31 



All the sulphur and half of the lime are placed iu a kettle and 33 

 gallons of water added, after which the contents of the kettle are boiled 

 briskly for about 1 hour ; the solution will then be of a very dark brown 

 color and having a reddish tint. All of the salt is added to the remain- 

 ing 21 pounds of lime and the latter slaked, after which this slaked 

 lime and salt are added to the above described sulphur and lime solu- 

 tion and the whole then diluted with a sufficient quantity of water to 

 make 100 gallons ; this is then strained, after which it is ready to be 

 sprayed upon the trees. 



This does not form a perfectly liquid solution but contains a consid- 

 erable quantity of undissolved sulphur and lime, which soon settles to 

 the bottom unless the solution is stirred almost constantly while being 

 sprayed on the trees. It is therefore somewhat of the nature of a thin 

 whitewash, and the trees sprayed with it have the appearance of hav- 

 ing been whitewashed. On the 26th of November, at 12:45 p. in., sun 

 shining, light breeze, I sprayed a pear tree with a wash made according 

 to the above directions, the tree being very thickly infested with the 

 San Jose scale. January 15 I found 14 living San Jose scales on tbis 

 tree, and on the 23d of April 1 found several more ; on the 11th of 

 June I found on this tree a Black scale (Lecanium olece Bernard) con- 

 taining healthy eggs. 



I also tested this wash in the following proportions : 



Sulphur , pounds.. 50 



Lime , do 63 



Salt do.... 37 



Water enough to make gallons . . 100 



This was applied to a pear tree at 1 p. m., November 26, sun shining, 

 light breeze. On January 15 I found 6 living San Jose scales on this 

 tree, and on the 23d I found several more. 



At the time of making these tests there were several green leaves on 

 each of these trees, but all of these were killed by the washes. The 

 trees otherwise were not apparently injured, and in the following spriug 

 started into a vigorous growth which was- continued throughout the 

 summer. These trees were not over 10 feet tall, and were very thor- 

 oughly sprayed, so it seems quite certain that every scale insect located 

 upon them must have been covered with the wash. 



The philosophy of this wash is not at present clearly understood. ±t 

 seems very probable however that the product of the lime and sulphur 

 (bisulphide of lime, CaS 2 ) furnishes the insecticidal property, and the 

 presence of the salt and slaked lime simply imparts permanenc3 r to the 

 wash. I made quite a series of experiments with the above-named in- 

 gredients, with a view of ascertaining which of the ingredients were 

 really insecticides, but these experiments have thus far resulted nega- 

 tively. The following is a brief account of these experiments : 



Salt.— Experiment 229 : Table salt, 19 pounds ; water, 100 gallons. 

 I simply dissolved the salt in cold water and then sprayed the solution 



