Report of Society's Meetings. 185 
In Clark's " Manual of Rules, Tables and Data" page 405, the eva- 
porative power of 1 pound of dry megass is given as 7 pounds of water ; 
and if we suppose it capable of evaporating -f of 7, or 4I pounds in 
practice, what will be the effect of moisture if present to the extent of 
50 per cent ? To evaporate 1 pound of self-contained water the useful 
evaporation will be reduced from 4-§ to 3f pounds, or 22 per cent, and 
this when the combustion is presumed to be equally perfect in both 
cases, a very unlikely occurrence. 
From the same authority, page 444, I find the total heat of combus- 
ion of dry megass is 7 792 units, and in the manner shown, page 407, can 
calculate that 3*219 units of heat raise the total products of combustion 
i°, from which their specific heat, 247 is found by dividing 3*219 by 13, 
the weight of the products ; also by dividing 7792 by 3*219 = 2*424°, 
we get the temperature of combustion. When 1 pound of water is 
associated with 1 pound of megass, 1*116 units (total heat of steam) are 
appropriated to evaporate the water, leaving 7*792 — 1116 = 6*676 units 
of heat available for raising the temperature of the gases. 
To raise the direct products 1° there are required 3*219 units. 
And to raise the water (as gaseous steam) 1° -475 units. 
Total to raise mixed products 1° 3*694 units. 
Then the units of heat available divided by this, that is 
6*676 -"-3*694= 1*807°, gives the temperature of combustion of megass 
holding 50 per cent, moisture, which is only 74 per cent, of 2*424°, that 
of dry megass. 
Now let us study the total units of heat with those effective after 
deducting the loss due to the escape of the gases, at some 500° above 
the normal temperature. As before, 1 pound of dry megass yields 
7792 units, but, as it requires 3*219 units to raise the produces of com- 
bustion i°, there are lost 500 x 3 - 2i9— 1*609 units, leaving 7792 — 
1*609=6" 1 83 units as effective. Now, with the 2 pound sample of 
megass containing 50 per cent, moisture, we have already seen there are 
but 6*676 of heat available, and 3*694 units are required to raise its 
mixed produces i°, consequently there are lost 500 x 3*694=1 847 
units, leaving 6*676 — 1*847=4*829 units as effective. So here again, 
we see the effectiveness is reduced to 78 per cent, of that of dry megass. 
From this it would appear that megass holding 50 per cent, mois- 
ture (about the best result obtained from the heaviest mills) should 
theoretically burn, in its green state, with but a loss of 22 per cent, of 
its evaporative power ; but in practice, such a favorable result can not 
