210 



Agricultural Gazette of N.S.W. 



[Mar. 2, 1920. 



The difference which appears to exist in the physical condition of the lead 

 .arsenates examined is shown not only b}' a variation in the size of the par- 

 ticles, but also by the weight of a given volume of the lead arsenate, or, in 

 other words, by the apparent specific gravity, which is recorded in the 

 table under the heading " weight per 100 c.c." The variation in weight 

 ranges from 36 in No. 8 to 123 in No. 7. Nos. 8 and 5 are the lightest (36 and 

 47). Nos. 7 and 4 are the heaviest (123 and 119), whilst Nos. 2, 6, 1, 3, and 9 

 .are intermediate, being 83, 88, 91, 97, and 112 respectively. 



The time tliut a lead arsenate will remain in suspension is a point worthy 

 ■of consideration. Other things being equal, any lead arsenate that separated 

 out immediately would be inferior for spraying to one in which the lead 

 .arsenate remaiied in suspension. 



Examination of Various Lead Arsenates obtainable in Sydnev, 



September, 1919. 



In the accompanying diagram the rate and amount of the settlement 

 which takes place is represented graphically. The various lead arsenates 

 were used at the strength recommended in Farmers' Bulletin, No. 72, viz., 

 " 18 oz. dry lead arsenate to 50 gallons water." The procedure was as 

 follows : The lead arsenate under examination was accurately weighed off, 

 and intimately mix:d with a small quantity of water, and afterwards 

 •diluted with water to the above standard. The whole was well shaken 

 and poured into a vessel with slo])ing sides, and the time and the volume of 

 the lead arsenate which fell in that interval of time recorded. From the 

 data obtained the graph has been constructed. 



