530 



Journal of Agricultural Research voi. xiii, no. u 



Table II.— Viscosity of various oils 



Material. 



Water (distilled) 



Kerosene (b. p. i4o°-i87°) 

 Kerosene, unfractionated. . 



Kerosene (234°-28o°) 



Turpentine oil 



Lubricating oil i 



Red oil 



Fish oil 



Lubricating oil 2 



Whale oil 



Boiled linseed oil 



Raw linseed oil 



Cottonseed oil 



Lubricating oil 3 



Lard oil 



Olive oil 



Lubricating oil 4 



Knochen oil 



Lubricating oil 5 



Lubricating oil 6 



Lubricating oil 7 



Castor oil 



Lubricating oil 8 



Lubricating oil 9 



Lubricating oil 10 



Lubricating oil 11 



Lubricating oil 12 



Lubricating oil 13 



Lubricating oil 14 



Lubricating oil 15 



Time. 



Seconds. 



3-3 



3-6 



4. 6 



5-2 



5-4 



46. 5 



54- o 



66.0 



68.0 



73- o 

 77.0 

 81. o 

 88.0 

 99.0 



103. o 



104. o 



115-0 

 128. o 



177.0 

 194.0 



495- o 

 I, 205. o 

 1,472.0 



1, 740. o 



2, 340. O 

 2, 610. O 



2, 707. O 



3. 568- o 

 5, 462. o 



viscosity, in 

 terms of water. 



I. CO 

 I. ID 

 I. 40 



1-57 



I. 60 



14- 10 



16.32 



20. 00 



20. 60 

 22. 12 



23-33 

 24- 54 

 26. 66 

 30. 00 



31-51 

 31.82 



34.85 

 35-88 

 53-66 

 58.78 

 150. 00 



365- 15 

 446. 06 



530. 30 

 709. 09 

 790. 90 

 820. 90 

 I, 081. 30 



1,655. 15 

 2,374.27 



Spreading ability. 



Rapid spreader. 



Do. 



Do. 



Do. 

 Slow spreader. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 

 Very slow spreader. 



Do. 



Do. 



Do. 



Do. 



Do. 

 Too slow for effect- 

 ive work. 



Do. 



Do. 



PENETRATION OF THE INSECTICIDE INTO THE TISSUES 



Shafer {16) has shown that contact insecticides, such as kerosene and 

 others of a similar nature, are able to penetrate the tracheae of an insect, 

 but he considers that it is the vapor from these substances, which is 

 responsible for the killing, inasmuch as the rate at which the liquid itself 

 will pass through the chitin is too slow to account for the death of the 

 insect. He dissolved Sudan III in kerosene to show the passage of the 

 oil through the walls of the tracheae. At the time of the death of the 

 insect he could find no evidence of a red stain in the tissues, and it was 

 not until the insect had been dead for a long time and the fat bodies had 

 been partially dissolved that he could detect traces of the stain in the 

 tissues. Sudan III, however, is a colloid, and would not be able to pass 

 but very slowly through a semipermeable membrane such as chitin. 

 Thus, the inability of the stain to pass through the chitin did not neces- 

 sarily imply that the kerosene had not been able to penetrate into the 

 tissues. If the experiment is repeated with picric acid instead of Sudan 

 III, it is found that the tissues are very quickly stained yellov/. There 

 are, however, a number of objections to the use of a stain to indicate the 



