204 



■weight of the dry cyanide. At this rate, by the old process, a tree 14 

 feet high by 12 feet in diameter required 21J ounces by weight of the 

 dry cyanide, whereas by the new process it will require only 7^ ounces. 

 At the present prices of the cyanide and acid, the cost of the materials 

 necessary to treat an orange tree of the size given above, by this new 

 method will amount to about 26 cents, as compared with 76 cents, the 

 price when the old process is used. 



Not only is the new process much cheaper than the old, but it is also 

 attended with much less labor. By using the cyanide dry we are saved 

 the trouble of first dissolving it; the dry cyanide is also easier to trans- 

 port and safer to handle than the solution is, and if the vessel contain- 

 ing it should be accidentally overturned on the ground, the dry cya- 

 nide will not be lost, as it certainly would if dissolved. By thus using 

 the cyanide dry it is not necessary to first pass the gas through sul- 

 phuric acid in order to render it harmless to the treesy thereby saving 

 a great deal of labor, and admitting of the use of a much simpler and 

 less expensive generator. By placing the latter beneath the tent there 

 is less liability of the gas escaping while being generated and intro- 

 duced into the tent from without, thereby also insuring the operator 

 greater immunity from inhaling the gas. I also found that by thus 

 placing the generator under the tent the blower heretofore used for 

 distributing the gas inside of the tent could be done away with, thereby 

 still further reducing the original cost of a fumigating outfit, besides 

 doing away with the labor necessary in operating the blower. The 

 time during which it is necessary to confine tlie tree in the gas has also 

 been reduced one-half as compared with that heretofore allowed for 

 destroying the Fluted Scale {Icerya purchasi Maskell), thereby rendering 

 it possible to treat twice the number of trees in a given time that could 

 be treated in the same time by the old process. I found by experiment 

 that about five minutes were consumed each time in generating the gas. 



The treatment with hydrocyanic acid gas is the only method known 

 to me whereby the scale-insects located upon the fruit can be destroyed 

 by a single operation. My own experience, and that of every other per- 

 son with whom I have conversed upon this subject and who has had 

 any considerable experience in the matter, indicates that no liquid prep- 

 aration at present known will by a single application prove fatal to 

 more than 90 per cent, of the number of red scales located upon the 

 fruit, and when it is remembered that the supervisors of many counties 

 in this State have passed laws making it a misdemeanor to sell or ex-' 

 pose for sale fruit infested with scale-insects, the value of the gas 

 treatment to our fruit-growers is made apparent. 



The following is an account of the experiments I made with hydro- 

 cyanic acid gas as referred to above. The trees operated on were all of 

 them lemon trees containing fruit, and were in a comparatively healthy 

 condition, although very thickly infested with the Red Scale. Before 

 making these tests, I had the experimental tent painted black, and am 



