44 A GRICUL TURE. [en. 



injure it. It was first imported into England in 1839, 

 and at that time the supply in Peru was very large, 

 some of the beds being fully 200 feet in depth. Many 

 millions of tons have been exported since that time, 

 and the quality is not so good now as it used to be. 

 An average of fifty cargoes, imported into England 

 before 1855, contained nitrogenous matter equal to 

 rather more than 17 per cent, of ammonia. At the 

 present time, it may be taken as containing nitrogen- 

 ous matter equal to about 8 or 10 per cent, of 

 ammonia. Peruvian guano also contains a large 

 quantity of phosphates in an exceedingly valuable 

 form, and these add to its value. 



84. In 1864, Dr. Voelcker recommended the treat- 

 ment of Peruvian guano by the use of a small per- 

 centage of sulphuric acid, with the twofold object of 

 rendering the ammonia it contained non- volatile, and 

 for making the phosphates more quickly soluble in 

 water. The first was accomplished by the sulphuric 

 acid combining with the ammonia, and forming sul- 

 phate of ammonia. The second change arose from 

 the phosphate being converted into mono-calcic phos- 

 phate in the manner already described (68). This 

 treatment of Peruvian guano was commenced on the 

 continent in 1864, by Messrs Ohlendorff, and has 

 since then been very largely carried on in England - 

 the manufactured article being sold as "Dissolved 



..Guano." 



85. Sulphate of ammonia is another nitrogen- 

 ous manure which is very largely used in this country, 

 and which exerts as great an influence as a fertilizer 

 as the Peruvian guano, if not greater. This is pre- 

 pared from what was once known as the waste liquor 

 of gas works. It is a waste liquor no longer, as it is 

 carefully sought after for the production of sulphate of 

 ammonia. This manure is a white crystalline sub- 

 stance, more or less discoloured by impurities, and is 

 obtained by distilling the ammonia from the gas 



