OXALIC ACID AND URANIUM SALTS AS A PHOTOMETER. 285 



of the concentration of the two substances on the speed of reaction. 

 The results obtained are presented in the following tables : 



Table I. — Results ivith varying amount of oxalic acid and uranyl acetate. 



[Manila, October 21, 1909. Flasks exposed from 9.05 a. m. to 10.50 a. m. Sky partly 

 hazy. Temperature of air, 29°-30°. Temperature of solutions after exposure, 

 42°-43°.] 



Num"ber. 



Weight 

 uranyl 

 acetate. 



Weight 

 oxalic 

 acid. 



Water. 



Found 

 oxalic 

 acid. 



Oxalic 



acid 

 decom- 

 posed. 





Gram. 



Gram. 



cc. 



Gram . 



Per cent. 



1. _ _ ... . . 



0.0 

 0.05 



0.5000 

 0. 5000 



100 

 100 



0.495 

 0.34 



1 

 32 



2 



3 



0.10 

 0.15 

 0.20 



0. 5000 

 0. 5000 

 0. 5000 



100 

 100 

 100 



0.25 

 0.16 

 0.07 



50 

 68 

 86 



I 



4 



5 _ 



6„ — . . _ 



0.25 

 0.30 

 0. 35 

 0.40 

 0.45 

 0.50 



0. 5000 

 0. 5000 

 0. 5000 

 0. 5000 

 0. 5000 

 0. 5000 



100 

 100 

 100 

 100 

 100 

 100 



0.05 

 0.04 

 0.04 

 0. 045 

 0.05 

 . 0.05 



90 

 92 

 92 

 91 

 90 

 90 

 Gram. 





8. _ _ . _ 



9_ ... _ 



10.. 



11 _ 





12____ 



0.1 



0.1 



20 



0.14 



0.086 



13 



0.1 



0.2 



20 



0.026 



0.17 



14 



0.1 



0.3 



20 



0.097 



0.20 



15 



0. 1 

 0.1 

 0.1 



0.4 

 0.5 

 0.6 



20 

 20 

 20 



0.140 



0.26 



0.399 



0.21 

 0.24 

 0.20 



16 _ 



17 



18 



0.! 



0.7 



20 



0.486 



0.21 



19 



0.1 



0.8 



20 



0.599 



0.20 



20 _ 



0.1 



0.9 



20 



0.71 



0.19 



21 



0.1 



1.0 



20 



0.8 



0.20 



Flasks Nos. 1 to 11, in which the amount of oxalic acid was constant and 

 the per cent of the uranyl salt varied, demonstrated that each increment of 

 0.05 gram in uranyl acetate content increases the speed of the reaction by 18 

 per cent until the limit is reached in No. 5. In flasks Nos. 12 to 21, where the 

 amount of uranyl salt is constant and the oxalic acid is varied, except for 

 the minimum concentrations of oxalic acid in Nos. 12 and 13 the speed of the 

 reaction is constant within the limits of experimental error. These experiments 

 show that within very wide limits, the concentration of uranyl salt is the sole 

 factor in determining the speed of the reaction. Other experiments giving the 

 same general results are as follows: 



