MONTANA EXPERIMENT STATION. 263 



The water is placed over a stove to heat and the soap shaved 

 into it. When the soap is dissolved and the water has reachedd the 

 TDoiling point the solution is poured into the kerosene and vigouous- 

 ly churned for four or five minutes with a force pump the nozzle of 

 which is directed back into the vessel. The mixture takes on a 

 milky appearance and on cooling- becomes jelly-like. This is the 

 stock emulsion and if properly prepared will keep for a considerable 

 length of time, but should be diluted when used. 



Whale-oil Soap. 



Whale-oil soap, more c<)rrectly known as fish-oil soap, is of 

 great value as an insecticide against certain classes of insects par- 

 ticularly scale insects. Some species of plant lice which fail to suc- 

 cumb to an application of very strong kerosene emulsion are readi- 

 ly killed with a solution of whale-oil soap. An example is the louse 

 so commonly attacking spruce trees in Montana causing cone-like 

 galls on the twigs. 



Ordinary foliage will not safely stand a stronger solution than 

 one pound in four gallons of water. Most plant lice are readily kill- 

 ed by I pound in 6 gallons of water. If a good whale-oil soap can- 

 not be obtained a substitute may be made by the following formula: 



Concentrated lie 3^ pounds. 



Water 8 gallons. 



Fish-oil I gallon. 



Dissolve the lie in boiling water and add the oil to the solution 

 still boiling. Continue to boil for two and a half hours and then 

 allow it to cool. The fish-oil can be obtained in eastern markets and 

 beyond doubt it would be cheaper for the fruit-grower to make his 

 own soap provided he intends to use a considerable quantity. 



Lime-Sulphur-Salt Solution. 



This insecticide is used chiefly as a means of destroying the 

 San Jose scale, but is of great value also as a remedy for many other 

 pests. Though various formulae have been given for the preparation 

 of this wash, the active caustic principle is the same in all. The 

 caustic ingredient is produced by the union if the sulphur and lime. 

 In part two of Bulletin 56 of the Washington Experiment .^titio:. by 

 •Prof. C. V. Piper and R. W. Thatcher it is shown by accurate chem- 

 ical processes that, practically speaking, one part of lime causes two 

 parts of sulphur to go into solution and that the presence of salt in 

 the solution does not influence the action of the sulphur and lime 

 upon each other, it follows then, that if a greater proportion of lime 

 is used, the excess goes onto the tree merely in the form of a white- 

 wash, and if the salt has any value it is purely a mechanical one, for 

 salt in such a small proportion is valueless as an insecticide. We 



