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Separation of the Isomeric Amylic Alcohols. [Feb. 25, 



II. " Note on the Separation of the Isomeric Amylic Alcohols 

 formed by Fermentation." By Ernest T. Chapmax and 

 Miles H. Smith. Communicated by Prof. E. W. Brayley. 

 Received January 14, 1869. 



At present we are acquainted with two amylic alcohols formed by fer- 

 mentation. They were discovered by Pasteur, who observed that different 

 specimens of amylic alcohol caused a ray of polarized light to rotate to dif- 

 ferent degrees. He succeeded in devising a separation of these alcohols, 

 which consisted in converting them into sulphamylates of barium and re- 

 crystallizing these salts. The one alcohol is without action on polarized 

 light, and the other rotates it. This method of separation is beset with 

 great practical difficulties > and has, we believe, only once been repeated, 

 viz. by Mr. Pedler. He gives no detailed account of the separation, but 

 gives some of the leading properties of the alcohols. He found that the 

 rotating alcohol caused a ray of polarized light to rotate 1/° with a column 

 of 500 millims. of liquid. 



The following are some examples of the rotations effected by eleven dif- 

 ferent samples of amylic alcohol in a column of 385 millims. For compa- 

 rison with Pedler's number, the observed numbers have been reduced in the 

 second column to observations on 500 millims. : — 



Designation of 

 specimen. 



Rotation observed on 

 column of 385 millims. 



Seduced to observations 

 on 500 millims. 



1. 



o 



35 



4-55 



2. 



37 



4-81 



3. 



4 



5-2 



4. 



37 



4-81 



5. 



4-7 



6-11 



6. 



4 



5-2 



7. 



3-5 



4-55 



8. 



27 



3-51 



9. 



5 



6-5 



10. 



4 



5-2 



11. 



3-8 



494 





170 





If Pedler's number be absolutely correct, it follows that these specimens 

 of amylic alcohol contained from 15 "9 per cent, as a minimum, to 38*2 as 

 a maximum of the rotating alcohol. The boiling-points of the whole of 

 the samples lay between 13i°-5 and 133°. 



We have effected the separation of these alcohols more simply. If soda, 

 potash, chloride of calcium, or, apparently, any salt easily soluble in amylic 

 alcohol be dissolved in that alcohol at the boiling-point, and the saturated 

 solution be distilled, the non-rotating alcohol will be to a great extent re- 

 tained and the rotating alcohol distils off. The substance which appears 

 to lend itself most conveniently to this operation is caustic soda. 



Amylic alcohol is boiled with excess of caustic soda ; when saturated, 



