136 The Spraying of Plants. 



CHLORIDE OF COPPER. See COPPER CHLORIDE. 



CHLORIDE OF IRON. See IRON CHLORIDE. 



CLAY. See WASHES. 



COAL TAR. If a few quarts of coal tar are added to a barrel 

 of water, the liquid soon becomes so impregnated with the odor 

 that it may be used as a repellent of insects. A strong solution 

 of gas tar may be used for a similar purpose, but these applica- 

 tions possess comparatively little value. 



COMBINATIONS OF INSECTICIDES AND FUNGICIDES. The 

 most successful of these combinations is that of the Bordeaux 

 mixture and compounds of arsenic. The lime in the mixture 

 prevents the arsenic from injuring foliage, while it does not 

 appear to lessen the efficiency of the poison. Each preparation 

 is applied at the same rate as if used alone. 



A combination of the ammoniacal carbonate of copper and 

 an arsenite has been used with success by some, but such a 

 preparation is frequently very injurious to foliage, and it 

 should be applied with caution. The ammonia acts as a 

 solvent of the arsenic, and this solution does the damage. 

 The addition of lime would tend to reduce the severity of 

 the injury. 



The Bordeaux mixture has been used as an agent for emulsi- 

 fying kerosene, with apparently satisfactory results. 1 The 

 preparation should be more thoroughly tested before it can 

 be recommended. Kerosene emulsion and Bordeaux mixture 

 have been combined, but not with satisfactory results. See 

 also CORNELL MIXTURE. 



When pure kerosene is emulsified with the Bordeaux mixture, 

 the combination allows the addition of Paris green, making 

 a mixture adapted to destroy nearly all the insect and fungous 

 enemies of plant life. When a mixture of kerosene emulsion 

 and the Bordeaux mixture is made, the arsenite cannot be 

 added successfully; for even when the emulsion and the arsen- 

 ite are united, the resulting mixture is still unsatisfactory. 



Resin washes and kerosene emulsion, applied together, have 

 not yet been sufficiently studied and tested to determine the 

 value of such mixtures. 



A simple solution of resin, made as described on page 169, is 



1 See Galloway, Insect Life, vii. 126, for an account of this and other com- 

 binations. 



