Right Rhombic Baryto-Calcite. 47 



The flask was corked, the alcohol was heated to the boiling 

 point, and then left to digest for some hours on the salt. It 

 was then drawn off by a sucker, an additional portion of the 

 same alcohol was poured on the undissolved salt, and the di- 

 gestion continued as before. A third portion of the same al- 

 cohol was finally added and the whole was thrown upon a 

 filter to collect the undissolved nitrate of barytes. After being 

 dried in a heat of 300° this nitrate weighed 1 2*05 grains, equi- 

 valent to 9*08 grains of carbonate of barytes. 



4. All the alcoholic liquids were collected together in a small 

 retort, and the alcohol distilled off till only a few drops of 

 liquid remained in the retort. It was taken out of the retort, 

 evaporated to dryness, and digested again in alcohol of 0*800. 

 The whole dissolved with the exception of a dirty yellowish 

 black powder, which was separated, and weighed after ignition 

 0*3 grain. When examined before the blowpipe it proved 

 to be oxide of manganese, not quite free from iron. 



5. The alcoholic solution was distilled as before. It was 

 then evaporated to dryness, and the salt that remained heated 

 in a platinum crucible till the nitric acid was decomposed. 

 The residue was digested in weak nitric acid and the undis- 

 solved portion collected on a filter, ignited, and weighed. It 

 amounted to 0*67 grain, and was red oxide of manganese, not 

 quite free from iron. This with the preceding 0*3 grain makes 

 0*97 red oxide of manganese, equivalent to 1*45 grain of car- 

 bonate of manganese. 



In my first analysis I separated the manganese by caustic 

 ammonia, but I could not in this way free the nitrate of lime 

 from all traces of manganese. In the second analysis I em- 

 ployed with the same object sulphohydrate of ammonia ; but 

 this method only succeeded imperfectly. Even the process 

 employed in the third analysis did not render the lime quite 

 colourless, though the manganese and iron remaining were 

 very small in quantity. 



6. The nitrate of lime was converted into sulphate, ignited 

 and weighed. 



The results of the analysis are 



Carbonate of barytes 9*58 or 60*63 



Carbonate of lime 4*77 or 30*19 



Carbonate of manganese 1*45 or 9*18 



15*80 100*00 

 These numbers are equivalent to 



3*92 atoms carbonate of barytes, 

 3*83 atoms carbonate of lime, 



1 atom carbonate of manganese, with a little carbonate 

 of iron. 



