Wisconsin State Horticultural Society / Annual report of the Wisconsin State Horticultural Society for the year 1910
Volume XL, Part II (1910)
Richards, M. W.
How to make Bordeaux mixture, pp. 150-153 PDF (937.1 KB)
WINTER MEETING. 153 solution will be lumpy. In using these stock solutions for the 4-4-50 formula 4 gals. of each are taken and diluted to about 10 or 15 gal. This dilution is done because it has been found that the materials when mixed in a concentrated form make a poor mixture and the resulting Bordeaux does not remain in sus- pension well. The diluted Copper Sulphate and lime are then poured into a third vessel through a gunny bag sieve and the result is Bordeaux. Another way of making up stock solutions is by using a satur- ated solution of copper sulphate. This solution is obtained by using enough of the sulphate in the gunny bag which is sus- pended in the stock barrel so that the solution will become sat- urated. It has been found that 1 gal. of a saturated solution oj at the average temperature contains 3 lbs. of sulphate. The lime stock solution is made up by slaking no definite amount of lime and making up to no definite amount in the stock barrel. The mixture is made by taking 1 1-3 gal. of the sulphate solu- tion diluting it and mixing it with an amount of diluted stock lime. The resulting mixture is then tested with potassium ferro-cyanide or as it is commonly called yellow prussiate of potash. When a few drops of the potassium ferro-cyanide is dropped on the mixture if an excess of copper is present a dark brown precipitate will be formed. More lime should be added if this brown precipitate results. When enough lime has been added to neutralize the effects of the copper no brown precipi- tate will result upon adding potassium ferro-cyanide. The ad- vantages of this method of procedure are that it is less trouble to make the stock solutions and that they will keep indefinitely with no danger of their changing strength. In conclusion I will mention a few precautions to be exer- cised in the preparation of Bordeaux Mixture. 1st. Use good materials. 2nd. Do not use air-slaked lime. 3rd. Do not mix in a concentrated form. 4th. Do not use metal utensils. 5th. Always test mixture for free copper. 6th. Always make according to some well established formula. If these precautions are observed satisfactory Bordeaux is sure to be obtained.
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