124 On the Chemical Composition of Wernerite, 
have now a sufficient knowledge—such an assemblage as the 
Trilobites described to us in the work of Barrande, or the 
Brachiopoda as exhibited in the monograph by Davidson ; to 
take and analyse the ample lists of extinct beings marshalled 
in the pages of Morris, or in the more general muster-rolls of 
Bronn and Alcide d’Orbigny ; and then, having done this, to 
consider earnestly and fairly the idea that I have ventured to 
suggest of the manifestation of Polarity in Time. 
On the Chemical Composition of Wernerite, and the 
Products of its Transmutation. 
The minerals included under this name have recently been 
made the subject of an investigation, conducted in Rammels- 
berg’s laboratory, by Gerhardt von Rath.* His object was to 
remove, as far as possible, the uncertainty which obtained 
with regard to the normal chemical composition of these 
minerals, and likewise to ascertain in what manner that 
composition is altered. 3 
For the solution of the former question minerals were 
selected for analysis whose physical characters bore testi- 
mony to the conservation of their original nature. Decisive 
indications as to the latter question could only be obtained 
by the analysis of Wernerite which had evidently suffered 
transmutation. Those products of this process which dif- 
fered most in chemical composition from the original mineral 
appeared best suited for this purpose, because analysis of 
them would make the nature of the change more clearly 
evident, and the possibility of its being concealed by the 
errors of analysis or the uncertainty as to the normal com- 
position would be much lessened. For this reason definite 
individual mineral substances—mica, epidote—were selected 
for analysis, as well as substances which have neither a defi- 
nite composition nor a distinctive form. All the substances 
analysed for this purpose presented the most unquestionable | 
ne a ——$______ 
——— ee 
* Annalen der Physik und Chemie, 1853, September and October. 
