60 
The water in the lime-mud was estimated by heating to 
110° in a current of hydrogen till a constant weight was 
obtained. Thus 34*6% of water was found, and calculating 
now on dry residue , we get as 
Na 2 C0 3 insoluble, 3*21% 
„ soluble, 4 , 00% 
„ total 7*21 * 
(1) After first washing a weighed quantity of the lime- 
mud, passing C0 2 to convert any lime into carbonate, and 
washing again to remove soluble alkali, the residue was 
ignited for an hour strongly, and then after a thorough wash- 
ing with dilute alcohol, precipitation of any dissolved lime in 
filtrate, determination of soda obtained, and spectroscopic 
examination of residue, we found all soda was thus removed. 
This result agrees with that obtained by ignition of the 
precipitates we prepared. Kynaston found the same many 
years ago, in some examinations of lime-sludge, and hence 
we can quite confirm his results. 
(2) The experiment was now tried of boiling a weighed 
quantity of the mud (having first passed CO a ), for six hours 
continuously with water, from time to time replacing what 
was lost by evaporation. The whole was now filtered and 
washed thoroughly, the filtrate being carefully evaporated 
to dryness. The residue gave a slight soda reaction in the 
flame, and was dissolved in hydrochloric acid, lime and 
other bodies precipitated (a little iron and alumina with 
ammonia, and the calcium as oxalate), and then this filtrate 
was also evaporated to dryness. By this means it was 
found that practically all the soda was extracted by the 
prolonged boiling, the amount left behind being inappreci- 
able. 
It may now be interesting to mention that Fritzsche in 
1864 (Journ. fur Prakt. Chem. 93, 339) succeeded in obtain- 
ing crystals artificially of the body till then only known as 
a mineral under the name of “ Gay-Lusslte” These crys- 
