19 



On motion of ^Ir. Howard, tlie president and secretary were consti- 

 tuted a programme (H)mmittee, 

 Mr. Marlatt read the following paper: 



NOTES ON INSECTICIDES. 



By C. L. Maklatt, Washington, D. C. 

 KEROSENE AND WATER SPRAY. 



At the previous meeting of the association J called attention to the 

 kerosene and water pump designed by Prof. E. S. Goff, of the Wis- 

 consin Experiment Station, and put on the market by the Deniing 

 Company. A thorough testing of this apparatus indicated that the 

 percentage of kerosene in the water varied with a number of conditions, 

 such as the comi)arative fullness of the two tanks, the imperviousness 

 of the two reservoirs to air, and, as afterwards explained by Mr. Goff, 

 the accumulation of oil in the air chamber of the pumj) (hiring the 

 action of pumping, and its escape therefrom as soon as piessure is 

 released. As a result, it was impossible to know what percentage of 

 oil was coming from the nozzle at any time, and it was concluded that 

 the apparatus w^as entirely unsuited for careful work, particularly if 

 placed in the hands of comparatively unintelligent laborers. The 

 inventor of this apparatus has since suggested a new combination 

 spray pump to overcome the objections pointed out. This apparatus 

 was described in Garden and Forest, April 10, 1895, and was devised 

 to insure a uniform level for oil and water, and by a different arrange- 

 ment of the discharge pipes to avoid the accumulation of oil in the air 

 chamber of the puni]). I have no doubt that this apparatus of Mr. 

 Goff' corrects some at least of the defects in the first apparatus. Xo 

 opportunity to experiment with it has offered, however, as it is not 

 being manufactured. 



Prof. H. E. Weed, of the Mississippi Experiment Station, has, how- 

 ever, described a new modification of the original knapsack kerosene 

 sprayer (Miss. Agric. Exper. Sta., Bull. .')2), which he claims to be more 

 satisfactory. This apparatus is being manufactured by the Deming 

 Company and supplants the one originally made by them. It is the 

 apparatus as originally made, with the addition of a check valve to 

 the oil chamber and a graduated arrangement for the oil stopcock, 

 by means of which the oil is indicated on the gauge in percentages 

 ranging from o.^ to 50. A sample of this apparatus was secured, and, 

 with the assistance of Mr. II. S. Clifton of the division, a scries of 

 experiments was made with it, both in si)raying the licpiid into gradu- 

 ated Jars, to determine the actual percentage of oil, and in testing its 

 action on foliage. All the old objections to this apparatus were devel- 

 oi)ed in the experiments. The Cnllncss of tlie oil and water tanks 

 exerted considerable influence on tiie ])erccntagc of oil, as in the ft>rmor 

 instance, the best results being obtained when the tanks were botli half 

 or more than half tilled. After having been reduced by spraynig much 



