TllK NATURALISTS' COMRANION. 
187 
Ty tUe liydroL-liioric acid uniting with 
the lime in the ealeite, freeing the ear- 
honie acid, wkieh escapes in bubbles. 
This is called elfer\x‘scence. As cal- 
cite is the only mineral that elferves- 
ces 1‘reely with cold dilute hydrochloric 
racid, it is very easy to distinguish. 
Chilcite is so slightl}' dissolved by 
w'ater that it is tasteless. Fifteen 
hundred parts of water are required to 
dissolve one of calcite. Water contain¬ 
ing carbonic acid disolves calcite 
much more readil3^ This is notice¬ 
able in the formation of caves in lime- 
.stone, which are formed by the lime¬ 
stonebeing dissolved by water contain¬ 
ing carbonic acid. 
If calcite be kept at a red heat for 
•several hours, the carbonic acid is 
<lriven out and pure lime is left. The 
;stone will be half as heavy as orrigin- 
ally. Limestone that has been treated 
in this manner is called quicklime. If 
•tested with h^xlrochloric acid in the 
same manner as the calcite was, it will 
not etlervesce. This is because there 
is no carbonic acid in the mineral to 
■escape. 
The cominouest method of burning 
lime in a lime kiln, is to build a furn¬ 
ace, either round or square, with an 
opening at the base to manage the lire. 
At lirst large pieces of limestone are 
piled in the form of an arch, leaving a 
place for the tires, and then the stone 
is thrown in loosely over this arch. 
After the heat has driven out the car¬ 
bonic acid, the hres are put out and 
the quick lime is taken out. 
If water be added to the<piick lime, 
it will swell, burst into a powder, and 
grow hot, and although water has been 
•added it is still quite dry. The water 
has united with the lime, forming slak¬ 
ed li.me-. It quick lime is exposed to 
the air, it takes up moisture and be¬ 
comes air-slaked. If the quick lime 
is slaked with enough water it forms 
white-wash, which is veiy useful. On 
standing, part of the lime will settle, 
leaving pure lime water, which is a 
saturated solution of lime; that is, the 
water contains all the lime it can dis¬ 
solve. One hundred parts of water 
will dissolve one of pure lime; and as 
fifteen hundred parts of water are re¬ 
quired to dissolve one of calcite, pure 
lime is much more soluble. If a per¬ 
son blow s into some lime w'ater through 
a straw, the water will become cloudy, 
then milky, and finaly some fine wLite 
powxler will sink to the bottom of 
the glass. This is caused by the car¬ 
bonic acid in the person’s breath unit¬ 
ing wdth the lime in the water, forming 
carbonate of lime or calcite, which is 
not so easily dissolved as pure lime, 
therefore the wnter cannot contain as 
much calcite as pure lime, and thecai- 
cite is deposited as a fine powder. 
TO BE CONTINUED. 
In o, 000,000 years the mean annual 
temperature of the earth wdll have de¬ 
creased thirt3^ degrees, and eventuall}^ 
the terrestial hemisphere wdll be froz¬ 
en up, according to the latest astrono¬ 
mical computations. It makes one 
shiver to think of it. 
-o- 
Iligli winds are sometimes a surprise 
to birds as wxll as to men and beasts. 
A long-legged sand hill crane wuis tak¬ 
ing a na)) by the side of a pond in the 
zoological garden in Thiladelphia, 
wdien a mighty g’ust of wind struck 
him squarely and knocked him into 
the water. He came up dripping and 
wdien the crowxl laughed he sneaked 
awun' to a loneh' corner. 
