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. 
Mendow gTass...25 02245. 2. os ae denials ae ee 72 
mediclover.2.. « wou oe a ale /erebeie 01a 'a ie’ ciate o\ef oe 79 
Maize, as used’ for fodder. ....2...2.6.-s0ce seen 81 
ACAD DEL Ceo 05 cine. c:Fn'b «oie 0,2 500 0 0i5:015, sole 4 2 ae eee 90 
IPOLALONTHDELS ...2 oi. . cara s es tes eo niaieion se sae 75 
UGA DOCS iwi. b Fale nieces boc duans ceo ee eee 82 
CALLOUS). «oie 5 o0stae's be Selegba ee wesc de aed a eee 85 
TL TDTLLTOS, foie iccs, anes, 0; oro'srs10.0,9in1 86, sia/eles jaa eae chee ae ie 91 
PING AVOOG 5... s/s 210) cracisadaaieanicciees . ano ee ean 40 
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 a 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 not 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 a water-bath, fig. 9, consisting of a vessel of tin or copper plate, 
with double walls, between which is a space that may be nearly filled 
with water. The substance to be dried is placed in the interior chamber, 
—re.™ 
