Chemistry and Physics. All 
5 ‘ " 
& mean value of i (c—c’); yet we see by representing specially the 
heat conveyed during positive and negative work, that this number can 
differ but little from the values of its expression as long as the excess is 
hot too small. If however there remains from a large amount of work 
only a small positive excess, it might be difficult to show that the pro- 
portional number could not differ considerably from the values of its 
expression. 
Finally if Mariotte’s law be not strictly accurate, we may put pote 
or pv and consider eas a small magnitude depending on p and v, 
which at the beginning of the motion is zero, In this case in place of 
pdv and vdp we shall have relatively 
eck st da eid oe 
pdv-+-7 dv; an ieee p- 
The last magnitude is cancelled and does not occur in the resulting 
equation. On the other hand g now becomes 
a | 
fs v. 
Were 9 of the form w(p)-+2(v) the quantity added to q would =y(v) 
and would vanish after the restoration to the original volume. In gen- 
bisulphid of carbon; on heating them to 150° C. they lose their bright 
