RECENT ADVANCES IN SCIENCE 37 



by butyl alcohol. (3) Peptide anhydrides or diketopiperazines, 

 also extracted by butyl alcohol but separable from (2) by the 

 fact that they are insoluble in alcohol, whereas proline is 

 soluble. (4) Dicarboxylic acids not extracted by butyl alcohol ; 

 and (5) Diamino acids, likewise not extracted by butyl alcohol 

 but separable from dicarboxylic acids by phosphotungstic acid 

 and other methods. Considerably higher yields of many of 

 the amino acids were obtained by this method, as much as 

 8 per cent, of proline being obtained from caseinogen. More- 

 over, it has enabled the author to isolate two new cleavage pro- 

 ducts from caseinogen, namely, ^-hydroxy glutamic acid (COOH 

 CH (NH 2 )-CHOH-CH 2 COOH) and ^-iso-leucyl-^-valine anhy- 

 dride, a peptide of the formula 



(CH-3) 3 -CH-CH XNH . co/ CH-CH XC2 f| 5> 



It is possible by this method to obtain a dry, almost neutral 

 amino-acid mixture which might serve as a basis for nutrient 

 media, with or without the addition of tryptophan, and might 

 even be employed for dietetic purposes owing to the absence 

 from the mixture of most of those acids which give rise to 

 glucose in the diabetic organism. 



Boswell and Dickson (/. Amer. Chem. Soc. 191 8, 40, 1779) 

 have made the interesting observation that fused sodium oxide 

 is an active agent for effecting oxidations ; thus, for example, 

 carbon monoxide in contact with fused sodium hydroxide at 

 410-30 is oxidised to carbon dioxide, an equivalent quantity 

 of hydrogen being set free at the same time ; similarly, sodium 

 formate and sodium oxalate are oxidised almost quantitatively 

 to carbon dioxide with evolution of hydrogen at temperatures 

 of 275 and 290 respectively. This action is explained by 

 assuming that it is really the water present in the fusion which 

 acts as the oxidising agent, the caustic soda serving to break 

 up the water catalytically. It is also suggested that the 

 general reaction by which carboxyl is replaced by hydrogen on 

 fusion with caustic soda — as, for example, the production of 

 benzine from sodium benzoate — is likewise an example of 

 simultaneous oxidation and reduction by the hydrogen and 

 oxygen of water. 



The oxidation of organic compounds by silver oxide has 

 been the subject of investigation by Behrend and Dreyer 



