586 Scientific Intelligence. 



beads are especially striking on account of the white background 

 furnished by the rod. Fusions for the manganese and chromium 

 tests can be made very satisfactorily upon these rods. The rods 

 serve well also in the place of asbestos fibers, for producing sub- 

 limates from the flame upon porcelain. The rods are stuck 

 into a cork for use, and after using the end is broken off, so that 

 beads and fusions may be preserved for reference. The cost of 

 the rods, about l mm thick and 15 cm long, is 1 to 1^ pfennig in 

 Germany, so that there is considerable economy in their use as 

 compared with platinum wire. — Berichte, xlv, 382. h. l. w. 



3. The Combustion of Carbon Monoxide. — The combustion of 

 carbon monoxide has been usually regarded as taking place 

 according to the equation 2CO + 2 = 2C0 2 . This equation does 

 indeed express the final result, but it is known that the reaction 

 is not a direct one, for Dixon has shown that traces of moisture 

 are indispensable for the reaction even at high temperatures, and 

 Remsen has found even at 300° ozone is incapable of oxidizing 

 the gas. However, moist palladium-black, even at ordinary tem- 

 perature, causes carbon monoxide and oxygen to combine. 

 Traube has attempted to explain these facts by assuming an 

 intermediate formation of hydrogen peroxide as follows : 



CO-fH 2 O + a = CO 2 + H 2 O 2 

 CO + H 2 2 = C0 2 + H 2 



Wieland now presents a new view of the matter. He has found 

 that moist palladium-black, in absence of oxygen, causes the oxi- 

 dation of carbon monoxide, apparently according to the equation 

 CO + H 2 = C0 2 +H 2? and he has shown that a first product of 

 the reaction is formic acid : CO -f H 2 = HCOOH. Then, since 

 palladium-black rapidly decomposes formic acid, as is well known, 

 the final result is : 



HCOOH = C0 2 + H 2 (combined with Pd). 



Wieland has been able to show further, that formic acid is pro- 

 duced also in the combustion of carbon monoxide at a high tem- 

 perature, by directing the flame against ice and examining the 

 resulting water. Therefore, it appears that the mechanism of 

 the carbon monoxide combustion under all conditions consists in 

 its combination with water and the splitting off of hydrogen 

 from the resulting formic acid. In the presence of oxygen this 

 hydrogen oxidizes at once to produce water for further reaction, 

 and it is in this combination of hydrogen with oxygen that the 

 traces of hydrogen peroxide observed by Traube are produced. — 

 Berichte, xlv, 679. h. l. w. 



4. The Purity of Commercial Metals. — F. Mylius has made 

 analyses of a number of very pure metals obtained from Kahl- 

 baum. Determinations were made of the metallic impurities by 

 the use of samples of 100 grams or more. In most cases the 

 analysis was facilitated by the fractional crystallization of a large 

 part of the metal in the form of a pure salt which left the impuri- 

 ties in the mother-liquor. The zinc, cadmium, tin and lead each 



