/ 
Chemistry and Physics. 501 
the gas can be passed in is almost unlimited. As the amount of 
tetrachloride increases in the tube, it is necessary to raise the 
delivery-tube to avoid too great a pressure. The liquid is finally 
poured off and distilled, no purification on account of dissolved 
chlorine being necessary.—Zeitschr. fiir Anorgan. Chem., ix, 365; 
x, 47. H. L. W. 
5. Argon and Helium.—Bovcuarp has collected gases ema- 
nating from certain sulphur springs in the Pyrenees Mountains 
and has found that these consist chiefly of nitrogen, with both 
argon and helium. Troosr and Ovuvrarp, working with the 
argon and helium just mentioned, claim that the spectrum line; 
of both these elements disappear when a magnesium wire is very 
strongly heated by electricity in contact with the gases in a 
Plicker tube. The authors assume that argon and helium are 
capable of combining with magnesium at very high temperatures, 
and they state that platinum gives in argon phenomena of volatili- 
zation and combination analogous to those presented by magne- 
sium. ‘These conclusions evidently conflict with previous obser- 
vations upon these new elements.— Compt. Rend., cxxi, 392 and 
394, H. ia. W 
6. Photography of Colors by the indirect method.—A. and K. 
Lumi&ReE take three negatives through orange, green, and violet 
ray filters. To obtain a positive they employ a film on glass 
which contains ammonium bichromate and bromide of silver. 
The negative is printed upon this, and the subsequent washing 
develops a transparent, hardly percepible image, which only 
through color is strengthened to the requisite depth. This first 
image is flowed with collodion, which is sensitized in the same 
manner as the glass, and is exposed to the second negative, and, 
in the same manner, to the third. Repeated layers can be used 
to strengthen the one or the other color until the required effect 
is obtained.— Comptes Rendus, cxx, pp. 875-876, 1895. Jick. 
7. Spectrum of Carbon of the electric oven.—Moissan has shown 
that the carbon in an electric oven through which powerful elec- 
tric currents have flowed is free from foreign admixtures. Dkrs- 
LANDRES has confirmed this and finds only a trace of calcium 
present. The self-purification comes from a species of distillation 
of the volatile impurities. The purest carbon is found at the 
negative pole. The following spectrum is obtained between A = 
480 and A = 220. 
Intensity. A. Intensity. A. 
8 426°70 8 283°64 
5 392°17 4 274°75 
4 391°97 8 264°12 
2 316°83 be 8 251°15 
1 316°57 § 8 250°79 
2 299°34 10 247°88 
1 296°77 8 229°70 
8 283°75 
— Comptes Rendus, cxx, pp. 1259-1260, 1895. J. 7. 
