LIMESTONE 303 
of the earth was at one time buried beneath the waters of the 
ocean. The difficulty of realising this fact would to a large extent 
be removed if the child actually discovered for himself some of the 
evidence on which it rests. 
It is not recommended that the naming of the numerous speci- 
mens be made a matter of special attention—and this also applies 
to fossils—though names should be given where possible, as they 
provide an easy and convenient means of referring to what has 
already been done. The primary object should be to examine and 
describe the rocks, not to find names for them. Collecting as an 
aid to Rock-study is of such importance as to become almost a 
necessity—but collecting as a substitute for Rock-study can only 
result in very little real good being done. 
It is hardly necessary to add that the rocks to be studied first 
are those in the immediate neighbourhood of the school. These 
are the ones which should receive most attention. Specimens 
obtained from a distance will prove a valuable aid in expanding 
and reinforcing what has already been done—that is, their 
investigation should follow that of local specimens. 
It should be borne in mind from the outset that the work 
suggested here is not Geology, but is to be undertaken with the 
object of questioning Nature, observing her methods and answers, 
and of generally encouraging a spirit of enquiry. 
XIV.—LIMESTONE. 
Limestone may be defined as a mass of Calcium Carbonate, 
sometimes nearly pure, when it is soluble in Hydrochloric 
Acid, and sometimes loaded with Sand, Clay, or other 
impurities. Few rocks vary more in texture or com- 
position—it may be hard and close-grained showing con- 
choidal fracture, or a crystalline rock composed of 
erystals of Calcite—or a dull, earthy, friable mass. In 
colour, too, it varies considerably—the most common 
shades being blue-gray passing to white. 
A great deal of Limestone occurs in New Zealand, so that 
it should not be a difficult matter to secure plenty of 
