2 
THE YOUNG SCIENTIST. 
abled thus to decompose carbonic acid. During 
the nig-ht they give off a part of the carbonic 
acid which they absorbed during the day, and 
which for want of light, they are unable to de- 
compose ; and therefore it has been held that 
plants must be injurious when kept in sleeping 
rooms. 
But while it is quite true that plants give off 
carbonic acid during the night, the extent to 
which they do this is so slight, that it may be 
safely overlooked, especially when we remem- 
ber that there are so many other agents of far 
greater power, at work in the same direction. 
A common Student lamp gives off more carbon- 
ic acid during the night than would a whole 
houseful of plants. Even a candle will give 
off more than would be exhaled by all the 
plants in the conservatory of the most ardent 
lover of flowers. A child, breathing for five 
minutes, will throw off more carbonic acid than 
a windowf ul of plants would do in a week, and 
yet who ever was afraid of staying in the room 
with a child? The injury which even a large 
collection of plants is capable of doing to the 
air is as nothing compared with that to which 
the presence of a strong, healthy man 
gives rise. Indeed if there were any 
foundation for fear on this L3Core, a 
greenhouse or conservatory would, 
towards morning, become one of the 
most deadly places a person could en- 
ter ; yet . who ever felt inconvenience 
from a walk through a conservatory 
in the early morning ? And how re- 
freshing is the air of such an apart- 
ment when compared with that of a 
ball-room where the dancers have 
been in active exercise, and conse- 
quently have consumed the oxygen 
with more than ordinary rapidity ! 
We may therefore safely conclude 
that on this ground, there is no valid objection 
to the presence of plants in sleeping or living 
rooms. 
There are, however, certain plants which 
give off powerful odors, and which should be 
carefully avoided. It is impossilfle to give a 
list of plants which are objectionable on this 
score, for it has been found that different con- 
.stitutions are differently affected in this respect 
— plants which are entirely harmless to some 
being almost deadly to others. The rule ought 
therefore to be to exclude all plants which give 
off a strong odor, either through their leaves or 
flowers. If this rule be strictly adhered to, no 
danger will be incurred. 
The Art of Bust-Modelling and Casting. 
BY ADELAIDE F. SAMUELS. 
THE first day you can do nothing but prepare 
the clay, which can be procured at any 
Italian image-caster's shop for two or three 
cents a pound, and fifty pounds will be suffi- 
cient to make a life-sized bust, with drapery. 
Preparing it, or setting it up for the bust, is 
the only disagreeable feature in modelling ; 
all artists agree to that. 
The clay is set up in the following manner : 
Wet the top of your modelling-stand — if you 
have not one with a revolving top, an old shoe 
box on end will answer the purpose — then with 
a wooden mallet, pound upon it your clay, 
piece by piece, until you have a solid mass, 
icithout flaws, as high and as broad as you 
intend your bust to be. The clay must be 
neither too wet, nor too dry, but just moist 
enough to cling readily together. 
Now, if you are quite sure your clay is well 
pounded, you can cover it with a wet cloth and 
leave it over night to shrink, while you take a 
Fig. L— Tools used in Modelling in Clay. 
look at some of the tools you will require, most 
of which can be made by any smart boy or girl, 
but if you prefer to buy them, they can be pro- 
cured at the image-caster's, where you bought 
the clay. 
Tool No. 1 is mostly used to get a level sur- 
face on the clay, by drawing the teeth repeat- 
edly over it in opposite directions. It can be 
easily made out of hard wood. 
No. 2 is also made out of hard wood, and is 
used to get a polished surface by pressing the 
spoon-like end upon the clay, and working the 
tool about in little circles; it is also used to 
'• dig " with. 
NO. 4. 
