396 Scientific Intelligence. 



tures would combine to form saturated molecules N 2 2 and 

 N 2 4 , Daccomo and Victor Meyer have submitted these gases 

 to a temperature of -100°. By means of a simple apparatus, 

 nitrogen tetroxide was exposed to a temperature in two ex- 

 periments of — 96° and — lOV and its density was found to be the 

 same as that possessed by it at ordinary temperatures. No evi- 

 dence either of the existence of N 2 2 at these temperatures was 

 obtained ; so that if this compound exists it is completely disso- 

 ciated below this point. The apparatus used consisted of two 

 exactly similar air thermometer bulbs, filled the one with air the 

 other with nitrogen tetroxide. The liquid employed as a seal 

 was sulphuric acid, the level being made exactly the same in both 

 tubes. The bulbs were placed close together and covered with a 

 mixture of solid carbon dioxide and ether. The contraction was 

 exactly the same in both tubes, showing that the tetroxide had 

 not changed its density. — Ber. Berl. Ghem. Ges., xx, 1832, June, 



188V. G. F. B. 



3. On the Behavior of Phosphorus, Arsenic and Antimony at 

 a white heat. — Mensching and Victor Meter have obtained 

 evidence that phosphorus and arsenic suffer a marked loss of 

 vapor density at a red heat and that at a white heat they approxi- 

 mate the values P 2 and As 2 , although the densities corresponding 

 to these molecules have not yet been observed. With regard to 

 antimony, the authors have succeeded in determining its hitherto 

 unknown vapor density, using a porcelain vessel. This element 

 behaves in an entirely different way from phosphorus and arsenic, 

 no molecular weight corresponding to the formula Sb 4 existing. 

 On passing into the state of vapor, which it does with difficulty, 

 it assumes at once a molecular condition represented by a formula 

 smaller than Sb 4 and also than Sb s . So that its actual molecular 

 size is either Sb 2 or Sb l5 but which of these has not yet been de- 

 termined owing to the difficulties of obtaining a normal antimony 

 vapor having an invariable expansion-coefficient at this high tem- 

 perature. — Ber. Berl. Ghem. Ges., xx, 1833, June, 188*7. 



G. E. B. 



4. On a Portable Apparatus for the rapid estimation of Car- 

 bon dioxide in air. — On account of the importance for hygienic 

 purposes, of rapid and accurate determinations of carbon diox- 

 ide in samples of air, Pettersen and Palmquist have devised a 

 portable apparatus for this purpose with which in a few minutes 

 the amount of C0 2 in a specimen of air can be determined to 

 within 0*01 per cent. Referring to the original paper for an illus- 

 tration and description of the apparatus, it may here be stated 

 that each experiment consists of three distinct stages of operation. 

 In the first the air to be examined is drawn into the apparatus, 

 and measured. The cylindrical vessel in which it is contained has 

 a capacity of 18 cc . It terminates below in a graduated scale tube, 

 the lower part of which has a larger diameter than the upper, a 

 mercury reservoir being connected to the lower end by a rubber 

 tube. Above the measuring vessel is connected to a delicate 



