Excerpt from Some Factors Influencing the Efficiency of Bordeaux Mixture

For the greater part Of the investigation the copper sulphate and lime used were what is commonly known as chemically pure. Dis tilled water was used in these preparations. Later, a number of the series were repeated in order to approach commercial conditions as closely as possible, using a good grade of common stone lime, com mercial copper sulphate, and tap water. The mixtures were prepared in glass-stoppered cylinders Of 1-lit'er Capacity graduated to divisions of 10 cubic centimeters. TO prepare Bordeaux mixture by allowing the two diluted components to flow simultaneously into the container, two burettes Of cubic centimeters capacity were placed side by side, with the outlets connected by rubber tubes provided with pinch cocks to a single Y tube, the lower arm of-which was so ar ranged as to project into the neck Of the glass cylinder. The proper quantity Of calcium hydroxid, made by slacking grams Of cal oium Oxid, was placed in one burette and diluted to half a liter, while in the other was placed a solution Of the same volume, con taining 5 grams Of copper sulphate. A current Of air was forced in at the bottom Of the burette containing the calcium hydroxid to keep the precipitate from settling out. If the two pinchcocks were opened at the same time the milk Of lime and the copper-sulphate solution flowed Simultaneously into the gradiiated receiver, and by properly manipulating the pinchcock either component could be added to the other. This apparatus was used in preparing all mixtures in which both the lime and the copper sulphate were diluted to the same vol ume before bringing them together. The comparative volumes Of the precipitates were determined-by measuring the fall Of the precipi; tate surface in the different mixtures during a given time interval, the graduations on the cylinders serving as convenient indexes for this purpose. The formula used in the preparation was usually that for 4 - 3 - 50 Bordeaux mixture (4 pounds of copper sulphate and 3 pounds Of lime to 50 gallons Of water) which is a standard formula for use on grapes and cranberries.

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