272 PETER SPENCE 



premature, for after incurring heavy expense 

 the process had to be abandoned, and large 

 quantities of the mineral were thrown on his 

 hands. 



We may here suggest, and the suggestion 

 is the result of experience and experiment, 

 that if Mr. Spence had very finely ground 

 the Redonda and got it carefully tried by 

 some competent judges he would have found 

 that the natural phosphate of alumina by 

 itself, provided only that it was reduced to a 

 very fine powder or meal, would form a 

 phosphatic manure which would yield its 

 phosphoric acid to the crop in the course of 

 several seasons; and if mixed with sulphate of 

 ammonia, or nitrate of soda and a little potash 

 in the form of calcined Kainite, would have 

 been an excellent general manure. 



His manufacture of sulpho-cyanide of 

 ammonium was also an invention worthy of 

 note. He patented this first in 1863, and 

 completed it in 1864. In this process he 

 utilised the ammoniacal liquor from gas works, 

 drove off the volatile salts of ammonia, and 

 then crystallised the chloride of ammonium. 



The mother liquor he then diluted so as to 

 precipitate extraneous matters, and the clear 

 solution was taken for use. To this was 



