174 
PROFESSOR TYNDALL ON THE DEPORTMENT AND VITAL 
§ 15. Experiments on the Roof of the Royal Institution. 
With a view to making nearer home experiments similar to those made at Kew, I 
had a wooden shed erected on the roof of our laboratory. The shed was provided with 
benches, water and gas-pipes, and a stove for heating. To an infusion of cucumber, 
which I had found extremely intractable in the laboratory, my attention was first 
directed. Two tin chambers of three tubes each were prepared, and transferred to 
the shed from the workshop where they were made without being permitted to enter 
our laboratory. The cucumber used for the infusion was also kept clear of the infected 
air ; it was sliced and digested in the shed, the infusion was there filtered, introduced 
into the tin chambers, and boiled subsequently for five minutes. 
The result was not that expected. Not a single tube of either of these two chambers 
escaped contamination. They one and all behaved like the same infusion in the 
infected laboratory, becoming in three days turbid throughout and laden with fatty 
scum. 
I have been daily and hourly impressed with the parallelism between these pheno- 
mena of putrefaction and those of infectious disease. A further illustration of this 
parallelism is here presented to us. The clothes of my assistants who prepared the 
infusion in the shed had been worn in the laboratory, a transfer of infection by one of 
the modes of transfer known to every physician being the result. The thoughtful 
physician cannot indeed fail to see the absolute identity of deportment between the 
contagia with which he is familiar, and those assailants of my infusions against which I 
have been contending so long. 
With regard to the shed my first step, after this preliminary failure, was to disinfect 
it. This was done by washing every part of it, first with a mixture of carbolic acid 
and water, and secondly with a solution of caustic potash. When the whole was well 
dried, new tin chambers furnished with new tubes were introduced. Cucumbers and 
beef fresh from the market were also digested in the shed, my assistant taking care to 
cover his legs with clean linen trowsers, and his body with a new blouse. There was 
one chamber devoted to the cucumber and another to the beef. Into the former the 
infusion was introduced on the 19th, and into the latter on the 20th of March; each 
infusion was boiled for five minutes after its introduction. 
Let us compare results and draw conclusions. At a distance of eight yards from the 
shed, viz. in the laboratory, infusions both of beef and cucumber refuse to be sterilized 
by three hours’ boiling. Indeed I have samples of both infusions which have borne five 
hours’ boiling and developed multitudinous life afterwards. But the upshot of this 
experiment in the disinfected shed is, that every tube of the two chambers, though 
boiled for only five minutes, contains an infusion which, at the present hour, is as limpid 
as the purest distilled water. 
What shall we say, then \ is the infusion in the laboratory endowed with a generative 
force denied to the same infusion in the shed ? Irrespective of the condition of the air, 
can a linear space of eight yards produce so remarkable a difference 1 It is only the 
