310 Manurial Properties of Clay from Gas-Works. 



of a fungus, and z/ sulphur in some or all of its combinations be a 

 preventive, and if carbonic acid and arsenic (both of which exist 

 in small quantity in the clay) prevent its attacks or its growth, 

 we may account for the prevention in this particular case ; but 

 where the whole subject is" so entirely beyond the limits of our 

 present knowledge, it appears more becoming to hesitate in the 

 expression of opinion. What is certain is, that the attacks of 

 disease, and of course the presence of a fungus, could be traced 

 down the stems below the eartli to the tubers, where it stopped 

 when these were in contact with the gas-manure, and to which it 

 extended in all other cases. But an isolated instance does not 

 prove that we have here a specific against disease, nor even that 

 the action of the same agent will be the same on other soils and 

 under other circumstances. Trials alone can do this, and trials 

 in sufficient number to warrant an induction. What happened 

 is interesting and suggestive, but I could not advise any one on 

 this ground alone to employ the manure for his potato crop in 

 any other than an experimental manner. If a manure for this and 

 the following crops oi a rotation is required, the question is altered; 

 the blue clay may be applied with confidence where the object 

 sought is fertilisation, and not insurance against disease. 



Perhaps I may be excused for indicating in conclusion the 

 position I sliould like to see occupied by the stranger whom I 

 have introduced to British agriculturists. Its position is that of 

 an auxiliary, not of a supplanter, — an aid to the production of 

 more food, and not a substitute for something already employed 

 for that purpose. The two great agricultural wants of our 

 country are more grass and more root crops, which are insepa- 

 rable fiom more meat and more bread ; and, if permitted to have 

 a voice in the application of the new home-produced fertiliser, I 

 should like to see it employed as far as possible in these two 

 species of production. The national advantage will thus be most 

 advanced, and it will be a source of satisfaction to feel that, 

 while the general good has been promoted and increased support 

 provided for our pressing population, a benefit has been conferred 

 upon an interest which is at the basis of national prosperity, and 

 upon a class of men who are second to none in the qualities 

 which make good citizens. 



St. Andreto^s, Wahefield, December, 1857. 



