The Potato. 73 



gas water, with nitric acid (the worst of all); xiitiate of potass ; 

 nitrate of soda; — all gave unfavourable results. 



Antiseptic and other chemical manures, such as chloride of 

 lime, iodide of potass, charcoal (fresh) in fine powder, charred 

 sawdust, burnt clay, peat ashes in their usual state, though 

 costly in price, were tried at three separate periods in each year, 

 with only negative results. If they did not render the disease 

 harmless, they did not aggravate it. From the curative success of 

 the flour of sulphur in numerous vineries, and its effect in 

 checking the propagation of the disease in very many greenhouse 

 and conservatory plants, 27 yards of ground were measured out 

 and divided into three beds, each 9 yards long and 1 yard (or pole) 

 ■ wide. Three drills of potatoes ran the whole length in the centre 

 iif each compartment ; the drills being 30 inches apart, and the 

 sets in the drill 20 inches from each other. Between these drills 

 there were two rows in which cabbage plants were grown. 

 28 lbs. of flour of sulphur were divided into three equal propor- 

 tions ; and in bed No. 1 tliis quantity was strewed over the sets 

 Avhen planted in the trench, and then covered over in the usual 

 manner with earth. In bed No. 2, similarly treated, some 

 recently-slaked lime was superadded on the sulphur. In bed 

 No. 3 a peck of lime was mixed with a good quantity of water, 

 and whilst still very hot had the other portion of sulphur 

 stirred up with it ; and then, the water being augmented to 

 9 gallons, one-third portion of the mixture was let run out from 

 the spout of a 3-gallon watering-pot on the sets in the trench, and 

 then all were covered up as before. The trendies were made about 

 4 or 5 inches in depth. 1'hese experiments, although varied greatly 

 in detail and on ditFerent soils, were very inconclusive, as was 

 1 cwt. of flour of sulphur sown broadcast over three-quarters of 

 cin acre of potatoes as soon as any appearance of the disease was 

 manifest. Neither did any better result appear from mixing 1 cwt. 

 of flour of sulphur with 1 hogshead of recently-slaked lime, and 

 used as before. Nor was the result more conclusive from mixing 

 28 lbs. of sulphur with a quantity of lime in a cask, filling it up 

 with 90 gallons of water, and drawing off the clear solution, 

 mixing 1 quart of it with a watering-pan not quite full (about 

 Tj gallons) of soft water, and sprinkling it with a coarse rose over 

 a similar quantity of potatoes. Having taken up the idea that a 

 deficiency of soluble silica, which forms the outer coating or 

 envelope of every vegetable production, might prove a very great 

 predisposing cause to the ravages of the disease, and seeing that 

 it was always communicated to the under side of the leaf, ivherc 

 there is not one-third -part of the silica that the upper side of the 

 leaf possesses, a hundredweight of silicate of potass was ob- 

 tained from Manchester, and boiled in soft water until the 



