senate of lead can be mixed with Bordeaux mixture, very successfully, just 

 the same as Paris green. 



The investigation concerning the mixing Lime-sulphur with Arenate 

 of Lead was published by C. E. Bradley and H. V, Tartar (1) with the 

 following results in connection with further studies of the reaction of Lime- 

 sulphur solution and alkali waters on Lead Arsenate. Haedden has stated (2) 

 that Lead Arsenate is more soluble in water containing alkali salts than in 

 mineral waters. 



TABLE I. 



Composition of the Lime-sulphur Solution before and after addition of 

 Lead Arsenate. 



Grams per 1 0OOcc. Filtrate Filtrate from neut- 

 Blank from acid arsenate and ral Arsenate 



Lime-sulphur Lime-sulphur Lime-sulphur 



Total Sulphur 10.750 10.256 



" CaO 4.380 4.060 



" As2O5 .095 .012 



Above results indicate that 8 times as much arsenate is rendered soluble 

 from the acid arsenate as from the neutral, or calculated from original material 

 this would be equivalent to 0.25 percent, of saluble As2 O$ from neutral 1.98 

 percent. As2 Os from acid Lead Arsenate. Distinct losses of sulphur and lime 

 have also taken place in the acid arsenate mixture and it is evident that there 

 is a mutual decomposition when acid lead arsonate is mixed with the lime 

 sulphur solution. 



TABLE II. 

 Analysis of the residue from the Mixture of Lime-Sulphur and Lead Arsenate. 



Neutral Lead Arsenafe Acid Lead Arsenate 



residue residue 



Percent. Percent. 



Free Sulphur 0.70 20.80 



PbS 1.47 14.80 



CaO 10.40 



The reactions and loss of sulphur and lime from solution, as shown 

 above are much more pronounced with the acid than with neutral arsenate 

 and it is therefore advisable to employ the neutral form when desiring to com- 

 bine lime-sulphur and lead arsenate. Waters containing considerable quan- 

 tities of alkali carbonates should be avoided in mixing lead arsenate for spray- 

 ing purposer, as their tendency is to render the arsenic soluble and do not 

 dissolve the lead. Soluble arsenic is one of the most important things to avoid 

 as in most cases it is the main cause for the injury to foliage. 



(1) Journal Industrial Engineering Chemistry, Vol. II, No. 7, p. 328, (1910) 



(2) Bulletin 131 Colorado Experiment Station. 



