POTASSIUM SULPHOCAEBONATE. 127 



a propitious moment, which is exceptional. In all cases the direct 

 use of water suffices if the quantity be abundant, whether the soil be 

 compact, stony, or permeable, diffusion is always perfect. Alkaline 

 sulphocarbonate solutions of 1 in 10,000 and even 1 in 20,000 being 

 still poisonous in cultivation on the large scale, too great dilution need 

 not be feared, in rendering diffusion more perfect, to make the remedy 

 impotent. The best method of using sulphocarbonates consists in 

 making flat receptacles in the soil, round the foot of each vine, and 

 there distribute the poison. For this purpose 500 kilogrammes per 

 hectare (440 lb. per acre), say 50 grammes per square metre, are 

 diluted in 350 times its weight of water. After having poured the 

 solution into the excavations it is well to pour on a little water to 

 cause the poison to penetrate more deeply. "When all the water is 

 absorbed by the soil, the ground is put back into the pit and tramped 

 down under foot. Sulphocarbonates may be used at any time of 

 year, for the small dose has no effect on the plant, but it is prefer- 

 able to use them whilst the sap is at rest. The water required to 

 carry the poison into the depths of the soil being sometimes an 

 obstacle to its use in many districts, the most convenient time for the 

 application of sulphocarbonates is, then, that when rain is most 

 abundant during winter, when the soil is already saturated with 

 moisture. For small or medium scale cultivation, the best plan con- 

 sists in placing the amount of sulphocarbonate required for a stock, 

 say 50 grammes (1| oz.), in a 10-litre (2-2 gallon) watering-can, then 

 to pour into each pit the entire contents of this watering-can, and 

 afterwards pour an entire watering-can full of water on each slock. 

 But it is preferable when possible to make a dilute solution in a large 

 reservoir, and to draw out with the watering-can the amount required 

 for each stock. On the large scale, Mouillefert and Hembert have 

 designed plant intended to bring the water required for the treatment 

 into vineyards. It consists of a steam engine, working suction and 

 propelling pump which can send the water several kilometres, and to 

 a height of 100-150 metres (328-492 feet). The pump, placed near a 

 river or a lake, sends the water into a distributing channel forming a 

 network of ramifications through the vineyard. The channels of the 

 third order end in metallic vessels of 350-400 litres (77-88 gallons) in 

 which the sulphocarbonate is dissolved ; the workmen there draw the 

 amount of insecticide required, and spread it with the watering-can 

 around the stocks. With good organization the workmen need not carry 

 the water more than 10 metres, say 33 feet. A man can then spread 

 1500-1800 litres, say 330-396 gallons, of water an hour round the vines. 

 By this ingenious process, vines far from a source of water may be 

 treated. But owing to the large amount of water required, which is 

 150,000 litres per hectare, say 60,000 litres (13,200 gallons) per acre, 

 being awanting in many districts, this treatment has not been adopted 

 everywhere. Its use also finds a drawback in the fact that the cost of 

 sulphocarbonating is greater than sulphuring. It costs in fact 300-350 

 francs per hectare (120-140 francs, £4 16s.-£5 12s. per acre). It is true 

 that it brings potash to the value of 50 francs per hectare, 16s. an acre, 

 on to the land, but that is only really useful in districts where potash is 



