XII.] IMPORTANCE OF ANALYSIS 351 



are, from their mode of origin, subject to variations of 

 composition which may escape the notice of the vendor 

 himself. As regards the pure unmixed fertilisers, 

 standard articles made on an enormous scale, such 

 as nitrate of soda, sulphate of ammonia, superphos- 

 phate, kainit, and sulphate of potash, any farmer 

 dealing with a reputable firm may count on getting 

 what he pays for, because these materials do not vary 

 in composition except they have been deliberately 

 falsified after they have left the wholesale hands. 

 But with basic slag, guanos, fish, meat, and bone 

 compounds, so many different samples exist of varying 

 composition, and so easily may even a single cargo 

 show differences in passing from one part to another, 

 that the farmer will be always wise to check his 

 purchases by an analysis, not of course of the sample 

 that may be submitted to him before purchase, but of 

 the consignment on arrival. 



The farmer should buy his fertiliser on the strength 

 of the analysis or guarantee which he must get from the 

 vendor before he gives his order, and on which he 

 should work out a valuation by the method described 

 earlier in the chapter ; he must then be careful to see 

 that the invoice agrees with the guarantee on which he 

 bought, and check the invoice by getting an analysis 

 made of a sample drawn from the bulk delivered. But 

 in both his own interests and those of the vendor the 

 farmer must take some trouble over the sampling; a 

 good many of the disputes that arise between the two 

 parties are due to careless sampling or to the storage 

 of the sample afterwards where it can lose or gain 

 moisture. 



In order to exercise to the full his power of buying 

 in the cheapest market prevailing, it is clearly necessary 

 for the farmer to know with some exactitude the kind 



