40 Bulletin 832 



about the same, but if there is a difference "JMechling's Scale-Oil" 

 is lighter than ' ' Scalecide. ' ' 



During ^March and April, 1917, a number of experiments were 

 conducted with the above-mentioned miscible oils on the eggs of 

 A. avencB in the greenhouse and on the eggs of A. avence, A. potni 

 and A. sorhi out-of-doors at the laboratory. Also one experiment 

 was conducted with "Scalecide" against the eggs of A. avence {A. 

 sorhi, 15 per cent) at John H. Barclay's orchard. The results of 

 the more important experiments with "JMechling's Scale-Oil and 

 "Scalecide" are shown in table 4. Experiments G-27, 0-29 and 

 0-31 where "Mechling's Scale-Oil" was used at the rate of 1-19 

 showed a 6.3, 8.1 and 8.5 per cent hatch, respectively, while "Scale- 

 cide" 1-15, in experiments 0-34. 0-36, 0-38 and 0-40, showed a 23.0, 

 34.6, 22.8, and 31.7 per cent hatch, respectively. In other words, 

 three to four times as many eggs hatched when treated with "Scale- 

 side" as with "Mechlings' Scale-Oil." 



A comparison of the results obtained in the use of the two 

 miscible oils shows that "Scalecide" 1-15 is not as effective in 

 killing eggs as "JMechling's Scale-Oil" 1-19, and that neither may 

 be depended upon to kill all the eggs or act as a satisfactory control 

 when applied at the strengths recommended for dormant spraj^. 

 Since both sprays are manufactured from low gravity oils it was im- 

 possible to explain the decided difference in the percentage of kill 

 on the basis of the specific gravity of the oil, but it was apparent 

 that some chemical might be present in one which did not occur in 

 the other. In conjunction with the experiments with miscible oils, 

 crude carbolic acid was used alone and in combination with the 

 miscible oils, and it was noted that the eggs of all three species 

 were Tiighly susceptible to cresols and phenol ; consequently, it was 

 thought that the presence of these chemicals might explain the 

 difference in the effectiveness of the two oils. In the first place, 

 it was noted that "Mechling's Scale-Oil" had a distinct phenol 

 odor, while this was not true of "Scalecide." The two oils were 

 subjected to two qualitative tests (Landolt's and Lieberman's) 

 (14, 22) for cresols and phenol. "JMechling's Scale-Oil" gave a 

 decided test for cresols and phenol while "Scalecide" gave no in- 

 dication. A short time after this the two companies kindly sub- 

 mitted an analysis of their respective products. And the manufac- 

 tures of "Scalecide" definitely stated that their product contained 

 no carbolic acid .while IMechling Brothers' J\rannfacturing Company 

 gave a guaranteed analysis of 4.5 to 6.^) j>er cent of phenol deriva- 

 tives for "Mechling's Scale-Oil". 



The presence of the phenol derivatives in "JMechling's Scale- 

 Oil" and their absence in "Scalecide" probably accounts in large 

 measure for the decided difference in th.e effectiveness of the two 

 oils. In all the experiments G-28. 0-30. G-35. 0-37 and 0-39 (table 



