110 KCONOMICAL GEOLOGY. 



be almost pure crab, there being scarcely any charcoal or 

 other absorbent material in it. The slight loss which may 

 have been in the analysis is involved in the organic matter. 

 The ammonia was determined by an ultimate analysis. It 

 does not exist in the cancerine, ready formed, but the 

 nitrogen, from which ammonia is generated, is in it ; and in 

 accordance with the common practice of chemists, the 

 amount of ammonia which the nitrogen will produce, is 

 calculated. 



Another specimen of the crab shells, unmixed with other 

 matter, and only dried in the air, gave 10.78 per cent, of 

 ammonia. Two other specimens of the cancerine gave 9.22 

 and 9.77 per cent, of ammonia. The phosphoric acid in the 

 last two was 3.87 and 4.24 per cent. The analysis of the 

 single specimen is retained rather than the average of the 

 three, as it is understood to be the intention of the manu- 

 facturers to send the dried and ground crab material into 

 market without the addition of deodorizers or absorbents. 



The establishment of this manufactory has been the 

 subject of much interest. The increasing use of concen- 

 trated manures, the continued reports of their early ex- 

 haustion, and their enhanced price, has drawn the atten- 

 tion of the public to other sources of supply ; and every 

 honest attempt to meet this want should meet with public 

 encouragement. The agricultural value of the cancerine, 

 and its price compared with that of Peruvian guano, may 

 be estimated. The following table gives the highest, the 

 lowest, and the average composition of thirty-two well 

 authenticated specimens of Peruvian guano. It is copied 

 from " Morton's Cyclopedia of Agriculture." 



