754 DR CHARLES HUNTER STEWART ON THE ESTIMATION OF 



The following blank experiments were undertaken to test the tightness of the 

 connections in the apparatus. The clips were arranged for sweeping out the whole 

 apparatus, the combustion flask was empty, and only one carbonic acid absorption 

 tube inserted. 



No. I. Experiment : — 



c.c.'s Oxalic Acid 

 Solution. 

 Original titre of } 



baryta solution j" 



c.c.'s Oxalic Acid 

 Solution. 

 After li hours' aspiration f 1st Titration, 41'5 c.c. ") 



i.i. i- i. i„ , at A* J- mean, 41'475. 



through apparatus, ( 2nd „ 41 45 c.c. J 



No. II Experiment : — 



c.c.'s Oxalic Acid 



Solution. 



Original titre of ) 



° ', = 46"15 c.c. 



baryta solution J 



c.c.'s Oxalic Acid 



Solution. 



After 3 hours' aspiration (1st Titration, 4 6 "05 c.c. ) ,»«,,.. 



... < _ , c#1 Vmean, 46-075. 



through apparatus, (_ 2nd „ 4b 1 c.c. J 



No. III. Experiment : — (Two absorption tubes used). 



c.c.'s Oxalic Acid 



Solution. 



Original titre of ) . . „ 



, ° . (■ = 4T9 c.c. 



baryta solution J 



After 4£ hours' aspiration ^ lgfc Titratiorij 41 . g5 cc _ 

 through apparatus, V 2nd 41-85 c.c. 



No. 1 tube, ) 



, 1st Titration, 4T9 c.c. 

 No. 2 tube, < 



' 2nd „ 41-9 c.c. 



{ 



These fairly fall within the error of experiment. 



Working error of the method. 



A large bottle was filled with Edinburgh main water and of it four samples of 

 500 c.c. each were analysed. The following are the results per 100,000. 





Organic Carbon. 



Organic Nitrogen 



No. 1, . 



0-3493 



0-0242 



» 2, . 



0-352 



0-0255 



» 3, . 



0-3412 



0-0232 



„ 4, . 



0333 



002306 



Mean, 



03439 



0-0240 



Percentage difference from mean of cases above mean and below mean. 



Carbon -f 1"92 per cent. — 2'03 per cent. 

 Nitrogen + 3-35 „ - 3-66 



