1909.] Sale of Impure Sulphate of Copper. 



477 



The Board of Agriculture and Fisheries have on several 

 occasions drawn attention to the importance of using pure 

 sulphate of copper when making Bor- 



Sale of Impure deaux mixture, or when using it either 

 Sulphate of Copper. & 



for the destruction of charlock, for dress- 

 ing wheat, or for the cure of foot-rot in sheep. 



In purchasing it care should be taken to demand a 

 product of 98 per cent, purity, while the article offered as 

 " agricultural " sulphate of copper should be scrupulously 

 avoided. The usual adulterant is sulphate of iron, which is 

 much cheaper. An easy test for the presence of iron in sul- 

 phate of copper is to dissolve a little in water and add 

 ammonia, constantly stirring until a deep blue liquid is 

 formed. Any quantity of brown flocks floating about in this 

 blue liquid indicates the presence of so much iron that the 

 sulphate of copper should be subjected to a proper analysis 

 before use. 



During the past year the Board have had evidence that 

 impure sulphate of copper continues to be sold in considerable 

 quantities. Early in 1908 the Crown Agents for the Colonies 

 stated that certain wholesale chemists, in executing an order 

 for sulphate of copper for the Agricultural Department of one 

 of the Crown Colonies, sent sulphate of iron containing about 

 10 per cent, copper sulphate; and that in reply to the repre- 

 sentations of the Crown Agents, they stated that this was 

 the usual article supplied under the designation of sulphate 

 of copper for agricultural purposes. 



In consequence, 18 samples were purchased by Inspectors 

 of the Board from chemists in different parts of the country. 

 Of these 12 were commercially pure blue vitriol or sulphate of 

 copper. In two cases the description sulphate of copper or 

 blue vitriol was applied to articles containing 51*5 and 39' 2 

 per cent, respectively of sulphate of iron. In these cases the 

 Board directed inquiry to be made with a view to prosecutions 

 under the Merchandise Marks Acts. One sample described as 

 powdered vitriol contained 78*6 per cent, of sulphate of iron, 

 and was coloured with Prussian blue. Another sample de- 

 scribed as vitriolised wheat dressing contained 66 per cent, of 

 sulphate of iron, and two other samples sold under a fancy 

 name contained 76 per cent, and 56 per cent, respectively of 

 sulphate of iron. 



