'263 



and on the surface of the neck with the aid of a dropping syringe. 

 The size of this drop is to be regulated by the quantity of sugar to be 

 fermented. This quantity ouglit not to surpass 3.5 mgr. and practi- 

 cally not to sink under 0,1 mgr. The concentration of the solution 

 should be more than 0,47o. Good results are to be had with a 

 37o sugar solution, from which it is best to take drops of 0,06 — 

 0,08 cc. 



After this the funnel is carefully lowered ; thereby the drop of 

 liquid is drawn into the apparatus. This can be performed without 

 any loss of liquid, if only the paraffin cover have been laid down in 

 the right way on the neck of llie reservoir. Should however any 

 liquid be left behind, then this has to be removed with a small 

 piece of filter-paper. 



The meniscus of the solution in the upper part of the neck will 

 be convex, especially when some paraffine iiad been brought along the 

 inner side of the neck. This siiape of ihe meniscus can be obtained 

 in the best way by making the solution rise from a lower part of 

 the neck up to the top, taUing care however, not to have it lowered 

 under ihe narrow part. In this way it is possible to bring the 

 tangent-plane at the meniscus on the level of the upper surface of 

 the neck. After fixing the apparatus in this position, the 2'"^ readiny 

 of the meniscus of the mercury in the straight capillary glass tube 

 is made. 



The difference between the two first readings gives: the volume 

 of the sugar solution to an accuracy of 0,001 cc. 



Now again the liquid is a bit lowered, but not so far as to reach 

 the narrow part. Then, with a thiii capillary glass tube, we add a drop 

 of yeast-suspension, which has been prepared previously as already 

 indicated. The drop is carefully thrown into the apparatus, until the 

 meniscus, whicli again will be convex, reaches the same level as 

 mentioned before. Now the 3"h-t'(uli.ng is taken. 



The dilference between the 3rd. and the 2nd. reading gives: the 

 volume of the added yeast-suspension. Cai-e must be taken that to 

 1 part of sugar about from 5 to 8 parts of yeast be added (weighed in 

 living stale) ^). With sugar concentrations of about 3 per cent and with 

 suspensions of yeast, prepared in the described way, this can be 

 done by taking the volume of the suspension nearly the same as that 

 of the sugar solution. 



After this 3rd. reading the licjuid is allowed to go down to the 

 narrow part of the neck; tiiere the meniscus will be decidedly con- 



1) Just by the choice of these large quantities of yeast, the ferraenl:ition-time 

 is much reduced. coinp;ireil wilh tlic (hiralion of the analysis, made by Kluyvur. 



18* 



