470 T. M. Chatard — The determination of Water, etc. 



gave 4028 per cent Na 2 equivalent to 28*58 per cent CO, 

 required to make Na 2 C0 3 ; 3S*13-28*58 = 9*55 per cent C0 2 as 

 the acid C0 2 of the bicarbonate present. Hence 0*09 per cent 

 of this C0 2 was not driven off. 



In another sample of Urao from same locality : 



Salt taken. 



Loss of salt. 



H 2 0. 



Diff.=CO a . 



C0 2 in Res. 



Sum CO 



1-1801 



29-27 



19-80 



9-47 



28-69 



38-16 



1-2297 



29-35 



19-83 



9-52 



28-64 



38-16 



1-2066 



29-39 



19-85 



9-54 



28-49 



38-03 



1-0880 



29-26 



19-80 



9-46 



28-67 



38-13 



1-1761 29-32 19-82 9*50 28*62 38-12 



Two determinations total C0 2 gave 38*17 per cent and 38*22 

 per cent, average 38*19 per cent C0 2 ; two determinations of 

 alkali gave 40*19 and 40*22 average 40*20 per cent Na 2 

 equivalent to 28*53 per cent CO„. Hence as 28*62 per cent 

 C0 2 was found in the residue we have 0*09 per cent acid 

 C0 2 not driven off. 



In a sample of Trommsdorff's C. P. sodium bicarbonate then 

 was found : 



Salt taken. 



Loss of salt. 



H 2 0. 



Diff.=C0 2 . 



C0 2 in Res. 



Sum CO : 



1-4265 



36*68) 



10-91 



25-77 







1-5995 



36-81 



10-90 



25-91 







1-3200 



36-71 



10-91 



25-80 



26-25 



52-05 



1-3723 



36-73 



10*98 



25*75 



26-37 



52*12 



1*4296 36-73 10-92 25*B1 26*31 52*09 



Two determinations of total C0 2 gave average of 51*98 per 

 cent; two determinations of alkali gave average of 36*88 per 

 cent lSra 2 equivalent to 26*17 per cent C0 2 . Subtracting 

 26*17 from 26*31, average amount of C0 2 in residue, we have 

 0*14 per cent C0 2 not expelled by heating to sintering. 



Comparing these amounts of excess of C0 2 , retained by the 

 residues of the ignition, with the weight of salt taken we have 

 the following: relations. 



No. of deter- 



Average 



Average 



Relation of 



Sample. minations. 



wt. taken. 



excess. 



excess to weight, 



Urao No. 1 3 



1-0638 



0-09 



0-084 



Urao No. 2 4 



1-1761 



0-09 



0-077 



Bicarbonate 4 



1-4296 



0-14 



0-091 



Average 0*084 



Hence we may say that if sodium bicarbonate, or a salt con- 

 taining a large proportion of it, is heated till it sinters without 

 fusing and is kept at that temperature for one hour, it still 

 retains C0 2 in excess of the amount required to form mono- 



