54 HOW CROPS GROW. 
portions are not quite constant, even in the same part of different speci- 
mens of any given plant. 
WATER (per cent) IN FRESH PLANTS. 
Meadow grass 
Red clover..........++.05 . ene 
Maize, as used for fodder 
Cabbage ........ cee e eens Syrepatateta igs aia Sovraroat Ne areas we 
Potato tubers 
Sugar beets 
Carrots sediscasiniarmsinininawasiraernibnste se otae POEUN e es 
DAI MAA DS) ides. os aicierates geet eecransianerdvbisld wcbiows sus? Bi gie gta 
PING WOOdos.sucwieinasiaesicanieeeaey see yawne tr etidee de 
In living plants, water is usually perceptible to the eye 
or feel, as sap. But it is not only fresh plants that con- 
tain water. When grass is made into hay, the water is by 
no means all dried out, but a considerable proportion re- 
mains in the pores, which is not_recognizable by the 
senses. So, too, seasoned wood, flour, and starch, when 
seemingly dry, contain a quantity ‘of invisible water, which 
can be removed by heat. 
Exp. 21.—Into « wide glass tube, like that shown in fig. 2, place a 
spoonful of saw-dust, or starch, or a little hay. Warm over a lamp, but 
very slowly and cautiously, so as pot to burn or blacken the substance. 
Water will be expelled from the organic matter, and will collect on the 
cold part of the tube. 
It is thus obvious that vegetable substances may con- 
tain water in two different conditions. Red clover, for 
example, when growing or freshly cut, 
contains about 79 per cent of water. 
When the clover is dried, as for making 
hay, the greater share of this water es- 
capes, so that the air-dry plant contains 
but about 17 per cent. On subjecting the 
air-dry clover to a temperature of 212° 
for some hours, the water is completely expelled, and the 
substance becomes really dry. 
Fig. 9. 
To drive off all water from vegetable matters, the chemist usually em- 
ploys 2 water-bath, fig. 9, consisting of a vessel of tin or copper plate, 
with double walls, Let een which is.a space that may be nearly filled 
with water. The substance to be dried is placed in the interior chamber, 
