CONDITIONS FAYOTJRING FERMENTATION. 



35 



albumen present would be precipitated when, or even before, the 

 temperature of the fluid was raised to the boiling-point. Or a 

 similar result miglit have been induced by the addition of a small 

 quantity of acid to a portion of a neutral or alkaline albuminous 

 urine which has just been boiled without a precipitation of the 

 albumen having been brought about. Thus the addition or pre- 

 sence of a small quantity of acid, in conjunction with an elevated 

 temperature, is seen to be capable of bringing about results which 

 cannot be produced by the mere elevated temperature alone." 

 Therefore it happens that the difference naturally existing 

 between the fermentability of the same fluid in a neutral and in 

 its acid condition is often notably intensified after boiling*. 



This difi'erence of eflfect produced by boiling acid and faintly 

 alkaline fluids respectively may, however, be only in part due 

 to the cause above indicated. Another factor comes into play 

 which may be even more influential; and that is, that the 

 boiling-point of the two liquids is difterent. Thus I find that 

 neutralized urine not only boils with more frothing, but also 

 at a decidedly lower temperature, than some of the same fluid 

 in its acid state. The neutral fluid will boil in a retort with a 

 capillary extremity at 99*8° C. ; and it must be boiled gently on 

 account of the frothing and tendency to spurt over ; but some of 

 the same fluid in its acid state will reach a temperature of 103° 

 or 108^° C. easily. In the same vessel distilled water briskly 

 boiled reached a temperature of 108° C. ; so that the boiling-point 

 of the neutral infusion is, by reason of its neutralization, decidedly 

 lowered f. 



Such a difference in temperature, therefore, may produce a very 

 marked difference in the total eff'ects of the boiling process in the 

 neutral and in the acid infusions respectively ; and these diffe- 

 rences will be more marked in some cases than in others, accord- 

 ing to the briskness of the ebullition of the acid fluid. I have seen 

 this point w^ell exemplified in more than one instance of late when 

 dealing with a urine of rather low acidity from which phosphates 



* See ' The Beginnings of Life,' vol. i. pp. 394-396. 



t These comparative trials were made with the same quantities of the diffe- 

 rent fluids placed in a rather wide-mouthed retort, with a small maximum- 

 thermometer whose bulb was kept away from contact with the glass. To the 

 neck of the retort was fitted in each case, by means of a piece of india-rubber 

 tubing, the same drawn-out neck. The comparison in the different trials was 

 therefore thoroughly accurate. 



3* 



