THE BEGINNINGS OF PHOTOGRAPHY. S37 



at Meissen, and was the author of several philological, historical, 

 and poetical works (F. All)inus, Meissniche Land-('hronica, p. 322). 

 His treatise on metals, referred to, is not in the least alchemistic. Son 

 of a goldsmith, born and living in the mining disti-icts in Saxony, it 

 is natural that he should have taken an interest in metals. So far as I 

 have l)een able to gather, the accounts of his observations of the action 

 of light on horn silver, or silver chloride, are quite apocrA^phal. 



In G. D. Schreber's Life of Fabricius (1717) we find several pas- 

 sages showing the friendship that existed ])etween Fabricius and Agri- 

 cola and the help given to the latter by the former in compiling his 

 book, to whicli the notes by Fabricius were intended as a supplement 

 and were so pu])lished in the edition of 1565. 



In another treatise in the same volume, b}" Johann Kentmann, 

 describing the minerals of Misnia (Meissen) there is a list of 84 difi'er- 

 ent ores of silver, and among the yellow ones he describes one as 

 "pellucid like horn, from Marienberg: melts over a candle." 



The only distinct early notice of horn silver and of its change of 

 color I have come across is in a little German book l)y H. Modestin 

 Fachs, mint master at Leipzig, Probier Buchlein (1567). At page 184, 

 in a list of silver ores, he mentions horn silver ore (Horen Silberertz) 

 and says: "' It looks just like horn, such as is used for horse combs, 

 and may ))e cut and impressed like wax; is ver}' rich in silver. Like 

 it, such horn silver is wont also to change to the color of oxidized lead 

 (bley nichter.) " 



Johann Mathesius, in his Bergpostilla, or Sarepta (1578), mentions 

 horn-colored silver ore as lateh' found in the Marienberg mines, trans- 

 parent like the horn of a lantern and fusible over a flame. (This maj'' 

 explain why Agricola does not notice it.) He does no(f note the 

 change of color on exposure, but in the Meissnische Berg-Chronica 

 (1590), page 110, Petrus Albinus describes a remarkable white semi- 

 fluid silver ore from St. Georgen, which was said to be like butter- 

 milk when found, but soon hardened in the air, becoming like sand or 

 grit, and its white color changed to l)rown or rusty. This semiHuid 

 ore is also noticed by Albertus INIagnus and Agricola, ])ut there is 

 nothing to show it was a chloride. Albinus also mentions horn silver 

 from Marienberg (p. 127) in nuich the same terms as Mathesius, and, 

 with I'c^gard to the variety of colors it assumes, he quotes the extracts 

 from Fabricius, given above, as referring to this ore. In this way the 

 earl}' knowledge of native horn silver and its liabilit}^ to change of 

 color seems to have been entirely conlined to iho mining districts of 

 Saxony. 



Even in the great work of Aldrovandus, Musajum Metallicum (161S), 

 although we tind a very full and interesting account of silver and its 

 ores, with many illustrations, nothing definite is said about horn sil- 

 ver. Nor does Father Kircher mention it in his Muudus Subterraneus 

 (1665). 



