Food for Xhe question that presents itselt to the tarmer, gardener 



and truit grower is, Ho-iv can I supply my plants with ^itro- 



^ gsn, phosphoric acid and potash, in the best forms and at the 



least expense? We will trv to throw some light upon this 



question in the following pages. We will take first, 



Phosphoric Acid. 



T^, 1. • * -J There are two principal sources ot phos- 

 Phosphoric Acid. , . .. ^ ,^ , .^. 



phone acid, namely, bones and rock 



phosphates. Of these, the rock phosphate is the cheapest 



source. A prevailing impression exists that superphosphate 



made from rock phosphate is not as good as that made 

 from bones. It has been shown bv manv experiments that 

 this idea is entirely without foundation. What the plants 

 want is soluble phosphoric acid, and it makes little or no 

 difference from what source it is derived. 



The largest deposits ot rock phosphates exist in South 

 Carolina and Florida. These beds ot phosphate are sup- 

 posed to be composed of the petrified bones and excrements 

 of extinct animals. When this substance is ground and 

 mixed with a sufficient quantity ot sulphuric acid, the larger 

 part ot the phosphoric acid which it contains becomes 

 soluble in water. The knowledge ot this tact was one of 

 the greatest agricultural discoveries ot the age. 



When the rock phosphate is thus treated with sulphuric 

 acid, it becomes what is chemically known as superphosphate 

 of lime. The same is true if ground bone is treated in the 

 same way. A good example of superphosphate contains 

 14 per cent ot soluble phosphoric acid. 



p , The cheapest sources of potash are muriate 



of potash and wood ashes. 



Wood ashes, if unleached, contain from 3 to 5 per cent 

 of potash in the torm ot carbonate ot potash. They also 

 contain trom i to 2^2 per cent of phosphoric acid (insoluble). 

 They are worth, as plant food, from S~.oo to Si 2.00 per 

 ton, according to the amount ot potash and phosphoric 

 acid they contain. 



Muriate of potash is bv tar the most important source 

 of potash. It is tound in large deposits near Stasstort, 

 Germany, in what is called " Carnallite," which contains 

 about 15 per cent of muriate of potash. This is refined so 



