290 BACON. 



No. 6, Table V, had already shown that fluorescein did not have this effect. Table 

 X shows that 0.1 gram of uranyl acetate accelerates the reaction approximately to 

 ten times the rate observed with oxalic acid alone, and also demonstrates that 

 phenol, aniline, malachite green and methyl violet, like fluorescein, protect the oxalic 

 acid from the rays of the sun, probably by preventing the latter from penetrat- 

 ing far into the solution. The experiments of Table XI, prove that small 

 amounts of alkaloids act as marked poisons in this catalysis. The results 

 agree with those found in my previous paper, ,s but it was thought necessary to 

 repeat them, using the titration method, first making the solution alkaline, 

 and removing the alkaloid with ether before the titration, as it was considered 

 possible that in the earlier experiments the alkaloids might have held back 

 some of the gas, the volume of which was used as a measure of the amount 

 of decomposition of the oxalic acid. The following experiment serves as further 

 confirmation of the poisonous character of alkaloids in this instance. 



Two flasks connected with eudiometers were put in the sunlight as follows: 



1. Five cubic centimeters 10 per cent oxalic acid, 5 cubic centimeters 1 per cent 

 uranyl acetate solution, 10 cubic centimeters 10 per cent sulphuric acid. 



2. Same solutions with 0.1 gram cinchonine. 



No. 2 gave 25 cubic centimeters of gas during the time that flask No. 1 gave 

 45 cubic centimeters. 



The effect of temperature on the rate of decomposition of oxalic acid by uranyl 

 salts is shown by the following : 



1. November 19, 1909, Manila, (a) Five cubic centimeters oxalic acid, 10 cubic 

 centimeters 1 per cent uranyl acetate, at boiling temperature, (b) Same solu- 

 tion at 30°. From 10.45 a. m. to 11.05 a. m. both solutions lost 0.062 gram oxalic 

 acid. 



2. Two flasks each containing 10 cubic centimeters 10 per cent oxalic acid 

 and 10 cubic centimeters 1 per cent uranyl acetate solution. Both exposed to 

 the sunlight, side by side. Flask A equipped with a reflux condenser and kept 

 boiling and Flask B heated only by the sun. Final temperature 44°. A. 0.127 

 gram oxalic acid decomposed; B, 0.130 gram. 



These experiments indicate that this reaction over a wide range has no 

 temperature coefficient. 



According to Fay, 10 Jones found that a very small amount of uranyl oxalate 

 will decompose a very large, if not an unlimited quantity of free oxalic acid, if 

 exposed continuously to the direct sunlight. 



The experiments which I made on this point are as follows : 



1. Ten cubic centimeters 1 per cent uranyl acetate solution, 10 of 10 per cent 

 oxalic acid solution. After a week's exposure to the sun, the green color of the 

 solution has entirely disappeared and there is only a grayish precipitate. Titra- 

 tion shows practically no oxalic acid left in the solution. In this experiment 0.1 

 gram of uranyl acetate has decomposed 1 gram of oxalic acid, and there is no 

 indication that the limit has been reached. 



2. Twenty-five cubic centimeters 10 per cent oxalic acid solution ; 10 of 1 per 

 cent uranyl acetate solution. When the limit was apparently reached, 1.18 grams 

 oxalic acid had been decomposed. 



15 Loo cit. 

 10 Loo. cit. 



