VITALITY OF PUTEEFACTIVE OBaANISMS. 175 



nificence of Mr. Jodrell, a new and very complete labo- 

 ratory had been just erected there, and in it I sought a 

 purer air than I could find at home. 



My chambers hitherto had been constructed of wood, 

 but those to be tested at Kew were made of block-tin, 

 and they were carried direct from the tinman's to the 

 gardens without being permitted to come near the in- 

 fected air of Albemarle Street. At Kew the test-tubes 

 employed were first cleansed with carbolic acid, then 

 washed with a solution of caustic potash, afterwards 

 swept out with distilled water, and finally raised almost 

 to the temperature of redness by a Bunsen-flame. They 

 were then fitted air-tight into the chambers with white- 

 lead and tow. 



The chambers were closed on the 3rd of January, 

 and allowed to remain quiet until the 8th, when the 

 two most refractory liquids that I had encountered in 

 the laboratory of the Eoyal Institution were introduced 

 into them. These were infusions of cucumber and 

 melon. There were two chambers devoted to each 

 infusion — four in all ; and each chamber embraced three 

 large test-tubes. The period of boiling was that found 

 eifectual last year, i.e. five minutes. The temperature 

 of the room in which the chambers were placed was 

 maintained, partly by hot-water pipes and partly by a 

 gas-stove, at about 90° Fahr. — a temperature which had 

 been proved eminently favourable to the development of 

 Bacteria. 



Tubes containing the same infusions were at the same 

 time exposed to the common air of the Jodrell labora- 

 tory. These became rapidly turbid and covered with 

 scum. My interest and anxiety during the early days 

 of the trial of the protected tubes may be imagined. 

 After eleven days' exposure they showed no signs of 

 giving way. On the 1 9th of January the four chambers 



