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to the Continent, but have been carried with characteristic 
enthusiasm even as far as the peaks of Arran, and the cliffs and 
elens of our north-western isles. 
** A few years ago he resolved to devote himself to a com- 
prehensive study of the rocks to which the general name of 
basalt had been given. ‘Though abundant chemical analyses 
had been made the ultimate chemical constitution of these 
rocks well known, the mineralogical composition of them still 
remained rather vaguely defined. Men were still specu- 
Jating about the mineralogical nature of that part of basalt 
which is soluble in acid, when Dr. Zirkel set to work to 
collect specimens of basalt from every available locality, 
and to prepare thin transparent sections of them for examina- 
tion with transmitted light under the microscope. The result 
of these investigations appears in the litile volume now before 
us, which is appropriately dedicated to Mr. Sorby. Ina brief 
introduction the author recounts the state of the question when 
he took it up. Having collected and prepared upwards of 
500 sections of basalt from the most varied localities, he 
believes that he has obtained samples of at least the chief 
types of composition and structure among the basalts, and he 
now gives us this first instalment of his labour. 
“That Professor Zirkel is still busy with his researches is 
shown by the paper (second in the list at the end of this 
article) which appeared in a recent part of the ‘ Neues Jahr- 
buch,’ and in which he investigates the peculiarities in the 
minute structure of rock-forming minerals, and also of 
artificially-fused basalt and syenite. 
“Herr Vogelsang is another ardent student of the micro- 
scopic structure of rocks. A few years ago he published a 
little work containing the most beautiful coloured illustrations 
of that structure which have yet appeared. In the present 
paper he describes under the name of crystallites the non- 
crystallised, but yet more or less regularly grouped inorganic 
bodies which are found in crystals and rocks. 
“Professor Fischer’s little pamphlet is a modest produc- 
tion, but one which could not have been prepared without a 
great deal of hard work. Finding that minerals which to all 
outward appearance are simple and homogeneous, can yet be 
resolved by microscopic examination into as many as some- 
times four distinct minerals, he has analysed by this method 
some sixty minerals, and publishes his results in the 
present paper, which should be in the hands of every 
petrographer. 
“ Professor Tschermak’s essay shows how by microscopical 
examination with polarised light it is possible to distinguish 
