268 



ARTIFICIAL MANURES [chap, xiii. 



with the guarantee upon which he has bought Such 

 analyses are rarely necessary when dealing with 

 reputable merchants for such standard articles as nitrate 

 of soda, sulphate of ammonia, superphosphates, and 

 potash salts, but all residual materials like meat and fish 

 guanos and basic slag are subject to variations in com- 

 position which may not have been recognised by the 

 vendor. When a farmer purchases large quantities of 

 any of these articles it will always pay him to get the 

 deliveries checked by analysis. However, as the 

 material varies naturally, it is of the first importance that 

 the farmer should sample the bulk very carefully so as to 

 get a portion thoroughly representative of the whole. 



Table XXV.— Composition of Various Fertilisers. 



> Batiject to considerable Ttriatlon. 



