110 THE FARMERS 5 HANDBOOK. 



through the filter, rinsing it out with water so as to get all the sand on the 

 paper. The paper with the sand is now placed in the oven until quite dry, 

 and weighed. If a second filter-paper of the same size as the first be placed 

 in the other scale the weight obtained will Represent the weight of sand. 

 This should not be more than 3 or 4 grains in a pure bonedust. This number 

 divided by two will give the percentage of sand and insoluble matter in the 

 bone-dust. 



The filtered liquid is now neutralised with ammonia — that is to say, 

 ammonia is added till the solution turns red litmus paper blue. Allow the 

 precipitate which is formed to settle and filter again in the same way as 

 the sand ; dry and weigh as before. The weight of this precipitate 

 divided by 2 gives the percentage of phosphate of lime in the bonedust. 

 This should not be less than 40 per cent. — that is, the precipitate should weigh 

 at least 80 grains. The above scheme does not pretend to scientific accuracy, 

 but it will give a fair approximation to the actual composition. 



As the efficiency of a bonedust depends much upon the fineness of division, 

 it is as well to grade it roughly by passing it through a sieve with twenty- 

 four meshes to the linear inch. Three-quarters of the weight of the manure 

 (75 per cent.) should pass through the sieve. 



It must be thoroughly understood that the above tests are only intended' 

 as a rough guide as to the purity of a manure. If the quantity of impurity 

 is found to be excessive a sample should be forwarded to a qualified analyst- 

 for report. 



General Remarks on Artificial Manures. 



Manure the crop, not the land. 



Never purchase a manure without a guarantee of its composition as; 

 determined by analysis. 



In the case of complete fertilisers, it must not be forgotten that you have 

 to pay for getting them mixed; consequently it is often a question whether it 

 would not be cheaper to buy the simple manures and mix them yourself. On 

 the other hand the mixing (especially in the case of large quantities) can be 

 much more thoroughly done by the manufacturer. 



The simple manures are bonedust and superphosphates, containing nitrogen 

 and phosphoric acid (superphosphates from mineral phosphates contain no 

 nitrogen) ; dried blood, sulphate of ammonia, and nitrate of soda, containing 

 principally nitrogen ; sulphate of potash, and wood- ashes, containing potash ; 

 and lime, gypsum, &c, containing lime. As these fertilisers are seldom used 

 in greater quantities than can be mixed by hand, the trouble involved is 

 very small. 



A further advantage is that you can vary the proportions to suit your own- 

 particular requirements in different cases, whilst in purchasing a complete 

 fertiliser you nearly always pay for a quantity of some ingredient which you 

 do not require. 



It will be found more convenient to mix them with about three times their 

 weight of dry loam, and distribute evenly. The advantages of such a course 

 are obvious. Lime should not be added to ammonium sulphate, or dried 

 blood, or bonedust, as it drives off ammonia. It is safer not to add lime to 

 any nitrogenous manure ; hence, when the land has been limed, it is better 

 not to manure it for two or three weeks. 



