Superphosphates Fish Manures. 17 



phosphate, the adulteration of gypsum cannot be recognised by 

 simple inspection; and nothing short of a quantitative determi- 

 nation of the amount of gypsum can decide whether superphos- 

 phate has been adulterated with gypsum, or whether it contains 

 only the legitimate proportion which is produced in every in- 

 stance when bone-dust or burnt bones are digested with sul- 

 phuric acid. 



Desiccated Fish - Manure. Under this name a manure has 

 been sent to us for analysis, which was found to contain in 100 

 parts : 



Water saujn oil* 15-084 



Organic matter* <Of&M.j .. 19*643 



Soluble, or bi-phosphate of lime 10-478 



equal to bone-earth .. (16'345) 



Insoluble bone-phosphate 17"844 



Hydra ted sulphate of lime (gypsum) 27*552 



Alkaline salts 3'000 



Insoluble siliceous matter (sand) ,. 6'399 



100-000 

 * Yielding ammonia 1*490 



This manure, it will be observed, is in reality a superphos- 

 phate of excellent qualities, which was prepared by dissolving 

 fish-bones and other fish-refuse in sulphuric acid. 



Pilchard Refuse-Manure. The following analysis represents 

 the composition of the refuse-salt of pilchard fisheries : 



Composition of Pilchard Refuse-Manure. 



Water 5'725 



Common salt, with traces of lime, magnesia, and sul- 

 phuric acid 85-609 



Pilchard scales, with fish-oil and animal matter * .. 6-275 



Earthy impurities, principally calcareous shell sand .. 2*391 



100.000 



* Containing nitrogen .. -294 



Equal to ammonia '357 



A glance at these analytical results will show that this manure 

 contains about 85 per cent, of common salt, and 6 per cent, of 

 pilchard scales, which will yield on decomposition only '357 per 

 cent, of ammonia. Its commercial value, therefore, is not greater 

 than that of common salt (15s. to 18s. per ton), but inasmuch as 

 it contains some shell-sand, it may be applied in preference to 

 common salt to soils naturally poor in lime. 



Bone-Slack. A sample of bone-black, the refuse of a sugar- 

 refinery of Bristol, on analysis was found to contain in 100 

 parts : 



