18 



DE. BASTIAI^ ON THE 



much doubt), there would be an end to the long-established reput 

 tion of cotton- wool as a protective filter in such experiments. 



To get rid, however, of all doubt -pig 8. 



of this kind, I determined to repeat 

 the urine and liquor-potassse expe- 

 riments with hermetically sealed 

 vessels from which air had been ex- 

 pelled by boiling, and to take the 

 further precaution of boiling the 

 liquor-potassse tubes before insert- 

 ing them into the experimental ves- 

 sels. It was safe at once to resort 

 to such a method, because I had 

 previously ascertained that urine 

 neutralized before boiling would fer- 

 ment in such closed airless vessels 

 almost, though not quite, as freely 

 as in flasks plugged with cotton- 

 wool. There was, therefore, nothing 

 unduly restrictive in the proposed 

 conditions. 



The new mode of procedure which 

 I devised was conducted as fol- 

 lows : — 



In the first place a stock of liquor- 

 potassae tubes had to be prepared 

 beforehand containing convenient 

 amounts of liquor potassaB. Some 

 were charged with 8, others with 10, 

 and others with 12 or more minims. 

 Those containing the same quantity 

 were kept together in separate 

 batches duly labelled and ready for 

 use, as occasion required, according 

 to the degree of acidity of the urine 

 with which experiment was to be 

 made. In order to ensure perfect 

 accuracy in the measurement of the 

 liquor potassse, T have of late made 



use of a small burette-tube (fig. 3) Burette-tube for measuring 

 graduated to minims and fitted with liquor potassge. 



