242 
The bottles now made at F. Siemen’s works at Dresden, are 
not common black wine or beer bottles, but a superior sort used 
by vintners and druggists; the writer has critically examined 
them, and undoubtedly they are good glass, free from defects 
or blemishes of any kind, and of very light colour; some of 
them had a tinge of orange brown, which owns to a slight 
addition of manganese oxide. Crucible melting pots are not 
employed for glass making in Germany, but the materials for 
glass are melted in large tanks made of refractory clay, and of 
a peculiar domed shape, for the reverberation of the heat 
(1100° C. being the melting point of glass). 
Ill. PORPHYRITE (Italy)— 
Belongs to a family rich in species. This rock is quartzless 
or else poor in that mineral (Quarzfreierorthoklasporphyr of 
the Germans).* The density of these porphyritic rocks amounts 
from 2°63 to 2°76; it consists of a mass of compact felspar 
enclosing as with a paste crystals of Orthoclase, and of Oligo- 
clase or Albite. The external character does not differ from 
that of quartziferous porphyries, except from the absence of 
quartz. The ground mass or paste is easily fusible, and is 
generally of dark colour, more or less porous, approaching in 
tone of colour a dark chocolate brown. Often in addition to 
the felspar, its accessory is some of a deep brown coloured mica, 
or reddish or green mica. In NE. Italy, South of the Tyrol in 
Venetian territory, these rocks are mostly found and are much 
sought for their attractive and striking effect as building stones, 
where richness and esthetic character are desirable to be 
considered. 
This is a burnt porphritic granite which may be mentioned 
as germane to the general subject, inasmuch as whilst staying 
for a few weeks in Venice in the summer of 1887, the author 
availed himself of the opportunity of inspecting the ruined 
interior of the burnt chapel, the Capella del Rosario, which 
formed an adjunct to the ancient Church of 8S. Giovanni e 
* Rosenbusch. Mikros. Physiograph der massigen Gesteine. 2nd edit. 
ii. 427. Stuttgart, 1887. 
