156 THE EVOLUTION OF LIFE 

Comptes Rendus for January 8, 1877, a communication 
appeared from MM. Pasteur and Joubert,! saying 
they had again gone carefully over the questions in 
dispute, but that for the present they wished the 
discussion limited to the one point, whether pure 
solid potash or a potash solution heated to 100° C. 
would fertilise boiled urine. They still implied that — 
living germs were contained in boiled liquor 
potasse ; and in reference to his own negative 
results, Pasteur said the question is limited to this— 
Have I passed the point of saturation (that is, made 
the urine “alkaline”), and if so, is there any harm 
in so doing? 
On January 22 I could only reiterate what I 
had said before: that the use of solid potash was 
altogether unnecessary ; that the solution could be 
easily heated to 110° C. and would act just as if it 
had been heated only to 1oo° C., when in suitable 
quantity ; that there was absolutely no evidence of 
the existence of living germs in liquor potassz heated 
to 100 C.,? and the proof of this was that too much 
or too little potash contained in the tubes had no 
fertilising effect. That was the proof of my position, 
though he could produce no independent evidence 
of a contrary kind. Of course, if the boiled liquor 
potasseze contained living germs, one or two drops 
of it would act just like tap water and contaminate 
1 The latter being Professor of Physics in the College Rollin. His 
help was also acknowledged by Pasteur in his first reply to me. 
2 Or in the air contained with the boiled potash tubes, which was 
what Wm. Roberts suggested. It was this supposition that led him to 
advise their superheating. He did not venture to suggest that germs 
could survive in the boiling liquor potasse ! 
