MATERIALS 43 



one which contains only a small proportion, either 

 of the very volatile, or very stable paraffins. One of 

 the various products known as solar distillates has 

 been found to answer these requirements, and is sold 

 under the name of the Woburn Distillate. Ordinary 

 paraffin lighting-oil will answer most purposes fairly 

 well, but the solar distillate, besides being more 

 efficient, possesses the further advantage of being 

 cheaper, of not being an "inflammable" for the 

 purposes of railway carriage, and of emulsifying 

 well with the basic sulphates of iron and copper, 

 whereas lighting-oil is less satisfactory in this 

 respect. 



Paraffin is sometimes sprayed on to dormant trees 

 as a winter wash ; but it cannot be recommended for 

 this purpose. It has little or no detergent action as 

 regards moss, lichen, etc., and it is less effective in 

 destroying mussel scale, etc., than is a caustic wash 

 to which 6 per cent, of paraffin has been added. It 

 is also liable to injure the trees, especially if used in 

 successive years, the buds and tips of the shoots 

 being destroyed. The heavier the oil, the more 

 marked is this destructive action. 



Young nursery stock may be immersed in petrol 

 before planting for the destruction of woolly aphis, 

 and this treatment has not been found to result in 

 any injury to them : but no less volatile oil should be 

 us-ed for this purpose : even a good quality lighting- 

 oil, such as White Rose, has been found to have a 

 very deleterious effect on the trees ; and the use of 

 a heavy oil, such as solar distillate, will prove fatal. 



Apple trees may be effectively sprayed in summer 



