SOME FLY POISONS FOR OUTDOOR AND HOSPITAL USE. 331 



morning all were dead ; a 1% solution killed 18 out of 58 on the morning of the 

 second day. As cadmium salts were considered too poisonous for practical use, 

 further trials were abandoned. 



Paris green. This insoluble arsenic salt was thoroughly mixed with food 

 mixture at a 2% strength and was fed to flies ; at 10 a.m. next morning, 6 flies out 

 of 16 were dead and by 5 p.m. 12 out of 16. As this substance is excessively 

 poisonous no further trials were made. 



Cacodylic acid (1 : 1,000) accounted for 38 out of 53 flies by the morning of the 

 second day. As it is excessively poisonous, no further experiments were made. 



Toluol parachlorsulphonate was very insoluble ; to get it into solution alcohol had 

 to be added. An approximately 2% strength killed no flies the first day and about 

 50% by the morning of the second day. 



Phenyl hydrazine hydrochloride (2%) killed 3 out of 35 by the evening of the 

 first day, and 23 out of 35 by 10 a.m. next morning. 



Pyrogallic acid (2%) killed no flies on the first day ; on the morning of the 

 second day 16 out of 41, and by the morning of the third day 38 out of 41. 



Naphfhyhmine (2%). This substance is not miscible in water, and had to be 

 dissolved in ammonium oleate, sugar solution being added. By 10 a.m. next 

 morning 34 flies were dead out of 49. 



Quassine. An approximately '4% solution was used, but this substance is rather 

 insoluble. The experiment was started at 4 p.m. and by 6 p.m. 8 out of 68 flies 

 were dead, and at 10 a.m. next morning 48 in all were dead. 



Iron perchloride (5%) accounted for 1 out of 32 at 5 p.m. of the first day, and 

 next morning 27 flies were dead. At 2% strength, 1 fly out of 26 was killed by 5 

 p.m. of the first day, and next morning at 10 a.m. 22 were dead. At a 1% strength, 

 at 5 p.m. 8 were dead and many alive ; next morning only 9 dead and many alive. 



Iron alum (2%) killed 1 out of 40 by the evening of the first day (experiment 

 started 10.25 a.m.) ; by 10 a.m. next morning about 50% were accounted for. 



Iron fluoride was only fairly soluble in sugar solution. An approximately 2% 

 strength killed 5 out of 30 by 5 p.m. (experiment started 12.50 p.m.) ; next 

 morning 21 in all were dead. 



Allyl alcohol (2%) accounted for 30 dead out of 76 by 6 p.m. (experiment started 

 at 4 p.m.) ; next morning at 10 a.m. 56 were dead. This substance is too volatile 

 to be of any practical use. 



List of compounds tested. 



The following list gives all the compounds tested, with the classes in which they 

 are placed indicated by the Roman figures in brackets. Where not otherwise 

 indicated, they were used at 2% in sugar solution ; when they failed, the}' were 

 placed in class III. 

 Inorganic. 

 Sodium hydroxide 1% (III). 



,, carbonate 5% (III), 

 sulphate 5% (III). 



„ acid sulphate 5% (III). 



