456 



PROFESSOR W. DITTMAR ON THE BEHAVIOUR OF THE 



which gave 377 mgrm. of C0 2 = 39"18 per cent, and 132*8 mgrm. of Na 2 SO 4 :=60-31 per 

 cent, of Na 2 0, leaving 0*52 for water, or : — 



Na 2 as carbonate, 



C0 2 , 



H. 2 as NaOH, 



Na 2 as NaOH, . 



Other Na 2 0, by difference, 



55-3} 



39-2 J 



0-51 



1-8 J 



3-2 



94-5 



2-3 

 32 



100-0 100-0 



a very singular result, to which, however, as it was obtained by only one analysis of a very 

 small quantity of substance, we must not attach too much importance. 



Thinking, rightly or wrongly, that the great loss of matter observed in this last 

 experiment was owing more to the creeping-out than to volatilisation of caustic alkali, I 

 endeavoured in the following experiments, Nos. 3 to 6, to prevent this by mixing the 

 carbonate of soda operated upon with spongy platinum as explained above. This 

 involved a slight modification in the method of analysis, consisting in this that the weight 

 of substance analysed had to be determined indirectly, namely, by weighing the platinum 

 cornet as it came out of the crucible (within a glass-stoppered wide test-tube), and again 

 after expulsion of the carbonic acid and the complete removal of the soda-salt by 

 exhaustive lixiviation with water. The spongy platinum was found to stick together and 

 to the cornet, so that these operations offered no difficulty, although the washing process 

 proved rather tedious. Experiment No. 3 was a mere rehearsal, to show the practicability 

 of the method ; the results of Nos. 4, 5 and 6 are given in the following table : — 



(4) 



(5) 



(6) 



Time of heating over — 





(a) A Bunsen, 



18 hours 



(b) The blowpipe, . 



1 hour 



Dry Na 2 C0 3 used, . 



34784 



Product in cornet at the end, 





as analysed, . 



2-430 



Weight of C0 2 found, 



0-8826 



Na 2 S0 4 obtained, 



3-3908 



s by Calculation in Percentages — 



Carbonic acid, 



36-321 



Soda, Na 2 0, .... 



60-960 



Water, by difference, 



2-719 



Bunsen not used 



in 5 and 6. 



2 hours 



4 hours 



1-0342 



1-0068 grm 



0-8264 



04482 



0-2991 



0-1480 



1-1415 



0-6376 



36193 



33-021 



60-348 



62152 



3-459 



4-827 



100-000 100-000 100-000 



Assuming that the carbonic acid found is present as Na 2 C0 3 , and that the remaining 

 soda and the water are united, as far as possible, into NaOH, the numbers, as they stand, 

 would show that product No. (4) contains a small quantity of Na 2 0, uncombined with 

 water, while (5) and (6) contain slight excesses of water. The anhydrous soda in No. (4), 

 however, amounts to only about 0'3 per cent., and a very slight correction of the numbers 



