SCIENCE. 
105 
The carbon tetrachloride was prepared by Dr. Hodgkin- 
son, who very kindly supplied me with sufficient for my ex- 
periments. 
On passing the spark without the j*.r in this tube, the 
spectrum observed consists of those sets of flutings which, 
according to Messrs. Liveing and Dewar, are due. to hydro- 
carbon, and the set of flutings which is reversed in the sun, 
and ascribed by Messrs. Liveing and Dewar to cyanogen, 
also appears in a photograph of the violet end of the spec- 
trum, Fig. 2. On connecting a Leyden jar with the coil and 
then passing the spark the flutings almost entirely vanish 
and the line spectra of chlorine and carbon take the place of 
the flutings without either a line of hydrogen or a line of 
nitrogen being visible. 
As a long experience has taught me that these tubes often 
leak slightly at the platinums after they are detached from 
the pump, so that the evidence of such a pibce justificatip is 
only good for a short time, I took the occasion afforded by 
principal double line in the green being seen. The hydrogen 
line Ha(C) was faintly visible when I first observed the 
spectrum, but it got gradually weaker and finally disappear 
ed altogether. When this line was no longer visible the con 
denser was taken out of circuit again, and the same carbon 
bands were seen as before. These bands, therefore, show 
themselves with great brilliancy when a strong and powerful 
spark does not reveal the presence either of hydrogen or 
nitrogen. (Signed) Arthur Schuster.” 
“March 21, 1880.” 
This result, which entirely endorses the work of Attfield 
and Watts, has been controlled by many other experiments. 
I have also repeated Morren’s experiment and confirm it 
and I have also found that the undoubted spectrum of cyan- 
ogen is visible neither in the electric arc nor in the surround- 
ing flame. 
Hence then in the case of carbon, as in the prior cases 
of hydrogen, nitrogen and the like, those who hold that 
a visit of Dr. Schuster to my laboratory while the experi- 
ments wese being made to get my observations confirmed. 
He has been good enough to write me the following letter 
and to allow me to give it here : — 
“ March 21. 
“ My Dear Lockyer. — The following is an account of 
the experiment which I saw performed in your laboratory on 
Monday, March 15 : 
“ A tube containing carbon-tetrachloride was attached to 
the Sprengel pump. As exhaustion proceeded the air was 
gradually displaced by the vapor of the tetrachloride. The 
electrodes were a few millimetres apart. If the spark was 
the flutings are due to impurities must, it would seem, 
abandon their position ; for the flutings are undoubtedly 
produced by carbon vapor. Nor is this all ; the sugges- 
tion that the various difficulties which have always been 
acknowledged to attend observations of this substance may 
in all probability be due to the fact that the sets of carbon 
flutings represent different molecular groupings of carbon, 
in addition to that or those which give us the line spectrum, 
and that the tension of the current used now brings one set 
of flutings into prominence and now another, seems also 
justified by the facts. This suggests the view that a body 
may have a fluted spectrum of compound origin as well as 
taken without a condenser in the vapour the well-known 
carbon bands first observed by Swan in the spectrum of 
a candle were seen with great brilliancy ; I also saw the 
blue band which you said was identical in position with 
one of the blue bands seen in the flame of cyanogen or 
in the spectrum of the electric arc. When the condenser 
and air-break were introduced this spectrum gave way to a 
line spectrum in which I could recognize the lines of chlo- 
rine. The lines of nitrogen were absent, not a trace of the 
a line spectrum. 
This conclusion is greatly strengthened by the preliminary 
discussion of a considerable number of photographs of the 
spectra of various carbon compounds. 
A general comparison of the photographs first enables 
us to isolate the lines in the blue and ultra-violet portions 
of the spectrum (wave lengths 4300-3800) of the substance 
associated with the carbon in each case. 
In this manner the lines seen in the photographs of the 
