2 



3 



4 



Laminaria 

 saccharina. 



Highland 

 kelp. 



Zostera 

 marina. 



. 18-50 .. 



. 22-83 .. 



. 15-90 



. 20-11 .. 



. 18-38 ., 



. 16-37 



. 57-78 .. 



. 56-56 .. 



. 6536 



. 3-61 .. 



. 2-23 ., 



. 2-37 



300 THE MANUFACTURE OP KELP. 



20 per cent, of earthy phosphates. A few samples I have examined gave 

 me the following results : — 



1 



Laminaria 

 digitata. 



Phosphates of lime and magnesia.... 24-16 . 

 Carbonates of lime and magnesia.... 16 - 10 . 



Sand, &c 56-76 . 



Charcoal 2-98 . 



100-00 ... 100-00 ... 100-00 ... 100-00 

 The phosphates of magnesia predominate, and these are partially soluble 

 in water. The proportion of phosphate is about that in Peruvian guano, 

 and if the crude ammoniacal salt obtained by distillation were added in 

 the proportion of about 40 per cent., a manure would be obtained worth 

 from 107. to 127. per ton, of which from 3 cwt. to 4 cwt., would be sufficient 

 for an acre of land. The phosphate of magnesia it contains points to its 

 special application to beet-root and clover. Mixed with about 5 per cent, 

 of the chlorides of potassium and sodium, it would be equally beneficial to 

 other root and cereal crops. Liebeg divides crops, according to their wants, 

 into three classes — potash plants, lime plants, and silica plants ; such a 

 manure contains the food for all or either of these. 



6. The products of distillation I recommend to be treated as follows : — 

 The tar is syphoned off, and distilled with an equal measure of water in an 

 iron tar still ; the light volatile oil passes over with the condensed water, 

 on which it floats. This is decanted, and treated with a dilute sulphuric 

 acid, which removes picoline and other oily bases, and the red colouring 

 matter is deposited. This substance is washed and dissolved in spirit, and 

 the solution deposits it on evaporation. The light oil is then agitated with 

 from 5 to 10 per cent, of oil of vitriol, washed with water and caustic soda, 

 and finally re-distilled. The residual tar, from which the light oil has 

 been removed, is then pumped into another iron still, and a stronger heat 

 applied. The paraffin oil is thus obtained, and purified by oil of vitriol, 

 caustic soda, and re-distillation. The residual pitch may be employed for 

 the manufacture of patent fuel, &c, or pumped while hot into brick ovens 

 provided with an iron pipe to carry off the heavy vapours, and subjected to 

 a red heat, by which a further portion of paraffin oil is obtained, and a 

 good coke left in the still, commercially valuable to ironfounders on account 

 of its freedom from sulphur. The liquid in the condensers, being separated 

 from the tar, which sinks to the bottom, is mixed with excess of lime, and 

 distilled in a capacious iron still provided with a suitable condenser. 

 Ammonia and naphtha pass over, and are received into hydrochloric acid. 

 The solution of acetate of lime remaining in the still is run out, evaporated 

 to dryness, and the black, impure acetate thus obtained purified by charring, 

 re-crystallisation, distillation, or conversion into acetate of soda. The 

 ammoniacal distillate which has been neutralised by hydrochloric acid is re- 

 distilled till the specific gravity of the distillate rises to nearly that of water. 



