189 
Natural Wistory. — Mineralogy. 
been described as volcanic ; but the circumstance of its contain- 
ing prismatoidal zeolite, proves that it is a Neptunian rock of 
the secondary trap formation. 
S3. Jameson^ s Mineralogy. — Professor Jameson has just pub- 
lished a new edition of his System of Mineralogy, in which mi- 
nerals are arranged according to their external characters, and 
in conformity with the principles of the natural history method. 
Having now a system of mineralogy founded entirely on Ex- 
ternal characters, we shall look anxiously for one according to 
Chemical principles. It does not appear possible to form a con- 
sistent arrangement by employing external and chemical charac- 
ters together. The method used in Professor Jameson’s work, 
which is nearly that of Werner and Mohs, will form a depart- 
ment of the general system of Natural History, along with Bo- 
tany and Zoology ; while the chemical arrangement will fall to 
be considered as a branch of the general system of Chemistry, 
Vitreous Quartzose tubes of the Senner-Heath. — In the 
second volume of the Transactions of the Geological Society of 
London, there is a particular description of vitreous quartzose 
tubes, about an inch and a half in diameter, and which sometimes 
descend 30 feet into the surrounding loose sand. The interior of 
these tubes appears to have been melted, and every circumstance 
of form and situation favours the inference of the member of the 
Society, that they have been produced by lightning. We 
have been lately favoured with a beautiful series of specimens 
of these tubes, collected at Irton by the original discoverer of 
them, E. L. Irton, Esq. of Irtonhall, Cumberland, and find, 
that they are of precisely the same nature as those which have 
been lately discovered in the Senner-heath in Germany. The 
vitreous tubes of the Senner-heath are situated in loose sand, 
have an inconsiderable diameter, but a length of from twenty to 
thirty feet, and their interior is slaggy and vitreous-like. 
25. Geognostical Situation qf Topaz in the mclnlty of Villa 
Rica in Brazil. — The topaz mines are situated in chlorite-slate, 
which appears to rest on a sandstone of the primitive class. 
The topaz is said to occur in regular crystals, or in angular 
masses, or nests of lithomarge, along with rock-crystal. 
26. Mineral riches of the Capitania of Minas Geraes in 
Brazil. — Probabh'- no country in the Avorid affords so much 
