( 1205 ) 
the presence of alkali, in this case ammoniumcarbonate, and it is 
most effective when the medium titrates about '/,, N alkali. 
It is obvious from the above tables that the action of the lipase 
depends on the concentration of the hydrogen and of the hydroxylions, 
the former exerting a retarding, the latter an accelerating influence. 
From these observations it follows that rancidity of dairy products 
can only then be caused by lipase when the acid degree of these 
products is below '/,, N. This will be the case when the lactic 
acid in butter or cheese, which at first exceeds by far the said 
concentration, has lowered to '/,, N, through the action of alkali- 
producing bacteria and moulds; they neutralise and oxidise the 
present acid, whilst besides, by the formation of calciumcarbonate 
by the oxidation of calciumlactate, acid is also neutralised. 
Influence of various compounds on the fat-splitting by 
microbie lipase. 
It was found of importance to consider in how far other com- 
pounds than acids and bases act on fat-splitting by lipase. For 
these experiments it is desirable to work with a lipase prepar- 
ation, which, besides the enzyme, contains no or only extremely 
small quantities of compounds that might act on the splitting-process. 
Such a preparation is satisfactorily obtained by dialysis of the 
medium whereon the lipase-microbe has grown or by precipitation 
of the enzyme from it. 
Dialysis of the microbic culture proceeds very slowly, so that it 
must be continued some weeks, when parchment paper dialysators 
are used, before the dialisable compounds are sufficiently diluted to 
make the experiments succeed. 
The results obtained with such a lipase preparation are to my 
opinion not quite trustworthy as during the long time of the 
dialysis number of processes may go on in the complex culture 
liquid. By means of greased tubes, however, it could be stated that 
the fat-splitting power of the culture decreases during the dialysis, 
the dialysate containing no lipase or only very small quantities. 
When the dialysate is again added to the dialised culture, the fat- 
splitting power of the mixture is greater than that of the culture to 
which as great a volume of water has been added as in the 
previous case c.c. dialysate; it was also found that slight quantities 
of calcium and magnesium salts act favourably on the decomposition. 
It is possible in a very short time to procure a microbic-lipase 
preparation, quite answering the said requirements and which 
