42 



THE COMMERCIAL AND AGRICULTURAL 



COMPOSITION OF SUPERPHOSPHATE OF LIME. 



It will be observed how greatly these samples differ in compo- 

 sition, and, consequently, also in relative value. 



Nos. 1 and 2 are both good superphosphates. 



No. 3, on the other hand, is much adulterated with sand and 

 gypsum, and contains only 5'61 per cent, of soluble and G'8 per 

 cent, of insoluble phosphate of lime. 



No. 4 is richer in soluble phosphate, but mixed with a great 

 deal of gypsum, aud scarcely worth half the money at which it 

 was sold. 



No. 5 is a superphosphate manufactured by a maker, of 

 Wellington, who calls this poor manure, containing only 7'37 

 per cent, of soluble and 1'56 of insoluble phosphate of lime, with 

 1 % 42 per cent, of ammonia, an ammonia phosphate, although 

 it contains less ammonia than many samples of ordinary super- 

 phosphates. 



It cannot be surprising that men who have the impudence to 

 ask 67. per ton for such a superphosphate as that mentioned 

 under No. 5 can have the impertinence to tell agriculturists that 

 of all crops turnips require least phosphate in a manure, and that 

 therefore a superphosphate containing much soluble and inso- 

 luble phosphate is not a valuable manure for root-crops. 



The MAYOR (who occupied the chair at the lecture delivered at Barnstaple) 

 announced that discussion was invited on the subject of the lecture, and that 

 the Professor would have much pleasure in answering any questions which 

 might be put to him. 



Mr. R. GREGORY (guano merchant) expressed his pleasure in listening to the 

 excellent lecture. The lecturer had admitted that guano was most congenial 

 to the wheat plant, and superphosphate for the turnip crop. That doctrine he 

 had of late heard disputed ; but whether those who entertained a contrary 

 opinion had been labouring under a delusion or not it was difficult to say. 

 Many gentlemen present contended that guano was more congenial and more 



