REPORT OF TEE CHEMIST 185 



SESSIONAL PAPER No. 16 



At the time of writing this report experiments are in progress in conjunction 

 with the Horticultural Division to ascertain the relative efficiency of these sprays 

 from an insecticidal standpoint. We have proved by actual trial that all the sprays 

 described may be used without fear of injury to the foliage of apple and i>otato. If 

 we may assume that arsenic in the form of arsenite of lime is as effective for 

 irsecticidal purposes as that in Paris green, then these newly proposed sprays will be 

 cheaper than those containing Paris green — for white arsenic is quoted at 13 cents to 

 17 cents per lb., while Paris green varies from 21 cents to 30 cents per lb., according 

 to quantity purchased. The diiJerence in price of the arsenic in these two chemicals 

 is greater than even the above figures indicate, for the equivalent in arsenic of 1 lb. 

 white arsenic is 2 lbs. of Paris green, making the arsenic in Paris green approximately 

 four times as expensive as that in white arsenic. 



COMMERCIAL BORDEAUX MIXTURES. 



Analyses have been made of several brands of Bordeaux paste and Bordeaux 

 powders upon the market. The consensus of opinion among fruit growers appears 

 to be that the freshly prepared mixture has proved a more efficient fungicide than 

 the commercial preparations, and there is little probability from the present outlook 

 that the practice of making the Bordeaux mixture in the field, as at present in vogue, 

 is likely to give way to the use of the factory-made product. The results of this work 

 will, however, be of interest to many of our readers, as numerous inquiries have been 

 received regarding the nature and strength of these commercial preparations. 



Grasselli's Bordeaux Mixture Paste. — (Laby No. 6760) is a smooth thick paste 

 of a pale blue colour. It contains 62-43 per cent of water, the equivalent of 15-38 

 per cent of sulphate of copper and 22-30 per cent of slaked lime. 



In the preparation of the paste a sufficiency of lime has been used to precipitate 

 all the copper, and hence the resultant spray should be non-injurious to foliage. 

 Compared with the home-made mixture prepared from the commonly used formula, 

 4:4:40, the dilution of this paste according to the printed directions of the manu- 

 facturers would result in a much weaker spray. 



Vanco Bordeaux Mixture Paste. — (Laby No. 7007.) This is manufactured by 

 the Chemical Laboratories, Ltd., Toronto, and is a brownish creamy paste. Its 

 analysis showed 40-48 per cent water, the equivalent of 24-94 per cent sulphate of 

 copper and 24-81 per cent of slaked lime. There was no free copper sulphate present. 

 This paste, it will be observed, is considerably stronger than No. 6760, just described. 



CamphelVs Improved Bordeaux Mixture (Laby No. 6613) comes in the form of 

 a powder and is virtually a mixture of sulphate of copper and carbonate of soda and, 

 hence, is properly speaking a Burgundy Bordeaux. Its composition is 62-03 per cent 

 sulphate of copper and 33-38 per cent carbonate of soda. On the addition of water 

 there would be no copper sulphate left in solution. 



Grasselli's Bordeaux Mixture Powder (Laby No. 6763). — This is a true lime- 

 Bordeaux, and consists of a mixture of anhydrous sulphate of copper and quick lime 

 in the proportion of, approximately, 50 parts of the latter to 30 parts of the former. 

 It is intended to be used only in the dust form. 



Bordeaux-Lead Arsenate Mixtures. — These preparations are intended to act as a 

 combined insecticide and fungicide. Two samples have been analysed, both products 

 of the Grasselli Chemical Company, with the following results : — 



Laby No. 6761 — Grasselli's Bordeaux-Lead Arsenate Paste. — A smooth, thick, 

 light-blue paste. 



Laby No. 6762 — Grasselli's Bordeaux-Lead Arsenate Powder. — A very finely- 

 ground bluish powder. 



