Great Britain and Ireland. 31 



intermediate between 212° and 172°; the boiling point 

 being higher or lower, as the proportion of water in the 

 mixture is greater or smaller. 



3. When the steam of water is thrown into, or blown 

 through a liquid composed of water and alcohol, this 

 steam will be condensed until it has given out heat enough 

 to raise the mixture to its own boiling point, after which a 

 portion of alcohol is volatilized and thrown off in vapour, 

 by the further application of steam to the mixture. 



4. When a mixture of steam and alcoholic vapour is blown 

 through a liquid composed of water and alcohol, similar 

 effects are produced ; for, after the liquid mixture has 

 arrived at its boiling point, the vapour blown through it 

 lets go some of its watery part, or steam, and an equivalent 

 quantity of alcohol is volatilized, and the mixed vapour, 

 after passing through the liquid, carries off a larger pro- 

 portion of alcohol than it brought with it. 



5. When a mixture of steam and alcoholic vapour passes 

 into a condenser, or worm, the vapours first condensed will 

 contain more than a mean proportion of steam, or watery 

 vapour; and, if the size of the condenser, or worm, be not 

 sufficient, or the temperature of the bath in which it is 

 immersed be too high to condense all the vapour, that 

 portion of it which escapes uncondensed will contain more 

 alcohol than the portion condensed. 



Requesting our readers to keep these premises in mind, 

 we shall now proceed to the description of Mr. Coffey's 

 apparatus, in which, as we have already said, they are all 

 brought into action. 



The body of the apparatus consists of an oblong vessel, 

 BB , and two columns erected thereon, C, D, E, F, and 

 G,H,I,K,. 



The first of these columns is called the analyzer, the 

 second the rectifier. 



The whole is made of wood, lined with copper, and the 

 wood being five or six inches thick, little or no heat is lost 

 by radiation. 



The oblong vessel has a copper plate or diaphragm c d 

 across the middle of it, which divides it into two chambers 

 B B'. This diaphragm is perforated by a great number of 

 small holes, for the passage of the vapour upwards durin» 



