POTATO CULTURE ON FARMS. 87 



Bordeaux mixture is extending rapidly. It is not only a 

 valuable preventive to disease, but also a means of pro- 

 longing the life of the haulm, and thus increasing the 

 yield. It does not give absolute immunity from disease, 

 but greatly reduces the injury. The mixture consists of 

 201b. of sulphate of copper, and either lOlb. or 201b. of 

 quicklime in 100 gallons of water. The larger quantity of 

 lime is preferable, as it insures the neutralizing of the 

 acidity in the sulphate of copper, and does away with the 

 necessity of testing. When the smaller quantity of lime 

 is used, the testing of the mixture with a piece of litmus 

 paper is of importance. If the paper turns red when 

 dipped in the solution more lime must be added until it- 

 is found to retain its blue colour on dipping it. The copper 

 sulphate is dissolved with hot water in a wooden vessel, 

 and the lime is slaked in another. When the lime has 

 been sufficiently liquefied, it is strained through a sieve 

 of the finest brass wire gauze into the other solution. 

 After further dilution to make up 100 gallons, the mix- 

 ture is strained into the spraying machine. Bordeaux 

 mixture should not be made until it is required, as it 

 deteriorates by keeping. Some authorities state that it 

 should not be kept for over forty-eight hours. A ready- 

 made dry mixture, known as Strawsonite, which will keep 

 for any time in its dry state, is manufactured by Messrs'. 

 Strawson, of Queen Victoria Street, London. It is dearer 

 than the sulphate of copper and lime, but saves much 

 disagreeable work. Messrs. Strawson make excellent 

 spraying machines for potatoes. One is an independent 

 machine, which sprays seven rows of potatoes at a time, 

 and gets over 25 acres in a day. It contains 100 gallons, 

 and is drawn by two horses. Another, which contains 60 

 gallons, sprays five rows at a time. A third is a five-row 

 sprayer, which can be worked from an ordinary farm 

 cart, and costs much less than an independent machine. 

 This machine is either worked by a man standing in the 

 cart, or by gearing attached to one of the cart wheels. 

 Twelve to fifteen acres a day can be sprayed with this 



