80 DRS. SCHUSTER AND ROSCOE ON 



We also find that the philosopher's stone is often called 

 " the red tincture/' from tinguo (to moisten) . 



It appears therefore very probable that the name of our 

 science is derived from ^u/ao?; and the proper spelling 

 would therefore be Chymistry, as the ' Times ' newspaper 

 for a long time insisted. As, however, this derivation 

 has not yet been proved quite satisfactorily, the time- 

 honoured term Chemistry will remain in use, and, I think, 

 be retained even if it should be shown that ^^u/^eta was tlie 

 original spelling. 



X. Note on the Identity of the Spectra obtained from the 

 different Allotropic Forms of Carbon. By Arthur 

 Schuster, Ph.D., F.R.S., and H. E. Roscoe, LL.D., 

 F.R.S. 



Read December 2ncl, 1 879. 



Spectrum analysis serves as our most delicate test of the 

 chemical constituents of a substance. Hence it appeared 

 not uninteresting carefully to examine the nature of the 

 spectra obtained by the combustion of natural graphite 

 and of diamond in a vacuum of pure oxygen, and to 

 compare the spectra thus obtained with the well-known 

 spectrum of carbonic oxide obtained from charcoal. The 

 preparation of such an oxygen-vacuum which shall yield 

 an oxygen spectrum exhibiting no other lines than those 

 of oxygen is a matter of considerable difficulty. The 

 slightest trace of any impurity containing carbon produces 

 the spectrum of carbonic oxide. For this reason the use 

 of caoutchouc tubing and of greased stopcocks must 

 altogether be avoided, and thus the experimental diffi- 

 culties are considerably enhanced. 



