REPORT OF CHEMIST. 1993 
oxidation with nitric acid, and the whole loss reported as organic and 
volatile matter. 
LIMESTONES. 
No departure from the usual method was made—the method being 
to dissolve one gramme of the sample in hydrochloric acid, evaporate 
dry, add acid and filter from the insoluble portion; the insoluble por- 
tion was then fused with a little sodic carbonate, and treated as in case 
of iron ores. | 
The solution, free from silica, was first precipitated by ammonia to 
separate iron and alumina, which were usually weighed together; in 
some cases the iron was determined also by reducing a portion of the 
solution and titriring. 
The filtrate from the iron and alumina was precipitated hot by a 
solution of ammonia oxalate, allowed to settle, filtered and washed. 
The precipitate of calcic oxalate was either weighed as carbonate or as 
sulphate. The heating by which it is made into carbonate has to be 
very carefully managed; it was accomplished on a sort of sand bath, 
made by putting some clean washed sea sand into a large (60 ¢. c.) 
platinum crucible, and then heating over a regulated Bunsen burner 
until it was just red hot; into this large crucible could be set the 
small ones holding the oxalate, which was thus rapidly and safely con- 
verted to carbonate without the tedious process of heating “ by hand.” 
When a number of ignitions were to be made, this was found to be 
economical of time. All the weighed precipitates were duly tested for 
caustic lime. 
Where magnesia was present in at all large quantities, the original 
calcic oxalate precipitate was redissolved in a little hot hydrochloric 
acid, diluted with water and reprecipitated with ammonia and a fresh 
portion of ammonia oxalate, to recover the small quantity of magnesia 
taken down with the first precipitate. The ammoniacal filtrate from the 
lime was then precipitated with excess of hydrodisodic phosphate. 
Where the lime was determined as sulphate, the oxalate was treated 
in the crucible with slight excess of strong sulphuric acid, heated care- 
fully till dry, ignited and weighed. 
For all precipitates adopted to its use, the “Gooch” perforated 
crucible and asbestos filter was used; the following arrangement was 
found very convenient for the exhausting vessel: upon a sheet of heavy 
