CHEMICAL CRITERIA OF ANAEROBIOSIS 15 



and absence of air, etc. In general, the basis laid by Lobry de 

 Bruyn (1895), Lobry de Bruyn and Van Ekenstein (1895, 1896, 

 1897) Nef (1907), Mathews (1909), Henderson (1911), Glattfeld 

 (1913), and others, indicates two groups of products resulting 

 from alkali treatment, first, isomers as a result of the action of 

 weak concentrations, low temperature, etc., and second, split 

 products as a result of stronger concentration and higher temper- 

 ature. Weak alkalis are transformative, strong alkalis destruc- 

 tive. The literature indicates clearly that glucose ionizes in 

 the presence of alkali as a weak acid, which can be readily shown 

 by colorimetric determination of the change in H"*" ion con- 

 centration of alkaline buffer solutions to which glucose is added. 

 Alkali upsets the stability of the molecule causing the formation 

 not only of all the possible isomers, but of metallic glucosates, 

 and sugars of one, two, thi-ee, four, and five carbon atoms as 

 well as oxy-acids. 



The fact that decolorization occurs in the presence of minute 

 quantities of alkalis might seem to speak strongly for some isomer 

 as responsible for decolorization. But since isomers as well as 

 the original sugar are destroyed by higher concentrations of 

 alkah and these decolorize more readily than low concentrations 

 we cannot entertain this idea seriously. Also the decolorization 

 of methylene blue in sunilar concentrations of glucose and levulose 

 depends upon identical concentrations of alkali; thus 0.1 per 

 cent solutions of these sugars were decolorized in n/800 NaOH 

 but not in n/1600 NaOH during ten minutes boiling. 



Similarly the temptation to explain the possible reduction of 

 alkaUnity in the test almost to the vanishing point, by increasing 

 the glucose content, as a result of the adulteration of glucose with 

 effective isomers or split products is checked by the observation 

 that even 20 per cent solutions of glucose without alkali fail to 

 decolorize methylene blue on prolonged boiling. 



On the other hand we are unable to exclude split products as 

 the effective agency when alkali is present. Methylene blue 

 solutions caramelized by boiling a few minutes in n/ 10 or stronger 

 NaOH, and, when neutralized or even slightly acidified, and 

 allowed to regain their color (yellow + blue = green), can be 



