SOIL STERILIZATION 99 
gallons, but the weaker solutions do not seem to be 
effective against many other diseases. 
Application—There is universal agreement that one 
gallon of the solution should be applied to each cubic 
foot of soil in order to thoroughly saturate every particle. 
It may be applied by means of watering cans, sprayers, 
barrels with hose attachments, overhead system of water- 
ing, special devices and through the regular water pipes 
of the house, and at different times, if the soil does not 
absorb the solution promptly. 
The watering-can method is slow and tedious and 
should not be used except in small houses. Sometimes 
barrels are supported on trellises 5 or 6 feet above ground 
and bibs inserted for hose attachment. A frame 10 feet 
square may be shifted from place to place, and this will 
mark each area which should receive a barrel of the 
solution. In soils that do not absorb water rapidly it 
will be necessary to return to the same areas two or three 
times in order to apply the full amount and to avoid 
puddling the surface. 
The pipes used in the overhead system of watering 
have been employed sometimes, but the lack of uniform 
distribution is an objection to this plan. 
B. H. Thorne, in the 1909 Report of the Vegetable 
Growers’ Association of America, gives the following 
description of the formalin tank which is shown in 
Fig. 33: 
“In order to get the right proportions, run clear water through 
the tank into a barrel of known capacity and time it, then run water 
through the formalin tank under the same pressure as the water, 
regulating it by the valve at S until the formalin tank runs one pint 
of formalin to 25 gallons of water. The water tank should be at 
least ten times the capacity of the formalin tank in order to furnish 
air to take the place of the formalin used. 
“The apparatus should be pumped full of air before it is used. 
A bicycle pump attached at A will do it nicely. The mixture will 
