198 Washington — Kaersiitite from Linosa and Greenland. 



presence of tin, as reported by Lorenzen, is very doubtful and 

 certainly cannot be considered as characteristic of the mineral, 

 as suggested by him. 



Lorenzen's original analysis and the new one are given 

 below, the last two columns showing the figures of the latter 

 as corrected for the 0*77 per cent of apatite present and recal- 

 culated to 100 per cent, and the molecular ratios. 



SiO 





I 



41-38 



II 



39-30 



10-25 



none 



11-16 



1-21 



8-76 



0-06 



none 



1324 



11-29 



2-93 



1-06 



059 



0-32 



III 



39-52 



10-31 



none 



11-22 



1-22 



8-81 



0-06 



none 



13-31 



10-93 



2-95 



107 



0-59 



IV 

 •659 



TiO 





6-75 



•129 



SnO, 



Al 





0-26 



14-41 



•110 



Fe 0„ 





none 



•008 



FeO 



MnO 



NiO 



MgO „. 



CaO ._ 



Na 2 



KO _. 





11-28 

 n. d. 



n. d. 

 13-51 



12-97 



n. d. 

 n. d. 



•122 

 •001 



•333 

 •195 



•048 

 •011 



HO 





n. d. 



•033 



PO 





n. d. 





2 5 



by 

 by 

 II i 



v ra 







I. Analysis 

 II. Analysis 



III. Analysis 



IV. Molecula 



100-56 100-17 



J. Lorenzen, Medd. Gr 

 H. S. Washington, 

 corrected for apatite, 

 tios of III. 



100-00 

 oenl., vii, p. 



30, 1884. 



There is every reason for the belief that the material anal- 

 yzed by Lorenzen was essentially identical with that investigated 

 by us, as is also indicated by the agreement in the figures for 

 Si0 2 , total iron as FeO, MgO, and CaO, so that the differences 

 between the analyses cannot be ascribed to varying chemical 

 composition. Lorenzen's analysis is seriously defective in the 

 assumption that all the iron is present in the ferrous state, as 

 well as in the non-determination of soda, potash, and water. The 

 last is here of comparatively small moment, but the new 

 analysis shows that about four per cent of alkalies are present, 

 and it is well known that all the basaltic hornblendes and 

 others similar to this contain very notable amounts of soda, 

 with often considerable potash, which cannot be ascribed to 

 inclusions. Lorenzen's figure for Ti0 2 is lower than ours by 

 about 3'5 per cent, while his alumina is higher by about the 

 same amount. As our figure for titanium was determined by 

 the colorimetric method, which is capable of a high degree of 

 accuracy, and is the mean of three closely agreeing determina- 





