Intelligence and Miscellaneous Articles. 149 



Atmospheres. Hydrogen. Air. 



60 0-9810 1-0131 



80 1-0118 



90 1-0106 



100 0-9552 1-0098 



125 0-9442 1-0062 



150 0-9372 1-0047 



175 10027 



200 0-9158 0-9990 



225 0-9078 0-9862 



250 0-9001 0-9792 



275 0-9599 



300 0-8761 0-9465 



325 0-8670 0*9230 



350 0-8537 0-9047 



375 08929 



400 0-8347 0-8672 



450 0-8136 0-8265 



500 0-7893 0-7927 



550 0*7701 0-7502 



605 0-7580 0-7215 



660 0-6895 



705 0-6660 



The above results were obtained by operating on 43*638 cubic 

 centims. at +15°. 



It appears, according to these numbers, that Mariotte's law is not 

 verified for high pressures ; each gas in contracting seems to follow 

 a special course. Hydrogen decreases regularly ; air, on the con- 

 trary, very curiously, reaches a maximum at 80 atmospheres, and 

 afterwards decreases more rapidly than hydrogen. 



In presenting these still very incomplete experiments to the Aca- 

 demy, I simply wished to record them, reserving to myself the time 

 necessary for their execution. 



I am at present occupied in pursuing my determinations with 

 much higher pressures, and extending them to other gases. — 

 Comptes Rendus, May 23, 1870. 



NOTE TO MR. MOONS PAPER ON THE SOLUTION OF LINEAR PAR- 

 TIAL DIFFERENTIAL EQUATIONS OF THE SECOND ORDER, IN 

 THE PHILOSOPHICAL MAGAZINE FOR JULY. 



I desire to point out that when the coefficient U in the equation 

 0=Rr+Ss+Tt + Pp + Qq + Uz 

 is finite, the assumptions 



c=l, c l = c 2 = &c. =0 



materially cripple the generality of the result ; as a glance at the 

 mode in which each of the coefficients A., A 2 , &c. is formed from its 

 immediate predecessor will readily show. 

 July 23, 1870. 



