Bulletin Volume 71-100 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt: ... be dissolved in cold water use a large amount of water and suspend it near the upper surface of the water, in a basket, coarse sacking, or any other receptacle through which water may pass readily. Copper sulphate should not be dissolved in iron vessels, as it corrodes them very rapidly. Buying Copper Sulphate. It is best to buy copper sulphate in sufficient quantity to get wholesale rates for it may be kept from season to season without injuring its value. Weighing and Straining the Lime. When the mixture is used in power spraying machines with stationary nozzles it should be run through a sieve so as to take out all particles that might clog the nozzles. When hand pumps are used straining will not be necessary if care is used in pouring the lime. The amount of lime necessary to form the Bordeaux mixture was formerly determined by weighing, using two-thirds as much lime as copper sulphate, but by means of the color tests as explained below the necessity of weighing the lime is now obviated. Excess of Lime. It is important that enough lime be added, otherwise the mixture may injure the foliage, while an excess of lime will not harm the foliage. Color tests. Various color tests may be used for determining whether or not sufficient lime has been added to the copper sulphate solution to form the Bordeaux mixture, as explained in Bulletin 84 of this Station. The one most commonly known is the potassium ferrocyanide test which is used as follows: Pour the lime into the copper sulphate solution, stir the mixture thoroughly and then add a drop of the potassium ferrocyanide. If enough lime has been added the drop will not change color when it strikes the mixture, otherwise it will immediately change to a dark reddish brown color. More lime must then be added till ...