EXPERIMENT STATION RECORD. 



Vol. XXIII. Abstract Number. No. 8. 



RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



On the composition of lime-sulphur spray, H. V. Tartar and C E. Bradley 

 {Jour. Indus, and Engin. CJiem., 2 {1910), No. 6, pp. 211-211). — From the re- 

 sults of the work the authors conclude that " simple and accurate methods for 

 the determination of the composition of the polysulphids and the amount of 

 calcium hydroxid have been perfected. Free dissolved calcium hydroxid is not 

 a constituent of the lime-sulphur solution, its alkalinity being due to the 

 liydrolysis of the polysulphid. The polysulphids in the solution are probably a 

 mixture of the tetrasulphid and pentasulpbid of calcium. [The] tests show 

 the absence of appreciable quantities of hydrosulpbid. Should any be preseut, 

 it is that which might be formed by the hydrolysis of the polysulphid. There 

 seems to be a more stable polysulphid of calcium which the results indicate to 

 be CaS2. A considerable amount of the sulphur in the solution is very feebly 

 combiuod and for practical spraying purposes may be considered as sulphur in 

 physical solution. It is not necessary for the spray to oxidize in order that 

 free sulphur may be deposited from the same. Prolonged boiling when approxi- 

 mately one part of lime to two parts of sulphur are used causes an increase in 

 the amount of polysuliiliids and a decrease of thiosulphate. Carbon dioxid 

 reacts with the lime-sulphur solution, liberating hydrogen sulphid. [The] 

 laboratory experiments indicate that the carbon dioxid of the air exercises some 

 influence in the decomposition of the spray upon the tree." 



Further studies of the reactions of lime-sulphur solution and alkali waters 

 on lead arsenates, C. E. Bradley and II. Y. Tartar {.Jour. Indus, and Engin. 

 Chem., 2 {1910), No. 1, pp. 32S, 329).— -'It appears from . . . the results that 

 both forms of the lead arsenate are more soluble In saline waters than in pure 

 waters. Alkaline carbonate waters especially exert a solvent action on these 

 arsenates and the reaction is much more pronounced in the case of the acid 

 arsenate. This is perhaps due to the fact that lead carbonate is extremely in- 

 soluble and that a base with which arsenic forms a soluble salt is present. It is 

 evident that waters containing considerable quantities of alkali carbonates 

 should be avoided in mixing lead arsenate for spraying purposes, as their tend- 

 ency is to render the arsenic soluble. Tests for lead in the alkaline solutions 

 failed to show its presence therein." 



The phosphates of calcium, F. K. Cameron and .T. M. Bell {Jour. Amer. 

 Cheni. Soc, .i.i (1910), No. 7, pp. 869-813). — The increasing importance of the 

 phosphates of calcium in the fertilizer industry led the authors to study their 



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