106 COMMON SENSE 
with crude petroleum laid on like paint. Of all the preservatives 
that we have ever tried, this is the cheapest and best.* 
Another important point—ventilation—was not forgotten. In 
cold winter weather, very little ventilation is needed, and I depended 
largely upon the cracks round the door and other openings to 
supply it. But cracks and openings are bad things, and to have 
left a crack at the bottom, and made a hole at the top, would have 
passed such a current of cold air over the fowls as might have 
produced frozen combs and wattles. To avoid this, three holes—2 
inches in diameter—were made along the front—that is at the 
highest part of the house. Under these holes was placed a thin 
board shelf, 14 inches wide, and during cold weather the space be- 
tween the shelf and the roof is packed with straw. ‘This, of course, 
puts a complete stop to all currents, but every chemist knows that 
through such porous packing the foul air will pass off by a process 
of “diffusion,” and pure air will enter from the outside even 
against a considerable current. Moreover, the straw acts like the 
“regenerator” in Ericsson’s first caloric engine, and absorbs the 
heat from the outgoing air to give it up to the incoming. 
I have described the house, as. we finally made it. . Before com- 
mitting myself to a particular pattern I made one myself, and hav- 
ing surrounded it with a yard of portable fencing, I put seven hens 
and a cock into it and tried it for a couple of weeks. I found a 
few points to modify in my first model, but the final outcome was 
as I have described and was very satisfactory. 
* Crude petroleum may be obtained at a very cheap rate by the barrel, and is 
easily applied. If too thick and sticky it may be thinned with benzine or gaso- 
line. When using it, great care must be taken not to allow a light to come 
near it, or the whole house would be in ablaze. We painted our houses out- 
side and in before we lined them with tarred paper, and one of them got pretty 
badly scorched, by a workman, who struck a match neat one to light hie pipe. 
Tt was a windy day and he stuck his head in to get shelter forthe match. It was 
the only time any one struck a match near these houses, as he got badly 
burned, the petroletim having been thinned with gasoline. After a few days 
the volatile matter passes off, and the petroleum sinks into the wood, rendering 
it hard, durable and very difficult to set on fire. Crude petroleum is death to in- 
sects. It will be along time before houses painted with this material will be 
infested with lice. i 
