M. Kolbe on Isethionic Acid. 47 



Glycocol, and its homologues alanine, leucine, &c, are derived 

 from the corresponding acids, acetic, propionic, and valerianic, 

 when an atom of amidogen replaces an atom of hydrogen. They 

 hence receive the name amidoacetic, amidopropionic, amido- 

 valerianic acids. In like manner Kolbe considers lactic acid to 

 be derived from carbonic acid by the replacement of an atom of 

 oxygen by an atom of peroxide of ethyle, or, as he calls it, 

 oxyethyle ; or it may also be regarded as propionic acid, in which 

 an atom of hydrogen in the replacing radical is replaced by per- 

 oxide of hydrogen. Kolbe gives to it the name oxypropionic 

 acid. The homologues glycolic and leucic acids have, of course, 

 a similar constitution. Their relations will be best apparent from 

 a comparison of their formulae. 



HO, C 9 H 3 (C 2 O 2 ) HO, C 4 H 5 (C 2 2 )0. 



Acetic acid. Propionic acid. 



HO 



C2 Sh*} < C * ° 2 )° H °' ° 4 NH 2 } C * ° 2 > °« 



Amidoacetic acid Amidopropionic acid 



(glycocol). (alanine). 



' ^ HO*} (C * ° 2)0 H °' ^ NH«} C * °*> °- 



Oxyacetic acid Oxypropionic acid 



(tact 



(glycolic acid). (lactic acid). 



The recent experiments on the conversion of lactic acid into 

 propionic acid* and into alanine, support these relations. 



In a similar manner Kolbe derives a series of bodies from an- 

 hydrous sulphuric acid, the formula of which he writes (S 2 4 ), O 2 , 

 that of the hydrated acid being 2 HO, (S 2 O 4 ) O 2 . Just as acetic 

 acid is methylcarbonic acid, so sulphomethylic acid is methylsul- 

 phuric acid. 



HO, C 2 H 3 (C 2 2 ) HO, C 2 H 3 (S 2 O 4 ) O. 



Methylcarbonic acid Methylsulphuric acid, 



(acetic acid). 



Isethionic acid stands in the same relation to sulphovinic acid 

 as lactic acid to carbovinic acid. And as lactic acid is carbonic 

 acid in which an atom of peroxide of ethyle replaces an atom of 

 extra-radical oxygen, so isethionic acid is derived from sulphuric 

 acid by the substitution of an atom of oxygen for an atom of 

 extra-radical oxygen. Kolbe adduces, in support of these views, 

 some experiments which he has made with isethionic acid. When 

 isethionate of potash is distilled with pentachloride of phosphorus, 



p4 TT41 



a compound, ™ > (S 2 O 4 ) CI, corresponding to chloride of lac- 

 * Phil. Mag. vol. xix. p. 384. 



