298 BOARD OF AGRICULTURE. [Pub. Doc. 



glass jars filled with shot, and by their use the ingredients 

 may be accurately weighed, when they should be placed in 

 stout paper bags, each package of arsenate of soda being tied 

 inside of the corresponding package of the lead salt. In this 

 way compact, convenient packages of the insecticide may be 

 rapidly prepared. When desired for use, the arsenate of 

 soda should be dissolved in a wooden tub, the acetate of lead 

 being dissolved in a separate tub. The two solutions are 

 then poured into the spraying tank, and the arsenate of lead 

 is ready for use. The ingredients should never be dissolved 

 in metallic vessels. 



It is a good plan to first test the formula used by mixing 

 a trial lot of arsenate of lead and allowing it to settle in the 

 mixing tub. A few drops of chromate of potash solution 

 added to the clear liquid which separates above the arsenate 

 of lead should cause the formation of a yellow precipitate. 

 This indicates that an excess of soluble lead is present, and 

 consequently that all the soluble arsenic has been neutralized. 

 A firm of manufacturing chemists, located at Boston, has 

 this year placed upon the market an excellent brand of ar- 

 senate of lead in paste form, thus saving the delay incident 

 to the preparation of the insecticide. 



Kerosene Emulsion. — This insecticide is prepared by dis- 

 solving one-fourth pound hard soap in two quarts hot water, 

 and adding to the soapsuds thus formed one gallon kerosene 

 oil. The whole is stirred or churned until cool, when a 

 white, creamy emulsion is formed. This emulsion should be 

 diluted with nine parts of water. Kerosene emulsion kills 

 by contact, and is a valuable agent for killing the larva3 and 

 pupai of the elm-leaf beetle clustered in the bark or in masses 

 on the ground under the infested trees. 



Useless Measures. 



In cases of extensive injury by the elm-leaf beetle, indi- 

 viduals often spend in useless channels a large amount of 

 energy which intelligently applied would be productive of 

 good results. Among the more common mistakes arc : — 



Tar Bands. — These serve to prevent damage by the 

 canker worm by intercepting the wingless female moth on 

 her way up the tree to deposit eggs. The female elm-leaf 



