﻿34 



RTLLKTIX 1147, l\ S. liKTA KT M i;.\T OF AGRK 'ULTURE. 



plus Bordeaux mixture), 42.8; sample 51 (sample 69 plus lime- 

 sulphur), 41.8; sample 23 (commercial zinc arsenite), 51.4; and 

 sample 54 (sample 23 plus Bordeaux mixture), 46. From these 

 figures it seems that both Bordeaux mixture and lime-sulphur 

 decreased the toxicities of the arsenicals used. Since silkworms and 

 honeybees refuse to eat food containing lime-sulphur, the experi- 

 ments in which they were used are not reported. All the other larvae 

 enumerated ate only about 25 per cent as much food as did the con- 

 trols, while those that fed on foliage sprayed only with Bordeaux 

 mixture and lime-sulphur ate 83 per cent and 54 per cent, re- 

 spectively. Neither Bordeaux mixture nor lime-sulphur used alone 

 had much insecticidal value against the insects tested. 



In 1920 these experiments were repeated. Different arsenicals 

 were tested, but the Bordeaux mixture (4-3.67-50) and lime-sulphur 

 (1-30) were of the same strengths. The Bordeaux mixture and 

 arsenicals were so mixed that each dry spray material consisted of 

 practically 22 per cent of arsenious or arsenic oxid, and when the 

 necessary amount of water was added, each had an arsenic or 

 arsenious oxid content of 0.076 per cent. Table 15 gives the ana- 

 lytical results on these spray materials before water was added. 



Table 15. — Composition of Bordeaux mixture alone and in combination with arsenicals. 



Sample 

 No. 



Material analyzed. 



Mois- 

 ture. 



Arsenious 



(As 2 3 ) or 



arsenic (AS2O5) 



oxid. 



Base. 



Carbon 

 dioxid 

 (C0 2 ). 





Total. 



Water- 

 soluble. 



61 



Laboratory sample of Bordeaux mixture 

 (4-3.67-50). 



Sample 61 plus acid lead arsenate (39) 



P.ct. 

 \ 0.6S 



.24 



.57 

 15.64 



.37 



} .46 



P.ct. 



P.ct. 



Per cent. 

 115.90 (CuO) 

 \54.49 (CaO) 



5.60 (CuO) 

 ■{18.16 (CaO) 

 142.52 (PbO) 

 / 9.09 (CuO) 

 \53.10 (CaO) 

 / 6.63 (CuO) 

 \22.70 (CaO) 



7.07 (CuO) 

 ^24.22 (CaO) 

 31.38 (ZnO) 

 ("30.55 (ZnO) 

 \ 8.92 (CaO) 



P.ct. 

 \ 3.52 



I 1.17 



| 5.29 



} 



\ 1.95 



91 

 92 



22.06 

 22.30 

 22.16 



23.05 

 24.33 



0.12 



.26 

 16.81 



.23 



.38 



55 





54 



Sample 61 plus zinc arsenite (23) 



30 



Commercial Bordeaux and zinc arsenite mix- 

 ture. 



} ■« 



Table 16 shows the average percentages of toxicity against web- 

 worms and tent caterpillars of lead arsenate and of calcium arsenate 

 alone, with Bordeaux mixture, and with lime-sulphur, and of sodium 

 arsenate and zinc arsenite alone and with Bordeaux mixture. 



