xxxviii Remedial Measures and Insecticides. 



prolonged boiling. The wash itself is practically a sulphide of 

 lime, with much free lime and salt carried with it. Prolonged 

 boiling will result in taking up temporarily additional sulphur, and 

 will perhaps add to its caustic properties if it is applied very hot ; 

 on cooling, however, it reverts to the simpler tri- or bi- sulphite of 

 lime. The proportions of the ingredients and the method of 

 combining them vary slightly in different sections. The following 

 is the ordinary formula : Unslaked lime, 40 pounds ; sulphur, 20 

 pounds ; salt, 15 pounds. One-fourth of the lime is first slaked 

 and boiled with sulphur in 20 gallons of water for two or three 

 hours ; the remainder of the lime is slaked and, together with the 

 salt, is added to the hot mixture, and the whole boiled for half an 

 hour or an hour longer. Water is then added to make 60 gallons 

 of wash. This wash is applied practically every year, or as often 

 as the San Jose scale manifests itself in any numbers.' 



Carbolic Acid. — Crude carbolic, phenol, Jeyes' fluid, and similar 

 compounds, all have insecticidal properties. Carbolic acid itself 

 has been found inefficient except when applied in such strength as 

 to seriously damage the plants, I find that phenol and Jeyes' 

 fluid (which appears to be much the same thing) are effective 

 against Orthezia, ' mealy bugs,' and most species of Lecaniuui. A 

 mixture containing i part of Jeyes' fluid to 20 of water, applied to 

 a Thunbergia bush attacked by Orthezia, was fatal to more than 

 90 per cent, of the insects, but resulted in the death of the terminal 

 buds of the plant. It had no bad effect upon the more mature 

 leaves and shoots. The application did not, however, prevent the 

 subsequent hatching of the eggs in the ovisacs of the dead insects. 

 Weaker solutions were proportionately less effective. 



In a ' Report on the Green Scale Bug, Lecaiman viridc,' pub- 

 lished in 1886, I have mentioned that phenol applied to the 

 ground around the roots of the coffee tree appeared to cause the 

 disappearance of the scale. But subsequent experiments have not 

 corroborated this result, and I must suppose that the apparent 

 benefit in the earlier experiment was due to some other cause. 

 Single experiments are practically useless. They are liable to be 

 vitiated by adventitious circumstances. Until similar results have 

 been obtained from repeated experiments, no confidence can be 

 placed in any treatment. 



Tobacco Water. — ' Steep 5 lbs. of refuse tobacco (stems, &c,) 

 in 3 gallons of water for three hours. Strain the decoction and add 

 sufficient water to make 7 gallons.' This mixture will kill soft- 



