32 2 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908. 



solubility in water of the arsenious oxide, which frequently causes 

 damage to foliage. For this reason entomologists have sought a 

 different poison, which would be effective against insects, harm- 

 less to plants, and economical for the farmer to use. Lead 

 arsenate seems to meet these requirements, and possesses a still 

 further advantage over Paris green in that its mechanical condi- 

 tion keeps it longer in suspension in the spraying mixture. 

 There are a number of brands of this material on the market, 

 varying greatly in appearance and consistency, and it was con- 

 sidered advisable to make a somewhat extended chemical 

 examination of them to determine their relative value. As the 

 various brands of Paris green on sale in this State had never been 

 analysed at this station, they also have been included in this 

 examination. 



METHODS OF ANALYSIS. 



In the £inalysis of lead arsenate the method proposed by Hay- 

 wood* has been followed in all particulars, and has proved very 

 satisfactory. With Paris green the same methods as used by the 

 writerf in a similar examination at the New Jersey Station have 

 been followed. In addition, however, a test of the water-solu- 

 bility of the arsenious oxide was made by the official A. O. A. C. 

 method, J treating the green with distilled water for- ten days. 



LEAD ARSENATE. 



Ten of the eleven samples analysed were taken from the 

 museum stock of Dr. Britton, the State entomolc^st, but were 

 recently acquired and were believed to be representative; the 

 dupUcate sample of Swift's arsenate was bought in the open 

 market. The samples were received in containers of various sizes 

 and material, from a one-pound glass jar to a fourteen pound 

 wooden bucket. The material itself showed striking differences 

 in consistency. Disparene settled out completely, leaving a 

 supernatant liquid filling from one-fourth to one-third of the 

 vessel ; the Target brand and Swift's also showed some separated 

 liquid, while the others were more of the consistency of putty 

 and quite homogeneous. 



The samples analysed were as follows: 



* U. S. Dept. of Agr., Bur. of Chem., Bull. 105, 165. 



t New Jersey Expt. Station, Bull. 195. 



tU. S. Dept. of .'S.gr., Bur. of Chem., Circ. 10, 3. 



