1946 I PropriBt6s extensives et grandeurs molaires partielles par W. MUND, 1. FRlPlAT et E. SALLETS (Louvoin) INTROUUCTION Consid6rons, ;omme le plus souvent dans la suite, des systhmes dont la temphrature, la pression et la composition chimique sont B chaque instant uniformes. Cette absence per-La constante a se determine facilement en additionnant membre h mernbre lea Bquations Bquivalentes aux prBc6dentes de e,n dX, X I dX, X, ' d e P ,n ct -=--On obtient e,X, f e , X ,n (XI + &) x,s, O =Mais, en vertu de (9), ezXz+e,X,=e, alors que X l + X , = l . PROPRI~ETES EXTENSIVESPar consequent a = c et 1 'on peut Ccrire tle

In view of the similarity (7) between photochemical and radiochemical reactions it was decided to make an absorption spectral analysis of acetylene polymerizing under the influence of radon. This method has already been applied to the corresponding photochemical reaction by Kato (4), Kemula and Mrazek (6), and Livingston and Schiflett (10), who detected the presence of benzene (4, 6, 10) and naphthalene (6) in the polymerizing gas in addition to the solid cuprene-like polymer reported by various authors (2, 1, 15, 9, 16). The ultra-violet absorption spectrum of benzene (3) is exceedingly distinct and well established, and its presence during the course SUMMARY Absorption spectra of acetylene polymerizing under the influence of radon were photographed. By this means the formation of benzene was demonstrated for both the alpha-ray and the beta-gamma ray reactions. That cuprene is not the only polymer produced in appreciable quantities was shown by freezing out in a carbon dioxide-acetone mixture a solid which proved to be a volatile liquid at room temperature. This liquid was chiefly benzene. It appears as a result of a reaction proceeding simultaneously with cuprene formation.

Etude cin6tique compl6mentaire de la &action provoqu6e par les particules alpha Hz 3. Dz = 2 H D , par W. MUND et M. VAN MEERSCHE (Louvain)

IntroductionL'action des rayons alpha sur un niClitnge t~c~ui~iioli.c~ir h i r v de H, et de D, a @t6 @iudi&e en 1940 par Mund, hlaertkenicyi.. Van 'ripgelen ('1 . Les prdsentes rrcherches, c n f r c prises dans le but d'am6liorer la pi'6cision espCrimentiile et t i c > reviser la cinPtique yui avaii. pu Ctre dtahlie pr~visoirenret~~, ne rnotlifient guEre les conclusions de ce ~m:niier travail, q r i ; t i i t a l'cxistcitic-c r r i h c~ de 1;i rBilctio11, la 1vmd)ilitB de 1;i sriivre piiv une methodc condnctiin@f.riyur et 1;i iiCcwsit6 dr l'interprt:tc*r par UIL par un tube B P20,. Le ballon R , d'une capacite dc . 5 litres, P l a n t immerg6 dam la glace fondante, on y admettait le I), jusqu'g la prcssion P, et ensuite cle l'hydrogbne jusqu'h la pres-I', sion P. Le rapport des pressions ___-i'ti3it dklermini. l>iir P -P, Ic rksultat, d'une mesure de densit6 e f f e c k e sur 1111 6ch:intil- contenue dans un m6lange des melanges m,, et nil. Supposons, par exemple, que le gaz fourrii par u i i premier prf.l&venierit en V, exerce dans le volume e + n une pression p1 qu'on mesure tl';hord. On ferme alors r,, ouvre pendant un court ins- Van Pee el

Having found in previous work1 that acetylene gas when mixed with radon is slowly converted into a pale yellow powder, we investigated further2 by a simple method the rate of such polymerization. The quantitative results were worked out:1.Knowing the number of a particles emitted by a given quantity of radon with equilibrium amounts of RaA and RaC (i curie gives 3 X 1.772 X 16 (1-e~xt) particles. 2.Taking into account the partial absorption of the a particles by the walls, RaA and RaC being wholly deposited.The formula we used3 rested upon the validity of Geiger's ionization law. We calculated thus that, at o°C and at a pressure of about 70 cm. of mercury, every a particle emitted by radon (range 3.94 cms.) brings about the condensation of 4.38 X io6 gaseous molecules. The total ionization along the path of an a particle in acetylene being 2.13 X io5, it follows that for each ion, 20.5 molecules fall out.As S. C. Lind4 first suggested, the ratio M/N is often near unity, M being the number of reacting molecules and N the number of ions produced. This led M. Bodenstein6 to correlate the radiochemical reactions which follow the rule with his primary photochemical reactions. In the case of acetylene, hotvever, the M/N ratio is much larger than in most other primary reactions, though much smaller, indeed, than in the HC1 synthesis, which Bodenstein compares with a photochemical secondary reaction. Thus arose the question to which class the acetylene polymerization would belong from other points of view, namely, as regards the influence of oxygen, pressure and temperature.