DIVISION OF CHEMISTRY 263 



SESSIONAL PAPER No. 16 



guarantee on the label, stating percentage of lead arsenate present and particulars 

 as to soluble impurities. This practice is to be commended as furnishing the pur- 

 chaser information required in. making sprays of any desired strength and in allow- 

 ing him to judge of the relative values of the various brands offered for sale.* 



AGRICULTURAL BLUESTONE. 



This compound, a crystalline mixture of the sulphate of copper and sulphate of 

 iron, is frequently sold for bluestone or sulphate of copper, to which it is distinctly 

 inferior in the treatment of wheat for the destruction of smut. Further, it is worth- 

 less for the purpose of making Bordeaux mixture, the common use of bluestone by 

 orchardists. Some years ago there was a considerable amount of this compound on 

 the market in the Canadian Northwest and we warned our readers against purchasing 

 it, as the fungicidal power, as shown by our experiments, was very materially reduced 

 by th9 presence of the sulphate of iron. For sometime past no samples have been 

 received at the laboratories, but one was forwarded a few months ago from Arm- 

 strong, B.C., which bad been sold as bluestone. This sample, (Laboratory No. 13550), 

 proved, on analysis, to contain 77-05 per cent of sulphate of iron. Subsequently a 

 similar sample was forwarded by another correspondent from the same district and 

 was found equally impure. 



Bluestone has a deep blue colour (it may be slightly effloresced on the surface 

 due to loss of water of crystallization) and if to its solution in water a slight excess 

 of ammonia is added, the precipitate that at first forms dissolves entirely, the solution 

 being intensely blue. Agricultural bluestone may be recognized by its greenish ht» 

 and by tbe fact that on the addition of ammonia to its solution a dirty, yellowish- 

 red precipitate of hydrated oxide of iron persists. The term ' agricultural ' as applied 

 by the trade to this compound, is misleading; there is no use in agriculture in which 

 it is not inferior to bluestone — and for some purposes, as for Bordeaux mixture, it ia 

 worthless. 



CARBOLIZED WHEAT PROTECTOR. 



This preparation made by G. B. Clark, Woburn Sands, England, is sold for the 

 treatment of wheat, oats and barley for the destruction of smut, and consequently 

 comes into competition with the two well-tried remedies, (bluestone and formaldehyde). 

 It is also stated to act as a preventative against ' rust, bunt and mildew and the 

 ravages of slugs, wire-worms, and the attacks of birds and other farm pests.' It is 

 a reddish powder, smelling strongly of carbolic acid. Its analysis afforded the follow- 

 ing data : — 



Anah/sis. 



Per cent. 



Sulphate of iron 71-89 



Sulphate of copper 25-93 



Crude carbolic acid -56 



Red ochre 40 



Mineral matter insoluble in acid -61 



Undetermined -36 



10000 



It is not at all probable that the use of this compound, which is practically 

 ' agricutural bluestone,' with a little carbolic acid and coloured with ochre, would 

 prove as effective for the treatment of wheat as either of the chemicals now in common 

 use. For smut destruction, the value of carbolic acid in dilute solutions is extremely 

 doubtful ; such evidence as we have "would appear to be distinctly adverse to its suc- 



* A chapter of the physical and chemical properties of arsenate of lead, together with an 

 account of the 'neutral' and 'acid' forms found on the market, will be found in the Report 

 of the Chemical Division, 1912. 



