L 122 3 



charcoal and quicklime ; they then afford pure alco- 

 hol by distillation. The cognac brandies, I find, con- 

 tain vegetable prussic acid, and their flavour may be 

 imitated by adding to a solution of alcohol in water of 

 the same strength, a few drops of the ethereal oil of 

 wine produced during the formation of ether,* and a 

 similar quantity of vegetable prussic acid procured 

 from laurel leaves or any bitter kernels. 



I have mentioned ether in the course of this Lec- 

 ture ; this substance is procured from alcohol by distil- 

 ling a mixture of equal parts of alcohol and sulphuric 

 acid. It is the lightest known liquid substance, being 

 of specific gravity 632 at 60. Ij is. very volatile, and 

 rises in vapour even by the heat of the body. It is 

 highly inflammable. In the formation of ether it is 

 most probable that carbon and the elements of water 

 are separated from the alcohol, and that ether differs 

 from alcohol in containing less oxygene and carbon ; 

 but its composition has not yet been accurately ascer- 

 tained. Like alcohol it possesses intoxicating powers, 



A number of the changes taking place in the ve- 

 getable principles depend upon the separation of oxy- 

 gene and hydrogene as water from the compound ; 

 but there is one of very great importance, in which a 

 new combination of the elements of water is the prin- 

 cipal operation. This is in the manufacture of bread. 

 When any kind of flour, which consists principally of 



In the process of the distillation of alcohol and sulphuric acid after the ether 

 is procured ; by a higher degree of heat, a yellow fluid is produced, which is the 

 substance in question. It has a fragrant smell and an agreeable taste. 



