VITALITY OF PUTKEFACTIVE OKGANISMS. 155 



occurred to me of soaking the hay for some days prior 

 to digesting it. Old London hay was accordingly 

 chopped up and placed in three glass vessels — one con- 

 taining distilled water, another acidulated water, and a 

 third alkalized water. The superior extractive power 

 of the alkalized liquid was at once manifest ; it rapidly 

 assumed a dark colour. The distilled water came next, 

 yielding a colour less deep than that of the alkalized, 

 but more deep than that of the acidulated water. The 

 alkaline and distilled-water infusions emitted a rich 

 odour of hay, while the smell of the acid infusion was 

 very faint, and not like that of hay. The hay was per- 

 mitted to soak from the 8th to the 1 1th of November. 

 It was then digested for three hours in the same liquid 

 at a temperature of 120° F., boiled, filtered, and intro- 

 duced into the clospd chambers, where it was reboiled in 

 each case for five minutes. 



Prior to digesting the hay in the liquid in which it 

 had been soaked, Bacteria had developed in swarms. 

 These, of course, were killed by the boiling, and they 

 were not entirely removed by the filtration. The alka- 

 line infusion, indeed, though filtered repeatedly, was 

 sufficiently turbid to prevent the flame of a candle 

 placed behind the tubes containing it from being seen. 

 The same to a less extent was true of the distilled- 

 water infusion. This latter had been divided into two 

 portions, one of which was accurately neutralized, and 

 the other left unneutralized, a separate chamber being 

 devoted to each. 



From the 11th to the 18th of November the only 

 change observed in any of the infusions was in the 

 direction of increased transparency. They all became 

 clearer with time, the distilled-water infusions becoming 

 particularly clear and brilliant at the top. After two or 

 three days' quiet the alkaline infusion allowed a flame 



