Experiments upon Swedes. 21 



of superphosphate with nitro-phosphate without stating the 

 composition of both, since nitro-phosphate is only a commercial 

 name occasionally given to manures, which are essentially super- 

 phosphates ? I have seen published accounts of experiments 

 with superphosphate, blood-manure, nitro-phosphate, and am- 

 monia-phosphate, and with mixtures of these manures ; but had 

 the author of those experiments known that blood-manure is but 

 a name that applies to artificial manures which in nine cases 

 out of ten are in reality superphosphates, and that nitro- 

 phosphate and ammonia-phosphate often hardly contain any 

 nitrogen or ammonia, but are nothing more or less than super- 

 phosphate, he would have modified his experiments, or at any 

 rate given the reader some clue as to the character of the manures 

 with which he experimented. 



Plot I. Manured with phospho-Pemvian guano, No. 1, at the 

 rate of 3 cwt. per acre. 



Produce ...... 9 tons 6 cwt. 2 qrs. 18 Ibs. 



Increase per acre . . 2 tons 14 cwt. 3 qrs. 22 Ibs. 



The swedes looked remarkably healthy until the beginning of 

 September, when they were attacked by mildew and made but 

 slow progress. 



Composition of Phospho-Peruvian Cruano, No. 1. 



Moisture .................... 11-84 



* Organic matter and ammoniacal salts ........ 10' 35 



Bi-phosphate of lime .............. 11'88 



Equal to bone-earth, rendered soluble by acid .. .. ( 18-54) 



Insoluble phosphates .............. 29*32 



... { Phosphoric acid . . 13'51 > 



containing :{ Lime * ........ 15>81 } ;.; 



Hydrated sulphate of lime ............ 25'47 



Alkaline salts, containing '21 phosphoric acid .. .. 4'77 



Magnesia .................. '86 



Insoluble silicious matter (sand) .......... 5'51 



100-00 



* Containing nitrogen 2*09 



Equal to ammonia 2'34 



Percentage of phosphates, rendered soluble by acid .. .. 18'54 



, , of insoluble phosphates, calculated as bone-earth 34-25 



Total phosphates, calculated as bone-earth .. 52'79 



It will be seen that this and the other samples of phbspho- 

 Peruvian guano are very valuable manures that are distinguished 

 from othej fertilizers by a high percentage of phosphates, a 

 large proportion of which is rendered soluble by treatment with 

 sulphuric acid. 



The insoluble phosphates in this guano are composed for 

 the greater part of two equivalents of lime and one equivalent of 



