303 



poison. With most of them there is the difficulty that they clog or do 

 not sift regularly, especially when they are atfected with wetness, which 

 will generally occur, for the best time to apply the dry poison is 

 when the foliage is damj) enough to make it adhere. Also the adhesive 

 diluents, as flour, &c., which it is advisable to add to the poison increase 

 the clogging much under the influence of moisture. On the other hand, 

 when there is dryness there generally exists a little wind which prevents 

 the fine powder from gravitating regularly from the sieve to the plants. 

 The powder is better thrown by some device that will give it consider- 

 able imi>ctus, and on this account the centrifugal force from whirling- 

 brushes or the blast from a bellows or pumj) or rotary fan-blower is 

 preferable. Such impetus will make it penetrate more firmly into the 

 rough surfaces of the foliage or into the moisture upon the plants, and^ 

 to some extent, resist moderate breezes. The operation of the latter 

 machines is also less affected by moisture. Although sifters may not 

 be recommended generally, it is necessary to notice briefly what has 

 been done toward the application of sieves to the purposes of poisoning. 



With sifters there is also probably more danger of the laborer getting 

 poisoned than with machines of any other class. Where a blast or squirt- 

 ing i^ower is used the poison can be directed away from the operator 

 with some force, or be discharged from a pipe extending to a safe dis- 

 tance from him, but with sifters the fine powder follows the caprices of 

 the wind, and even with a gentle breeze there constantly exists on the 

 leeward side of a x^erson a varying weak whirlwind, but one which 

 is strong enough to lift some of the poison to his face and cause it to be 

 inhaled. It was probably' on account of this difficulty that Mr. J. W. 

 Young patented, in combination with his machine described below, a 

 screen to come between the sifter and the person using it. 



Eecipkocating- SIEVE MACHINES. — With these the sieve itself is 

 operated by a back-and-forth movement. 



Concerning the method of poisoning with the simplest hand-sifters^ 

 Mr. William Trelease has reported as follows in the Department Eeport 

 on Cotton Insects (p. 221) : 



'' My dry poisons were applied by a sieve made of a 2-quart tin bucket, 

 the bottom of which was replaced by perforated tin, and which was pro- 

 vided with a socket at the side for the insertion of a wooden handle 

 about 3 feet long. 



" My experiments with dry poisons were not extensive enough for me 

 to determine accurately the amount of labor required to poison an acre; 

 but Mr. Lide, the manager of George O. Baker's plantation at Selma, 

 Ala., tells me that a hand can poison from 1 to 2 acres of cotton per 

 day. He tells me, further, that one barrel of Eoyall's mixture goes over 

 about 3 acres." 



Thus it is seen that the work with such a tool is very slow, and can 

 only be admissible for very small patches or in an emergency where bet- 

 ter means are not obtainable. 



