58 



SCIENCE 



[Vol. LVI, No. 1437 



iodo-arsine, 4-metlioxy-benzoplienoiie-i'-ditiromo- 

 arsine, 4-methoxy-benzophenone-4'-diiodo-arsine, 

 and 4-niethosy-benzophenone-4'-arsinic (aeid)- 

 acetie aeid. 



ApvUcation of the chloroethers for the prepara- 

 tion of some new derivatives of diethyl malonate 

 and oarbituric acid: Akthur J. Hill and 

 DeWitt T. Keach. The present investigations 

 are preliminary to an extended study of the hyp- 

 notic effects produced by the introduction of vari- 

 ous ether rests in the 5 position in barbituric 

 acid (the methylene grouping). To this end 

 ehloromethyl ethyl ether and chloromethyl methyl 

 ether have been combined with the sodium salts 

 of diethyl malonate and ethyl diethyl malonate, 

 suspended in anhydrous ether. The following 

 esters have been thereby obtained: Di (ethoxy- 

 methyl) diethyl malonate, ethyl-ethoxymethyl 

 diethyl malonate, and ethyl-methoxymethyl diethyl 

 malonate. These derivatives of malonic ester 

 interact smoothly with urea in the presence of 

 alcoholic sodium ethylate, giving respectively: 

 5, 5-di (ethosymethyl) barbituric acid, 5, 5-ethyl- 

 ethoxymethyl barbituric acid, and 5, 5-ethyl- 

 methoxj-methyl barbituric acid. 



DIVISION OF RUBBER CHEMISTRY 



C. W. Bedford, chairman 

 Arnold H. Smith, secretary 

 The internal mixer as a factory unit: E. P. 

 DiNSMOKE. The study of the internal type of 

 rubber mixer in factory production has revealed 

 two defects. The ratio of cooling surface to vol- 

 ume of stock is so much less in such a mixer 

 than on a mill and the working is so much more 

 rapid that the temperature of the batch rises rap- 

 idly, and in most tire stocks it is impractical to 

 add sulphur before the batch is taken out of the 

 mixer. Also, these mixers require considerable 

 batehing-out equipment in order to sheet out the 

 finished stock thin enough so that it will cool in 

 a reasonably short time. The time for batching- 

 out does not vary greatly, and it is difficult to 

 balance mixing equipment with batching-out 

 equipment. The advantages to be gained from 

 the internal mixer are lower mixing costs, greater 

 freedom from the dust nuisance and lighter work 

 for the operator. 



The thermal properties of various pigments and 

 of rubber: Ira Williams. The thermal conduc- 

 tivity and diffusivity of rubber is determined by 

 two separate methods. A method for the deter- 

 mination of the conductivity of pigments is given 

 and the values have been determined for the most 

 common pigments used in rubber compounding. A 

 method is shown by which the thermal conductivity 



and diffusivity of any rubber compound may be 

 calculated from an analysis of the stock. 



Physical properties of rubber compounded with 

 light magnesium carbonate: H. W. Greider. The 

 physical properties of rubber compounded with 

 light magnesium carbonate have been studied, 

 including tensile strength, elongation, hardness, 

 resilient energy capacity and permanent set. This 

 material was shown to behave in rubber as a 

 reinforcing or toughening pigment, the maximum 

 effect being given by nine volumes of the filler to 

 100 volumes of rubber. The principal disadvan- 

 tage of magnesium carbonate in rubber was found 

 to be the high permanent set imparted to the vul- 

 canized product, attributable to the definite 

 crystalline character of the particles. The rein- 

 forcing effect of magnesium carbonate at nine 

 volumes per hundred of rubber was compared with 

 equal proportions of other reinforcing pigments, 

 including zinc oxide, gas black, fine china elay 

 and colloidal barium sulfate. Gas black was 

 shown to be the only filler showing a reinforcing 

 effect greater than that given by light magnesium 

 carbonate. 



The relation between chemical and physical 

 state-of-cure of rubber vulcanised in the presence 

 of certain organic accelerators : Norman A. Shep- 

 ARD and Stanley Krall. Hexamethylenetetra- 

 mine, aldehyde ammonia, p-nitrosodimethylaniline 

 and thiocarbaniUde, respectively, have been intro- 

 duced in such quantities into a mixing consisting 

 of 48 parts of first latex crepe, 48 parts of zinc 

 oxide and 3 parts of sulfur, that equivalent 

 physical states of cure (as gauged by the stress- 

 strain relations) were obtained in each ease when 

 vulcanized for 60 minutes at 287° F. The eoeffi- 

 eients of vulcanization of these cures show that 

 there is no uniform relationship between the 

 physical and chemical states of cure in these 

 stocks, even though the time and temperature of 

 curing are constant. The equivalent quantities 

 used in this work indicate that, in the tj-pe of 

 stock here examined, one part of hexamethyleue- 

 tetramine is equivalent in accelerating power to 

 one and one half parts of aldehyde ammonia, 

 three parts of thioearbanilide and one half part 

 of p-nitrosodimethylaniline, respectively. 



Physical testing graphs: W. B. Wiegand. 



Rubber Division methods for rubber analysis: 

 Report of committee and disctission. 



Organic accelerators. Symposium. Specification 

 standards and testing, including both chemical and 

 physical tests i?i compounds. 



Charles S. Parsons, 



Secretary. 



