or 
TRANSACTIONS OF SECTION B. 711 
the matter which diffused, and that remaining in the dialyser was the same as that 
in the mixture where no dialysis was possible. 
Other experiments showed that no increased diastatic action took place in the 
presence of yeast, if the fermentative power of the latter was checked by chloro- 
form, neither was any increase of action observed when the malt extract was 
fermented and the yeast removed before the starch-granules were added. It 
appears, therefore, that it is necessary to have both the diastase and the yeast 
present together in a condition capable of exercising their respective functions, in 
order to obtain the increased action. 
Precipitated diastase acts in the same way as cold-water malt extract. 
The combined action of diastase and yeast on starch-granules differs from that 
of the two on the so-called stable dextrin, since it only takes place on those 
starches which are attacked in the ungelatinised form by diastase, such as barley 
or malt starch. The granules of potato starch are not acted on by diastase, even 
in the presence of yeast. 
4. The Action of Acids on Starch. By G. Harris Morris, Ph.D., LLC. 
Some months ago, H. Johnson! published a paper in which he maintains that 
when starch is hydrolysed by acids only dextrose and dextrin are produced, and 
that under no conditions is maltose formed in the reaction. He also adopts the 
view that glucoamylins are formed in the reaction; these substances he regards 
as molecular aggregates of dextrose and dextrin, similar to amyloins or malto- 
dextrins, but containing the dextrose in place of the maltose group. 
This view of the acid hydrolysis of starch is opposed to that previously held by 
the majority of observers, and is completely at variance with the results obtained 
by Rolfe and Defren, and the author’s. 
Johnson states that the properties of the substances intermediate between starch 
and dextrose can be expressed in terms of dextrin and dextrose, and that when 
this is done the specific rotatory power calculated for such a mixture agrees with 
the observed angle for the conversion. He supports this view by giving results 
obtained with acid starch conversions and with fractions of such conversions ob- 
tained by precipitation with alcohol. 
Johnson also states that the action of diastase on the products of the acid 
hydrolysis of starch is very slight, thus further proving the different nature of the 
products intermediate between dextrin and dextrose from those of conversions with 
diastase. 
The author’s experience is, however, directly opposed to that of Johnson. A 
large number of acid starch conversions, analysed and calculated in the manner 
described by the latter, gave differences between the observed and calculated specific 
rotatory powers corresponding to the presence of from 5 to 45 per cent. of maltose. 
The examination of alcoholic fractions gave similar results, and from the fractions, 
the analysis of which indicated the presence of considerable percentages of maltose, 
erystals of undoubted maltosazone were obtained. 
The results of the action of malt extract were also entirely different from those 
obtained by Johnson, the fall in angle on degradation amounting on an average 
to more than 20° [a]p, 
The author’s results were obtained from conversions made with different 
starches and acids, and under varying conditions of temperature and pressure, and 
in nearly all cases the analytical data, when calculated in the manner indicated 
above, showed a difference of angles, indicating the presence of maltose. 
Several of Rolfe and Defren’s results were also calculated in the manner adopted 
by Johnson, and it was found that they fully confirmed those of the author. 
The author also criticised the law regarding the products of acid hydrolysis of 
starch at which Rolfe and Defren had arrived, and he considered that owing to 
the method of calculation accepted, further investigation was required before it 
could be employed. 
» Trans. Chem. Soc. 1898, pp. 490-502. 
