380 Reviews. [ April, 
questions which ordinary chemical processes are unable to unriddle. 
What, for example, constitutes the blue part of the flame cf a candle ? 
The spectroscope answers, vapour of carbon. The author once thought 
that the blue was caused by light carburetted-hydrogen, since he 
observed the same spectrum from the flame of this gas, and also from 
that of the base of a candle flame. A perusal of Dr. Attfield’s paper 
on the “ Spectrum of Carbon,” however, induced him to reconsider the 
subject, and to examine the spectra of numerous other carbon com- 
pounds. In all these he observed the same spectrum, which, being 
common to everyone, must have been derived from the common con- 
stituent, carbon. The means which the author employed, and the 
appearances he observed, are well described in this tract; and any 
experimenters working in the same direction would do well to con- 
sult it. 
CuemicaAL FormMuLz. 
Dr. Opiine has published* a set of tables of chemical formule, which 
we venture to say will prove as useful to teachers as to students of 
chemistry. He adopts an original mode of classifying the elements 
which is, perhaps, as reasonable as any other yet proposed, or possible, 
in the present state of our knowledge of these bodies. 
The formule are all constructed on the unitary system of notation, 
and in the absence of a complete work of chemistry based on that system, 
these tables will prove of great assistance to students, who are obliged to 
read a book written upon the old system, and listen to a lecturer who 
teaches upon the new. 
Lecturers who are beginning to teach the unitary system, will find 
in the tables the materials of a very useful set of diagrams. 
* «Tables of Chemical Formule,’ arranged by W. Odling, M.B., F.R.S, &c., &e. 
London: Taylor and Francis, 1864. 
