OXALIC ACID AND URANIUM SALTS AS A PHOTOMETER. 287 



Table IV shows that added acids or alkalies have no effect provided they do not 

 reduce the content of the solution in uranyl salt, as in number 16. With 

 ammonium oxalate the reaction practically proceeds at the same rate as with 

 oxalic acid. 



In the following tables the effects of various substances on the speed of the 

 reaction are noted, also that of the size of the vessel and the material of which 

 it is made. 



Table V. — Effects of various substances, and of the size and material of the vessel. 



[November 8, 1909. Manila. Sky partly overcast. Ten per cent oxalic acid solution, 

 1 per cent uranyl acetate solution.] 



Number. 



Oxalic 

 acid 

 solu- 

 tion. 



Uranyl 

 acetate 

 solu- 

 tion. 



Time. 



Other additions. 



Remarks. ■ 



Oxalic 



acid 

 decom- 

 posed. 



2. . 



cc. 



cc. 



10-50-11.05 

 10.50-11.30 

 10.45-11.30 

 10.45-11.30 



10.45-11.30 



10.45-11.30 



10.45-11.30 

 10.45-11.30 



25 cc. Kder's solution. 

 10 cc. Eder's solution. 

 10 cc. water 





Gram. 



0. 0105 

 .0931 

 .351 

 .360 



.01 



.01 



.309 

 .267 



3 









4 ' 



5. 



5.0 

 5.0 



5.0 



5.0 



5.0 

 5.0 



5.0 



5.0 

 5.0 



Control 



14 cc. water, 1 cc. 5 per 

 cent uranyl nitrate. 



15 cc. dilute, solution 

 of fluorescein. 



15 cc. ditute, solution 

 of eosin. 



10 cc. water 



10 cc. water . 



6 





7 





8 



In quartz beaker. 

 Flat dish open to 

 sun. 



9 



Table V shows that there is practically no difference between the nitrate 

 and acetate of uranium as accelerators of the reaction, that neither fluorescein 

 nor eosin alone have any effect on the decomposition of oxalic acid and that 

 the size and shape of the vessel markedly influence the rate of the reaction. 



Table VI. — Effect of various substances. 



[December 14, 1909, 10 a. m. to 1 p. m. Ten per cent solution of oxalic acid, 1 per cent 

 solution of uranium acetate. All made up to a volume of 20 cubic centimeters.] 



Number. 



Solu- 

 tion 

 oxalic 

 acid. 



Uran- 

 ium 

 acetate. 



Remarks. 



Oxalic 



acid 

 decom- 

 posed. 



5. 



cc. 



5 



5 

 5 

 5 



cc. 

 10 



10 



10 



Made faintly alkaline to phenolphthale'in 



with NaOH. 

 Made faintly alkaline to phenolphthale'in 



with KOH. 

 Made faintly alkaline to phenolphthale'in 



with NH 3 solution. 

 Control . 



Per cent. 

 











60 



6 . - 





8 



10 







Flasks 5, 6, and 7 had a decided yellow, opalescent appearance which indicated 

 that the uranium was present in some other form than uranyl acetate. 



