21 



The cyanide used is between 98 and 100 per cent, pure, and the 

 sulphuric acid is 94 per cent. pure. This grade of acid is the 

 ordinary, commercial article; the specific gravity is 1.84. Only 

 these grades of chemicals should be used with this table. The 

 cyanide is weighed in avoirdupois ounces, and the water and acid 

 measured in fluid ounces. 



The table is based on the assumption that proportionate amounts 

 are required for trees of different sizes, and that the spaco encom- 

 passed by the cloth is rounded above. One ounce of cyanide is 

 taken as sufficient for 300 cubic feet. The approximate number of 

 cubic feet enclosed is given in the table to show the relation of one 

 tree to another. The quantity of cyanide allowed for the smallest 

 size of tree given in the table is slightly out of proportion to that 

 allowed for larger trees; the reason for this is the difficulty of 

 working with a quantity so small as the proportionate amount 

 without losing as much in handling as might vitiate the lesults. 

 The table has not yet been used for trees over twenty feet in height. 



For several months a table based on the one published by the 

 California State Board of Horticulture (1893-94 Report, p. 106) and 

 by the Los Angeles Horticultural Commission was followed. The 

 quantities recommended for use in this table are not proportionate 

 to the spaces enclosed. This fact was recognised, but deeming that 

 the table had been widely and successfully made use of in California, 

 it was thought perfectly safe to use one based upon it. The results 

 were satisfactory when trees from 8 to 14 feet were treated but the 

 dose for smaller trees proved far too large, and for larger trees, 

 evidently too small. 



An explanation of the table was asked of Mr. Alex. Craw, the 

 -Entomologist of the California State Board of Horticulture, in a letter- 

 addressed to him in September, 1896, but no reply was condescended. 

 Long puzzling over the table, however, has led to the conviction 

 that the quantities are intended to be proportionate. It would 

 appear that the proper amount for a tree of medium size, presumably 

 one 12 feet in height, had been ascertained in practice, and that the 



