CARBONATE OF LIME. 137 
stone jug with water will make a sour vinegar, as the 
writer tested in his ranching days. Soil acids accu- 
mulate in soils that have no lime to neutralize them. 
Some plants grow well in sour soils, but not many 
useful plants. Wild things grow most in acid soils. 
Useful legumes grow poorly, if at all, with some ex- 
eeptions. And alfalfa refuses to grow at all with 
the soil sour. 
How is one to judge if his soil is sour? If he is 
experienced in soils he can tell by the character of 
plant growth on the land whether it is sweet or sour. 
Certain grasses betoken sour lands. Sorrel, or sheep 
sorrel (Rumex acetosellan) is pretty sure to come 
where there is lime deficiency, and sorrel and alfalfa 
do not go well together. There is a simple test that 
any one can make with litmus paper. This is a blue 
paper that can be bought of the druggist, usually in 
little slips, stoppered in glass bottles. One can take 
a slip of this paper and some of the suspected soil, 
having it moist, and insert half the length of the 
slip in the moist soil and let it remain in contact for 
half an hour. If there is any apparent redness in 
the paper be sure that there is acidity in that land. 
If the blue paper does not turn red the land is at 
least neutral. To test whether the land is actually 
alkaline with lime, which it ought to be to grow big 
alfalfa, expose a slip of the paper in quite weak 
vinegar only long enough to turn it red, then insert 
it in the soil and leave it for an hour, having the soil 
moist and in contact. If it then turns blue again 
you may be sure that you can grow it on that land. 
