r 
Jellett — 0)1 Chemical ^Equilibrium. 515 
Second Experiment. 
A solution is prepared, containing quantities (carefully measured), 
of quinia and brucia. To a given bulk of this is added a certain 
quantity of hydrochloric acid, insufficient to neutralize both basis. 
The tubes of the saccharometer are filled, one with the unacidulated 
mixture, the other with the acidulated mixture. 
Putting now 
Ti = rotatory power of quinia. 
r.2 = rotatory power of brucia. 
/>! = rotatory power of hydrochlorate of quinia. 
p2 = rotatory power of hydrochlorate of brucia. 
r = actual rotation for acidulated mixture. 
a - total amount of acid corresponding to the unit of bulk of 
solution. 
X = amount which combines with the quinia — 
it is easily seen that 
a \ a J a \ a 
where /3i, /3^, a are the atomic weights of the two bases and the 
acid respectively, and J,, are the quantities of each base contained 
in the unit bulk of the solution. 
Solving this equation for x we have 
X = Aa + B {r - h^r^ - 52*^2); 
where 
_ ^2 {r, - Pa) 

A (^i - n) + A (r^ - p^) ' 
These constants are to be determined by a separate series of ex- 
periments. If To be the actual rotation caused by the unacidulated 
mixture, it is evident that 
Tq = h^ry + h^r^. 
The foregoing equation may, therefore, be written : — 
X = Aa ^- B (r - r^). 
This equation gives the quantities of acid, x and a - x, which are 
taken by the quinia and brucia respectively, 
II. I. A. PROC. — VOL. I., SER. II., SCIENCE. 3 X 
