52 EXPERIMENTS WITH KEFERENCE TO THE POTATO DISEASE. 



This application was at the rate of 146 lbs. per acre. About 

 6 per cent, was diseased. 



Salt and Moberly's Sulphate of Magnesia. — Table I. 29, 

 30. For this experiment a compost was employed, consisting 

 of ^ lb, of common salt, ^ lb. of Moberly's sulphate of magne- 

 sia, mixed with '11 lbs. of earth, for 1 row. Moberly's sulphate 

 of magnesia is a rough sulphate from the alum works near 

 Whitby ; its crystals are large, and form rhombic prisms, whereas 

 the common sulphate of magnesia crystallizes in small quadran- 

 gular prisms. This rough sulphate i.s found to contain a little 

 free sulphuric acid. Tlie above compost was put in the drills as 

 manure, and then watered with 3 gallons of manure-water, dis- 

 tributed by means of a watering-pot. As soon as the manure- 

 water had soaked in, the potato-sets were planted on the compost. 

 The rates per acre of the application of the respective ingredients 

 were, common salt 2 cwt. 68 lbs., Moberly's sulphate of mag- 

 nesia 2 cwt. 68 lbs., earth 2 tons 17 cwt. 29 lbs., manure-water 

 1650 gallons. The amount of sound produce was nearly 2 cwt. 

 per acre greater than where salt alone was successively applied 

 to rows Nos. 26, 27 ; but the proportion di.seased was nearly 1^ 

 per cent, more than in those rows. 



Moherhfs Sulphate of Magnesia. — Table I. 31. The quan- 

 tity was ^ lb. mixed with the soil when the potato-sets wore 

 planted, being at the rate of 2 cwt. 68 lbs. per acre. The pro- 

 duce, estimated per acre, was 6 cwt. 34 lbs. less than in the 

 preceding experiment. This may have been owing to the ab- 

 sence of the eartli and manure-water. It was observed that. 

 where salt and sulphate of magnesia were applied, the proportion 

 diseased was nearly 1 \ per cent, greater than wiiere salt had been 

 successively applied. In all the rows to which salt alone was 

 given, the diseased portion averaged scarcely 6 per cent. In 

 this row, to which Moberly's sulphate of magnesia only was 

 applied, the proportion diseased was 12i per cent., or more than 

 double that of the rows which had common salt. 



Sets dipped in Lime. — Table I. 32. The sets were dipped 

 in hot slaked lime, and were then planted with all the lime 

 that adhered to them. The proportion diseased was 7/5- per 

 cent., — not half the quantity diseased in the next row, where the 

 sets were merely sprinkled with lime. 



Sets sprinkled with Lime. — Table I. 33. The sets being 

 placed in the drill, powdered unslaked lime was dusted over 

 them. The quantity was 2 lbs. to the row, being at the rate of 

 10 cwt. 46 lbs. per acre. The very large proportion of 17 '27 

 per cent, was diseased. More lime was used than in the pre- 

 ceding experiment. When the sets in both rows were about to 

 be covered up, there was quite as much lime visible upon the 



