(525) 
The percentage of water contained in crystallized indican is 
therefore : 
) 
I 14.3 pCt. 
II 15.4 pCt. 
FIE 142 OE 
the formula C,, Hi, NO, + 3 HO requires 15.5 pCt. 
Chemical Laboratory of the Polytechnical School. 
Mathematics. — “A special case of the differential equation of 
Monee.” by Prof. W. KAPTEYN. 
To the communications inserted in the Proceedings of Noy. 25th 
and Dec. 30t 1899 we here add the results of our investigation 
of a case where the equation of MonGs consists of three terms. 
If the equation of Monge has the form 
stiAttu—o 
this equation will admit of two intermediate integrals, only when 
eer 1 
roe, ee) , hr 
where g represents any function of 2,y,z,g, and the function w 
satisfies the differential equation 
nA. d 
and H denotes the operation — +g— . 
dy de 
Then one of the intermediate integrals is 
petv=f(e, 
where f denotes an arbitrary function, the second being found by 
conneeting the two integrals of the complete system 
