COMBINED SPRAYS FOR CONTROLLING INSECT PESTS. 
compound in Bordeaux by using potassium ferrocyanide (the bright 
iron blade is not reliable and the other test is simple); the test for 
arsenate of soda in lead arsenate, by using lead acetate solution; and 
how to test for acids and alkalies. 
He should also demand from the supplier full information about 
the preparations, such as the percentage of nicotine in a tobacco extract; 
the nature of the lead arsenate, whether neutral or acid; the absence 
of free arsenic or arsenate of soda in lead arsenates; the percentage 
of polysulphides in lime sulphur solution, &e, 
In order to assist the man on the land the accompanying chart has 
been prepared, and will show at a glance what preparations can be 
mixed. 
In the central circle I have placed the two insecticides, arsenate of 
lead for biting insects, and nicotine for sucking insects. The chart 
should be read in any direction radiating out from the centre, and those 
Preparations adjacent in a radial. position can be combined without one 
or other of the constituents being altered to any great extent, or their 
efiiciency reduced. ue. 
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