1918] CURRENT LITERATURE 179 
leaves in solution a quantity of sodium acetate sufficient to practically inhibit 
inversion by 2 per cent acid. The authors find that 10 minutes’ boiling with 
ro per cent citric acid completely hydrolyzes cane sugar without affecting 
maltose or decomposing pentoses, and recommend this method. Inversion 
by invertase also gave quantitative results which were too low, apparently, 
because maltose is carried down in the precipitation with alumina cream. It 
was impossible to estimate maltose in plant extracts by hydrolysis for 3 hours 
with dilute boiling HCl or H.SO,, as recommended by BROwN and Morris, 
since there was destruction of at least 30 per cent of the levulose present, with 
measurable amounts of dextrose, by such treatment with any concentration of 
acid sufficient to effect complete hydrolysis of the maltose present. Hydrolysis 
with 2.44 per cent HCl at 70° gave no better results; in a 1 per cent solution 
only 94 per cent of the maltose had been converted after 24 hours’ boiling and 
there had been material destruction of the levulose present. The authors 
therefore adopted fermentation of the maltose-containing solution with pure 
cultures of maltose-free yeast as the only satisfactory procedure. The solution 
is freed of tannins, amino acids, etc., with basic lead acetate, is then made 
lead-free by adding solid Na.CO,, issn ge: treating with H.S, an 
finally making slightly acid to litmus with dilute Na,CO;. Three _— 
Saccharomyces exiguus, S. anomalus, and S. marxianus, were used, the ferm 
tation being continued at 25° for 31 days. All gave good results, but S. exiguus 
is best for general use, since it is least sensitive to acid and its less bulky growth 
causes less contamination of the cuprous oxide precipitate with salts of amino 
acids. Checks fermented with ordinary distillery yeasts permit the making 
of a correction for pentoses remaining after the other sugars have been 
destroyed. Pentoses were determined by distillation of an aliquot of the 
solution with HCl at 70° and weighing the furfural as phloroglucide. 
authors’ assertion that maltose is hydrolyzed by HCl at 70° has been 
questioned by Kiuyver, and Davis has consequently presented further 
evidence’ by reporting the results of a series of experiments with a 1 per cent 
solution of maltose, carried out under exact Herzfeld conditions, which show a 
rather uniform loss by hydrolysis of about 2 per cent of the maltose present. 
he authors present a scheme for the analysis of plant extracts which 
may be summarized as follows. The extract is evaporated to small volume in 
The remainder of the solution is treated with basic lead acetate, filtered, and 
made up to 2000 cc. A portion of this is freed of lead, made up to convenient 
‘ Kievves, A. J., Biochemische Suikerbepalingen. pp. 223. Boekhandlung 
E. J. Brill, tdiden, 1914. 
§ Davis, WittraM A., The hydrolysis of maltose by hydrochloric acid under the 
Herzfeld conditions of inversion. A reply to A. J. Kiuyver. Jour. Agric. Sci. 
6:413-416. 1914. 
