292 CHEMICAL MANUEES. 



This fish manure, which is in great part delivered to the farmer 

 as it is, is also used at Kernevel in the manufacture of com- 

 pound manures and in that of phospho guano. The chief compound 

 manure, which is sold under the name of Breton Manure, is merely 

 fish cake mixed with a sort of fucus (seaweed) extracted at low 

 water. As to the phospho guano, it is manufactured by treating the 

 crushed fish cake with sulphuric acid of 50" B. Next morning it 

 forms a paste and ends by diying. It is advantageously used for 

 different crops, particularly for beets. It contains on an average 2 '5 

 of nitrogen. In Brittany the sardine industry commences at 

 Croisic and ends at Douarnenez; it yields about 6000 barrels of 

 sardine heads ; a barrel of 225 litres contains on an average 30,000 

 heads. 



Manufacture of Fish Guano in Norway. — At the present day 

 fish guano is manufactured chiefly in Newfoundland and on the 

 islands of the Norwegian coasts. The most important factories of 

 this manure are in the Lofoten Isles to the north of Bergen. The 

 fishing industry, which is very important in the North Sea, and 

 the flesh of which is sold under the name of cod, yields a very 

 abundant raw material ; the head, the fins, the intestines, etc., are 

 utilized. Norwegian fish guano perceptibly resembles steamed bone 

 dust, although it does not occur in the same pulverulent form as 

 the latter. The process generally used is the same as that for 

 making bone dust. The fish debris is steamed, dried, and ground ; 

 steaming presents certain difficulties. When the digester described 

 on page 264 is used, the material cakes so that the steam cannot 

 pass through it ; steaming is therefore too strong on the edges and 

 the material is too much degelatinized, whilst the centre escapes 

 steaming. To remedy this di^awback, the firm of M. Friedi^ich of 

 Plagwitz, near Leipzig, has built a horizontal digester, an interior per- 

 forated cylinder revolving around an exterior cylinder. The material 

 to be treated is fed into the interior cylinder ; it is heated by steam 

 which is injected into the exterior cylinder ; then a rotary motion 

 is imparted to the first, the effect of which is to turn the material 

 over unceasingly and to renew the surfaces in contact with the 

 steam. The gelatinous solution is separated through a tap at the 

 bottom of the apparatus, and it is evaporated to transform it into 

 solid gelatine. After cooking, the material contains a rather large 

 proportion of water. That is why the material is dehydrated before 

 passing it to the drying machine by passing it through either a 

 hydraulic press or a centrifugal machine. A greasy liquor is thus 

 obtained which separates a little oil on standing. The dry material 

 is crushed in the same way as bones. For some years back fish 

 guano has been treated by sulphuric acid. It contains on an average 

 7-9 per cent of nitrogen^and 12 to 16 per cent of phosphoric acid. 

 The following are the analvses of several Norwegian guanos: — 



