156 The Spraying of Plants. 



vised since the arsenicals and a certain amount of the emulsion 

 appear to separate in the form of clots that adhere with surpris- 

 ing firmness to the sides of the vessel in which the preparation 

 is made, and render its use practically impossible. 



KEROSENE EMULSION AND BALSAM OF FIR. The addi- 

 tion of two ounces of fir balsam to the Hubbard-Riley emul- 

 sion is said to increase its efficiency and also its adhesive 

 properties. 



One-half pint of turpentine may be used for the same pur- 

 pose. 



KEROSENE EMULSION AND BORDEAUX MIXTURE. A mix- 

 ture between these two preparations may be obtained without 

 much difficulty, but the fungicide should be made with as little 

 lime as possible. For this purpose, employ the ferrocyanide 

 of potassium test. Applications of the mixture can scarcely be 

 advised, however, since both fungicide and insecticide appear to 

 lose a certain degree of their efficiency, since such even distribu- 

 tion on the foliage cannot be obtained as when the two are 

 applied separately. 



KEROSENE-PYRETHRUM EMULSION. This emulsion is made 

 in the same manner as the preceding ones, but pure kerosene 

 is not used. A decoction of pyrethrum is made by filtering 

 1 gallon of the oil through *2\ pounds of the powder, and this 

 decoction is then treated like pure kerosene. It is little known. 



LEAD ARSENATE. See ARSENATE OF LEAD. 



LIME. Quicklime is the most valuable form of the metal 

 calcium to be used in spraying, although the compound does 

 not remain in this form. Quicklime is the oxide of calcium, 

 CaO. When water is added to it, there is formed the hydrate 

 of lime, or calcium hydroxide, Ca(OH) 2 , or water-slaked lime, 

 as it is more commonly called. When exposed to air, quicklime 

 sooner or later combines with carbonic acid gas and is thus 

 converted into the carbonate of lime, or air-slaked lime, CaCO.,; 

 this is the same, chemically, as limestone, or chalk. 



The milk of lime is formed by slaking quicklime in water. 

 It possesses little value when used alone, either for combating 

 insects or fungi, but is extensively used to avert the caustic 

 action of other preparations. If sprayed upon plants, it may be 

 found desirable to strain out the coarser particles to prevent 

 clogging the machinery. Air-slaked lime has been used in 



