24 
Garden Work 
slag and sulphate of ammonia are mixed, the lime, which is 
largely present in the basic slag, will unite with the sul- 
phuric acid of the sulphate of ammonia, forming sulphate 
of lime, and the ammonia — i.e. the plant food — will be 
liberated in the form of gas, and thus entirely lost. Again, 
we have a similar loss if we mix nitrate of soda with super- 
phosphate. The sulphuric acid of the superphosphate will 
drive out the nitric acid of the nitrate of soda. 
Similarly, we should not mix superphosphates with basic 
slag, as the soluble phosphates will unite with more of the 
free lime of the basic slag, and will be rendered almost 
entirely insoluble, therefore useless as far as the plant is 
concerned. Again, basic slag should never be mixed with 
guano, or ammonia will be liberated and lost. It is there- 
fore better to use artificial or chemical manures separately. 
The plants are then more certain of getting the full manu- 
rial value. 
There are some expensive manures which fully repay 
the gardener for his outlay. They have the additional 
advantage of being made up in convenient quantities for 
the small grower. They can also be obtained in tins which 
are practically air-tight, and therefore prevent any loss of 
the valuable qualities. 
