39 
fungus were observed to be growing on the surface of the 
one inside the house, which soon developed into 4 or 5 little 
buttons of fungus. I considered that the spores which 
had fallen on this flour paste must have been sticking to the 
sides or roof of the room, and to eliminate this assumed 
cause of error, I drew out the supporting rods of the room 
and crushed it up and boiled it in water for half an hour, 
then allowed it to dry and repeated the same experiments 
with the two basins of flour paste, the bellows being first 
worked and the glass then tafken out and laid down in the 
ordinary or contaminated air, then wiped with a clean 
cloth and put in. In a few days afterwards, the paste 
outside the house was completely covered with fungus, 
whilst the one inside was absolutely free from it, and it re- 
mained free for nearly a month, when one little speck was 
observed on it which soon developed into a little button of 
fungus. This showed that for three weeks after the paste 
was placed in the room no spore had fallen on it. The only 
cause of failure I could see was the glass, upon which some 
spores must have adhered, consequently I had a bag made 
and sewn on above the window, into which the glass could 
be pulled in opening the window. When this was done the 
house was again crushed up and boiled in water, again placed 
in position, the paste boiled, the window closed, and in this 
third trial the experiment was perfect. No fungus was de- 
veloped on the paste inside the house, and after some months 
it dried up to a hard mass. Thus these thin sheets of cotton 
wool forming a room of 10,032 cubic inches capacity, i.e., 
capable of holding 36 gallons of air, was sufficient to prevent 
the entrance of spores into it, and thus to preserve the flour 
paste from decomposition during several months, till it had 
completely dried up. 
These results, I think, conclusively shew that ordinary 
large rooms may be constructed and ventilated with filtered 
air, by means of fans, so that flour paste, taken as a test 
