104 COMBUSTIBLE ACIDS. 



4. x ne oxalate of lime dried at 95 lost 



lime. 



grains of its weight when kept in the tempera- 

 ture of 560 ; and, as the salt continued still 

 neutral, this loss must have been owing to the 



3. 9 grains of oxalic acid crystals were dissolved in water, and 6 -75 grains 

 of anhydrous carbonate of soda were thrown into the solution : an efferves- 

 cence took place, and the carbonate gradually diminished in bulk ; but the 

 liquid soon became muddy, and the whole carbonate never disappeared 

 though the effervescence completely stopped. I, therefore, evaporated the 

 liquid to dryness in a gentle heat, and pouring water upon the dry salt, di- 

 gested it for a considerable time on the sand bath. At first the liquid red- 

 dened vegetable blues strongly ; but the property became gradually wjeaker 

 and weaker, and after 48 hours' digestion I found the liquid perfectly neu- 

 tral. From this experiment it appears, that 9 grains of oxalic acid crystals 

 just saturate 4< grains of soda, which is the quantity of that alkali contained 

 in 6-75 grains of anhydrous carbonate. 



4. I mixed together solutions of oxalic acid crystals and anhydrous car- 

 bonate of potash, in the proportion of 9 grains of the former to 8-75 grains 

 of the latter. This solution, by evaporation, yielded crystals of oxalate of 

 ammonia to the very last drop ; these crystals were neutral, and had the 

 shape and properties of oxalate of potash. 



5. 9 grains of the crystals of oxalic acid were dissolved in water, saturated 

 with ammonia, and the solution heated till every trace of ammonia in ex- 

 cess had disappeared. 23-625 grains of crystals of acetate of lead were 

 then dissolved in water with the assistance of heat, and the two solutions 

 were mixed together : the oxalate of lead, which was formed, subsided to 

 the bottom very fast, in consequence of its great weight, and left the super- 

 natant liquid quite transparent and colourless. This liquid was tested with 

 muriate of lime and sulphate of soda, but was not in the least altered by 

 either ; showing that it contained no sensible quantity either of oxalic acid 

 or oxide of lead. Now, 23-625 grains of acetate of lead contain just 14< 

 grains of oxide of lead, which is equivalent to an atom. From this experi- 

 ment, like the former, it follows, that 9 grains of oxalic acid crystals con- 

 tain just the equivalent for an atom of anhydrous acid. 



6. The preceding experiment was repeated, with this difference, that 

 8-875 grains of crystallized oxalate of ammonia were substituted for the 9 

 grains of oxalic acid crystals : the result was the same the residual liquid 

 contained no oxalic acid or oxide of lead. This is the counterpart of the 

 second experiment, and shows, as it did, that 9 grains of oxalic acid and 



