HOME-MADE SOLUBLE OILS. 837 



needed. A hexagonal form was made of wood one-quarter 

 inch thick, with a tack through the center to prevent the form 

 from slipping and to mark the center of each disk. The form 

 being placed on the paper, a sharp knife was used to cut around 

 it. A row of disks were cut from the full width of the paper 

 and then stacked together, when the cut a-b (Figure 19) was 

 made with the knife; c, d and e were made with a sharp chisel, 

 which in this case was 1% inches wide. After the first row 

 has been cut, the paper will have an edge with regular points, 

 which should be used to form two sides of the next row of disks. 



Figure 20 shows the form placed to start another row of disks, 

 and the dotted lines show that but three cuts are required to 

 make each succeeding disk. 



While this method would not be practicable for a large com- 

 mercial grower, it will answer where but a few thousand disks 

 are needed. They can be made at odd times during the winter and 

 early spring. If made much in advance of the time when needed, 

 however, they should be tightly wrapped and kept in a rather 

 moist place so that the tar will not dry out and the disks become 

 hard. 



EXPERIENCES WITH HOME-MADE SOLUBLE OILS 



AND SOME OTHER SPRAY MIXTURES. 



By W. E. Britton and B. H. Walden. 



Probably the most important development in spraying for San 

 Jose scale in 1907 was the working out of formulas for the pre- 

 paration of home-made soluble or miscible oils, so that the 

 orchardist can make them on his own place. 



Professor Charles L. Penny, now of the Pennsylvania Station, 

 but formerly chemist of the Delaware Station, has done much 

 investigating along this line, and the results of his efforts were 

 published in Bulletins No. 75 (June 18, 1906) and No. 79 (August 

 I, 1907) of the Delaware Station. 



Mr. C. D. Jarvis, horticulturist of the Storrs (Conn.) Station, 

 had also been working on soluble oils, and in Bulletin 49 (Novem- 

 ber, 1907) recommends a formula which he found best for 

 general purposes. 



The bulletins by Professor Penny explain the principles of 

 making these mixtures and the role played by each of the 



