909 
and from Langban in Sweden. On melting them exposed to the air 
as well as in a nitrogen-atmosphere, they always become darker by 
a decomposition, and by a slight oxydation. However, this seems 
to have .no appreciable influence on the meltingpoint, but only 
makes the localisation of the heat-effects on the curves more trouble- 
some. In all cases we found on these curves three successive 
heat-effects, which however, on repeated melting of the mass were 
gradually effaced, a more detailed research must bring a full decision 
as regards the true significance of these successive effects. The 
measurements were made with thermoelement Il; the results, after 
correction, are reviewed in the following table: 
Natural Rhodonites. | 
| Artificial | From i ia el 
| Rhodonite Radau-Tal | pom Frank- | 
sil From | 
| lin, N. J.) karen es Longbin 2) 
Effect: 
MV. °C.|MV. eC|MV. °C] MV. °G/MV. oc 
| in air 
ZT | 12820 1274° | 12620 1257° | 12185 1221° | 12800 12729 | 12740 1267 | 
2 | 12024 1208 — — [11410 1156 | — — — — 
3 | 10920 1115 — — — — — — — — 
| in | | 
nitrogen | 
Z| 12810) 12139 12535 12599 | 12175 12209 | 12734 12679 | 12710 12659 | 
| 11500 1164 12000 1206 — — | 
r | 12800 12729 | 12710 _ 12700 | 
2 | 12020 1207 — — — — | == = 
3 | 11180 1137 | | | | 
| 
| \ 
In cooling-experiments undercooling of 10 or 40 M.V. below the 
maximum crystallisation-temperatures immediately following, appeared 
1) The rhodonite from these places is analysed by Pirsson; he determined : 
SiO, : 46,1%; MnO: 34,3°/9; FeO : 3,69/9; ZnO: 7,3°/o ; CaO: 7,09/, ; MgO: 1,3°/. 
2) According to an analysis of Linpsrrém the rhodonite of Langban contains: 
Si0,: 47,7%; MnO: 31,60; FeO: 0,5%; CaO: 18,29; MgO: 1,2%. The 
Swedish rhodonites seem to contain no ZnO or only traces of it. 
