FUMIGATION OF CITRUS TREES. 49 



much of the liquid from the vessel. In one instance about 1 pound 

 of cyanid was dissolved in water hi a 2-gallon generator. Acid was 

 then added, producing a disturbance so violent as to throw some of 

 the liquid almost to the top of a 2-story barn. 



The cyanid should be in pieces anywhere from the size of an English 

 walnut to that of a good-sized lemon. The smaller pieces should be 

 used in the small dosages. Powdered cyanid should be avoided in so 

 far as possible. Where purchased in large boxes there is always a 

 considerable quantity of fine material at the bottom. Entire dosages 

 for a tree should never be composed entirely of this character of 

 cyanid or a violent reaction will take place, blowing much of the 

 fine particles out of the generator and endangering the tent as well 

 as the operator. This fine cyanid is most economically and satis- 

 factorily disposed of by using it in small quantities along with lumps. 



The generation of gas has practically ceased at the expiration of 

 from three to five minutes. 



Many writers on fumigation recommend the use of paper bags for 

 holding each dosage when placed in the generating pot. These bags 

 are used largely to retard the reaction so that the operator may 

 retreat to some distance before the generation commences or else 

 to prevent slopping. The writer's own experience, as well as some 

 principles previously mentioned in this chemical discussion, would 

 lead to advising against the use of paper bags. The retardation of 

 generation is so marked in the case of small dosages in heavy paper 

 bags that the amount of gas resulting must be considerably less 

 than if the cyanid had been introduced in a free state. 1 By the exer- 

 cising of a slight amount of care in introducing cyanid in the free 

 state into a generating vessel there is no danger of the operator 

 being affected by the gas or of the acid being slopped out. Neither 

 will the generating pots boil over if the amounts scheduled on page 

 24 are used. Fine or powdered cyanid should never be used in 

 houses. In household work sheets of heavy paper should be placed 

 underneath the generators. 



EFFECT OF THE PRESENCE OF SODIUM CHLORID ON THE AMOUNT OF 



GAS GIVEN OFF. 



Practically all commercial cyanid contains more or less common 

 salt, technically known as sodium chiorid. The action of this salt 

 in connection with fumigation demands consideration. It has been 

 found, when sodium chiorid is present in the reaction of sulphuric 

 acid on a cyanid in the production of hydrocyanic-acid gas, that 

 this chiorid salt produces a secondary reaction which liberates an 

 arid called hydrochloric acid, and that this liberated hydrochloric acid 



1 If paper sacks are employed, they should be of thin paper, or slit to allow the free action of the acid on 

 the evanid.— 0. L. M. 



