ZOOLOG r AND BOTANY, MICROSCOPY, ETC. 
397 
dealers, collectors, and museums had been supplied, was sold by the 
owners to chemists for the preparation of hydrofluoric acid, or thrown 
away as worthless. A part is said to have come to Paris fifty years ago, 
and to have been used by opticians in lenses and prisms for experiments 
on heat radiation. The remnants presumably of this remarkable find, 
which included some water-clear crystals (cubes) as large as one’s head, 
hidden away in cellars, &c., were purchased by the author in the pre- 
ceding year from the grandchildren of the original fintlers, and were 
thus saved for optical purposes. 
The precise locality of that old find had been forgotten. By means 
of the labels, however, found in the Bern Museum, Herr v. Fellenberg, 
who has assisted the author in these inquiries in the most friendly way, 
was enabled to fix it as the south-west slo2)e of the Oltschihorn, the 
ofislioot of the Schwarzhornstock towards the Lake of Brienz. 
Chance investigations made with the help of some Oberland crystal- 
seekers proved the frequent occurrence of fluor-spar in the neighbour- 
hood, but the old locality was not discovered, nor was further 
material with the characteristics of the earlier find obtained. The firm 
of Carl Zeiss therefore took u|> the quest, and during the summer of 
this and the preceding year caused regular excavations to be made by a 
large number of practised workmen under the direction of an agent. By 
this means, in July 1888, on a steep, almost inaccessible rock about 
1900 metres above sea-level, the hole was discovered out of which came 
the find of 1832. It was found, however, to be practically exhausted. 
Further investigation of the mountain which — belonging to the upper 
Jura— is distinguished by massive schist formations with numerous 
precipices, fissures, and cavities, was then made. In this way semi- 
transparent calc-spar and fluor-spar, crystallized in large cubes, but so 
far as purity was concerned in no way comparable with that found in 
the old locality, were discovered in several places near that spot. Of 
several hundredweight collected, only some pounds were clear and 
suitable for optical purposes. In August of the present year the work 
was therefore discontinued, after all traces found by blasting had been 
followed up as far as they gave any indications of better results. It 
therefore appears beyond all doubt that the single locality which formerly 
afibrded fluor-spar in large clear masses is now completely exhausted. 
The employment of the mineral for Microscope lenses is hardly 
affected by this ; for the comparatively small quantity required for this 
purpose is assured by the general occurrence of less perfect material, 
from which, with some difiiculty, it can be picked out. On the other 
hand, the further extension of its use in optics will be dependent in 
every way on the discovery of new localities which afford large crystals 
or cleavage-masses of similar purity to that which was formerly found 
at Oltschihorn. 
Perhaps this communication may help to make this mineral, so 
valuable to optics, an object of greater attention, and possibly to bring 
to light localities of it which have hitherto remained unnoticed. 
J. M. M. writes,* in reply to a correspondent “ Prismatique,” 
“ ‘ Fluorite ’ is simply the Continental name for common fluor-spar, and, 
* Eiigl. Mooli., li. (18'J0) pj!. 205-h. 
