ON THE ESSENTIAL CONSTITUENTS OF MANURES. 39 



of burnt clay, it retarded the germination of the seed and the growth of the 

 turnips in their first period of existence. Several other experiments, made 

 on a small scale, and all my experiments upon turnips in 1858 and in 1859, 

 confirm the fact first observed by me in 1855, that sulphate of ammonia, 

 instead of rapidly pushing on the young plant, as generally supposed, retards 

 its development in a very marked degree. 



The produce of each plot was taken up on the 19th of November; after 

 trimming and cleaning, the roots were weighed. The following Table gives 

 the produce in Swedes, topped and tailed, and cleaned per acre, and increase 

 per acre : — 



Plot. ■ • tons. 



1. 3 cwt. of superphosphate 10 



2. 3 cwt. of bone-dust 8 



3. 3 cwt. of superphosphate, made by 



dissolving bone-dust in 50 per 



cent, sulphuric acid 9 14 3 1 ... 3 3 



4. 3 cwt. of purchased bone-superphos- 



phate 9 



5. Unmanured 6 



6. 1 \ cwt. of sulphate of ammonia .. 5 



7. 1| cwt. of sulphate of ammonia and 



\\ dissolved bone-ash 9 



8. 1| cwt. dissolved bone-ash 8 



9. 4 cwt. of gypsum 6 



10. 9 cwt. of burnt clay 6 



11.3 cwt. of Peruvian guano 8 



Plot 1, it will be seen, yielded the largest increase ; from first to last this 

 plot had the lead as to appearance. 



The superphosphate used in this experiment had the following composition: — 



Moisture 10*80 



Organic matter * 4'21 



Biphosphate of lime 20'28 



Equal to bone-earth made soluble by acid. . (31*63) 



Insoluble phosphates 4*1 1 



Hydrated sulphate of lime 46*63 



Common salt 10'78 



Sand 3-19 



100-00 



It will be seen that there is very little nitrogen in this superphosphate, and 

 that in addition to much soluble phosphate it contains about 11 per cent, of 

 common salt. Salt, I am inclined to think, increases the efficacy of phos- 

 phates upon turnips. 



Plot 2. The bone-dust used upon this plot was as fine as sawdust, and 

 yielded on analysis, — 



Moisture 6*86 



Organic- matter f. 13*14 



Phosphates of lime and magnesia .... 68*17 

 Carbonate of lime 679 



Alkaline salts 1*90 



Sand 3*42 



100*00 



• Containing nitrogen -34 t Containing nitrogen 1-83 



Equal to ammonia '41 Equal to ammonia 2*22 



