INSECTICIDE STUDIES. 



I.KAD AKSK.VATK AM) I'INK AKSKNOII). 



The analyses of samples of Lead -Arsenate and Pink Arsenoid, or 



Lead Arsenite. arc given in- the following table: 



TAUI.K VIII. i'nnii,nx'itinit of /,,<></ Arsenate u<l I 'ml: . 



i All tin- k-iid oxid calculated to JM...,. AsO 4 ) 2 leaves an excess of 0.05 per cent arsenic oxid. probably 

 combined as sodium arsenate. 



i> All the lead oxid calculated to Pb :{ (AsO 4 ) 2 leaver an excess of 1.38 percent arsenic oxid, ]>rol)al)ly 

 eomV)ined as sodium arsenate. 



-This analysis \vas made in accordance with the Texas law retfulatintf the sale of Paris Green and 

 other insecticides and is good only until May 1, 1903. In addition to constituents named, 2.7 per cen 

 organic matter was found. 



'/The chemist reported arsenic in the following ways on these :> samples: (1) White arsenic. (2) 

 total arsenic, (3) white arsenic, (4) white arsenic, (5) arsenious oxid. These terms are usually 

 applied to arsenic when in the "ous" condition and mean s:> much As,O :< . If these compounds are 

 ar-enates, as claimed, the arsenic should be reported as As.,0,. In several of the above analyses, 

 however, it" the figures as given were calculated to As.,0,-,, the sum total of the constituents would be 

 markedly above 100 per cent. 



J Analysis made according to Texas law, but good only until May 1, 1902. 



/Includes organic; matter also. 



>j In addition to constituents named 6.85 per cent of organic matter, lead sulphate, etc., was found 



It is at once evident that the variation in the composition of samples 

 of Lead Arsenate is considerable, depending* to a large extent on the 

 variation in the moisture content and somewhat on the variation in 

 method of manufacture. These differences in composition should be 

 borne in mind in using such compounds for spraying purposes, since 

 some of them would not have the same insect-killing powers as others 

 at the same dilution. Pink Arsenoid, although somewhat variable in 

 composition, is much more constant than is Lead Arsenatc. 



\\. ITKPI.K 1'MlSoN, \M> I\SK( TICIDK. 

 Tvi'.I.K IX. t'nmiKixilinii nl' XX, /'tirii/f I'nifnin. <tn<t 



"The I'urple poison, sample No :.o|, n\- eontaiiiM'olonni: matter. The two analy-es, N..S. :>oi ami 

 :'.!'>, KTere made in accordance with the Texa- law rei:iilatiim tlie sale of 1'an- i.iei-u (see i'au r e'.l) 

 and other m-eetieidev and In. Ids ^,,,,,1 ,,iily until May 1 



