104 ACCESSORIES 
readily, are satisfactory. Iron tanks are somewhat objectionable 
because if copper compounds, such as Bordeaux mixture or copper 
sulphate solution, are used in such tanks, the chemicals will tend to 
break down. Other chemicals have a corroding action on the iron. 
Mixing Tanks 
Where extensive spraying is carried on it is convenient and desirable 
to provide suitable mixing tanks elevated on a stout platform. By 
this means much valuable time will be saved in the preparation of 
materials. In addition, the work of spraying can be completed more 
promptly, the materials applied when they will do the most good, and 
advantage taken of favorable weather conditions. 
The design of a mixing plant will depend on the nature of the work to 
be done, the amount of work, the topography of the location, the source 
of water supply, and like matters. The general principles governing 
its design are the provision of an adequate supply of stock solution, 
convenience in mixing, and the utilization of gravity in transferring 
liquids from stock tanks to mixing tanks, and from the latter to the 
spray tank. Expensive and troublesome outlet valves may be avoided 
by using a section of large diameter hose, the free end of which may be 
fastened up above the level of the liquid in the tank. 
