64 



T. JL Chotard—Cfrao. 





No. 1. 



No. 2. 



No. 5. 



No. 6. 



No. 7. 



No. 9 



NaHCO s grms.._ 



10-5 



21-0 



10-5 



l'J-5 



42-0 



5-25 



Na.,C0 3 " -- 



53-0 



53-0 



53-0 



53-0 



53-0 



3-50 



NaCl " .. 



29-25 



29-25 



14-62 



58-5 



58-5 



29-25 



The first products obtained from the solutions by spontaneous 

 evaporation had the following compositions : 



No. 1, 1st. No. 2, 1st. No. 5. 1st. No. 6, 1st. No. 7, 1st. No. 9, 2d. 





Acicular. 



Scales. 



Acicular. 



Acicular. 



Scales. 



Acicular 

 matted. 



H o 0.... 



19-58 



11 -7S 



19-54 



19-42 



11-63 



18-91 



C0 2 ._.. 



38-73 



51-69 



37-88 



37-76 



51-52 



36-46 



Na 2 0.__ 



40-07 



36-54 



41-02 



39-85 



36-49 



39-32 



NaCl... 



1-46 



•51 



1-72 



2-88 

 99-91 



undet. 



5-58 





99-84 



100-52 



100-16 



99-64 



100-27 



Hypothetical Composition. 



H 2 0_-_- 



15-37 



1-25 



15-96 15 



"55 



•92 



15-41 



Na 2 CO s _ 



.43-69 



•42 



49-00 45 



29 



•64 



46-60 



NaHCO s 



39-32 



98-34 



33-48 36-19 



98-08 



32-68 



NaCl... 



1-46 



•51 

 100-52 1 



1-72 2 



88 



undet. 



5-58 





99-84 



00-16 99-91 



99-64 100-27 







Urao. 



NaHCOs N 



i 2 C0 s ,H 2 H,0 



NaCl 



No. 1 corresponds to 93-15 + 



4-70 + 







•53 + 



1-46 



No. 2 



a 



" -89 + 



98-01 + 







1-11 + 



•51 



No. 5 



u 



" 90-08+ 



.-..+ 



7-89 



■47 + 



1-72 



No. 6 



a 



' 96-56+ 



•30 + 







•17+ 



2-88 



No. 7 



a < 



' 1-374- 



97'57 + 







•70 + 



undet 



No. 9 



u 



< 87-92 + 



....+ 



6-27 



•50+ 



5-58 



A solution made up in the proportions of No. 6 would seem 

 to be best for the production of this salt as the crystallizations 

 were much finer than in any of the others. If the proportion 

 of NaHC0 3 is increased, the excess separates before the urao 

 is formed, while if it is reduced the urao contains monohydrated 

 carbonate. The presence of NaCl is not absolutely necessary, 

 for experiment has shown that a very good crystallization of 

 urao can be obtained without its aid, and even a solution of 

 chemically pure Na 2 CO a , if exposed to the air for some time so 

 that it can absorb C0 2 , will yield crystals of the double salt. 

 It is therefore somewhat remarkable that this salt which seems 

 to be the natural form of sodium carbonate, should receive no 

 notice in the most extensive treatises on the sodium salts or, if 

 mentioned, be confounded with another which, so far as my 

 own observations extend, does not exist at all. 



