134 THE EVOLUTION OF LIFE 
Some preliminary experiments were made with 
an apparatus closely similar to that employed by 
W. Roberts in the very few experiments which he 
: undertook with hay-infusion. 
Small narrow-necked flasks 
were taken capable of hold- 
ing nearly 3 oz. of fluid; 
and each of these was about 
half filled with a measured 
amount of fresh unfiltered 
urine, whose degree of acid- 
ity had been previously as- 
certained by carefully finding 
the exact number of minims 
of the liquor potassz of the 
‘‘ British = Pharmacopeoeia” 
which were needed to neutra- 
lise one ounce of it. Quan- 
tities of liquor potassze, just 
sufficient to neutralise the 
amount of urine intended 
for each flask, were then 
bead & enclosed in a number of 
Plugged Flask with liquor-potassze glass tubes, each of which 
tube. had a small bulb at one ex- 
tremity, and a similar bulb near the other end, beyond 
which it was drawn out asa thin prolongation and bent 
at an obtuse angle. Each of these tubes was charged 
1 It may be well to mention that the solution of potash above named 
has a sp. gr. of 1058, and that it contains 27 grains of caustic potash 
to the fluid-ounce of water (5.84 per cent.). What I have used has 
always been purchased from Mr Martindale, of 10 New Cavendish 
Street, London. 





