin 

 seems to have obtained a fluid nearly approximating to the nicotin 

 recently procured. 



In obtaining nicotin, the author avoided the circuitous processes 

 of Vauquelin, and adopted only the simple method of exposing to- 

 bacco to the action of a solution of potash and subsequent distilla- 

 tion. The alkali employed was in some cases weak and in others 

 strong. In some instances it was macerated on the tobacco for one 

 or two days ; in others, it was added to the tobacco in the retort 

 and distilled at once. Other fixed alkaline substances in solution, 

 as soda, barytes, strontites, lime, may be substituted for potash. 

 Distillation was occasionally carried on below, but in general at the 



• Annates de Chimie, tome lxxi. 

 Third Series. Vol. 7. No. 41. Nov. 1835. 3 E 



