220 THE FLOATING-MATTER OF THE AIR. 



On the 6th of April five bulhs of beef-infusion were 

 subjected for three hours to the action of the Sprengel 

 pump and boiled for a minute afterwards. They all 

 remain brilliant. 



On the 7th of April five bulbs of mutton-infusion 

 were treated like the beef-bulbs, being exhausted for 

 three hours and boiled for a minute. All remain clear. 

 This experiment was repeated and confirmed on the 

 20th of April. 



On the 14th of April three bulbs of pork-infusion 

 were exhausted for four hours and boiled for a minute. 

 They all remain pellucid. 



On the I7th of April four bulbs of accurately neu- 

 tralized urine were exhausted for five hours and boiled 

 for a minute. Three of them remain bright ; one has 

 become cloudy. 



This does not exhaust the list of instances. Many 

 other infusions have been sterilized by this method since 

 the 17th of April. 



It is perfectly certain that in most, if not all, of 

 these cases 200 minutes' boiling would have proved in- 

 sufficient to sterilize the infusion if it had been supplied 

 with air. 



Here the question naturally arises : — What would 

 happen if the bulbs were exhausted and left unboiled ? 

 Probably with sufficiently perfect exhaustion all infu- 

 sions would be sterilized. But in the trials I have thus 

 far made some of the unboiled infusions have become 

 cloudy, while others have remained clear. Thus three 

 bulbs of mutton-infusion exhausted for four hours, two 

 bulbs of beef-infusion exhausted for three hours, four 

 bulbs of pork-infusion exhausted for four hours and left 

 unboiled remain as transparent and as free from life as 

 their boiled companions. Various other instances of 

 sterilization without boiling might be cited. On the 



