February -1, 1921 



THE INDIA RUBBER WORLD 



33/ 



catalysts, while the final translorniation into resinous compounds 

 of indefinite composition, known as perishing, is possibly effected 

 by an entirely different set of activating and inhibiting agents. 



3. Though the retiuction in the solution viscosity v^hich char- 

 acterizes the first effects of light and oxygen on rubber can be 

 reproduced by the application of either heat or mechanical v^fork- 

 ing in the cold, it is doubtful whether the changes thereby pro- 

 duced in the rubber are in other respects analogous. 



4. In the presence of sulphur and under the influence of a light 

 source rich in ultra-violet, in place of depolynierization, a change 

 resembling vulcanization is induced. 



5. in the absence of air, tackiness will not develop in the 

 solid as a result of exposure to daylight, while a benzene-rubber 

 solution under similar conditions sets to a gel which liquifies on 

 recxposure to air. 



6. In the absence of aclinic light, rubber, either solid or in 

 solution, undergoes no reduction in viscosity as a result of ex- 

 posure to air, but if previously submitted to a limited amount 

 of mastication tends to regain its initial properties. This change 

 is, however, partially inhibited by oxygen. 



7. The efficiency of sulphur as a vulcanization agent, unless 

 supplemented by the presence of an appropriate accelerator, is neu- 

 tralized by the presence of oxygen. 



8. Under certain conditions oxygen would appear capable of 

 assuming the function of a vulcanizing agent. 



Ill considering the foregoing summary of the work in connec- 

 tion with the changes resulting from the action of oxygen and 

 light on rubber, it will be well to remember that the little which 

 is known is either related to chemical properties or else to one 

 physical characteristic, namely, viscosity. 



CARBON BLACK INDUSTRY IN LOUISIANA" 



The natural gas fields of Louisiana are considered the greatest 

 gas fields in the United States. The principal gas areas are 

 located in Caddo, Bossier, Cuachita and Morehouse parishes 

 extending across the northern border of the state and in Terre- 

 bonne parish on the Gulf Coast. The latter has wells yielding 

 the largest volume, some of them having been estimated at a 

 volume of 90,000,000 cubic feet per day. The Cuachita-More- 

 liouse field, approximately 30 miles long and 18 to 20 miles wide, 

 is unquestionably the greatest gas field known, with wells ranging 

 from 4,000,000 to 40,000,000 cubic feet daily capacity. 



The protection of this great natural gas asset with its enor- 

 mous unknown reserve has become a most serious problem. 

 Natural gas is recognized as a public asset which can yield 

 greater benefit to a larger number of people when utilized for 

 domestic consumption than in any other way. It is questionable, 

 therefore, if the public guaidians of such resources should permit 

 the use of natural gas for manufacturing purposes whicli mean 

 little in a direct way to the community or the state, as, for ex- 

 ample, its use for the manufacture of carbon black. 



CARBON BLACK PLANTS 



There arc possibly ten plants in the state now making car- 

 bon black from natural gas. They are consuming 70,000,000 

 cubic feet of gas per day. Unless some check is applied there 

 will be 20 of these plants within another year, which will con- 

 sume 140,000,000 to l.W.OOn.OOO cubic feet of gas per day. At this 

 rate the entire supply of natural gas would be use<l for the manu- 

 facture of carbon b'ack proI)ably within a few years, whereas 

 the economic distribution of tliis gas throughout the state would 

 result in untold benefit to hundreds of thousands of citizens for a 

 long period of time. 



It is not the purpose of the state to hoard the natural gas sup- 

 ply, and where found in isolated localities it is willing to permit 



^Address of Hon. M. L. Alexander. Commissioner of Conservation of 

 Lotlisiana, before tlie American Institute of Clieinical Engineers, Dccemljer, 

 1920, New Orleans, I.tnisiana. 



its use for other than domestic consumption. It is the purpose 

 of the state, however, to conserve the gas and to make it of eco- 

 nomic value to its people. 



The state is now requiring all carbon plants using natural gas 

 to extract its gasoline content before burning the gas for carbon. 

 All carbon companies are required to secure a permit from the 

 state before erecting their plants. These permits are to be re- 

 newed every twelve months ; renewal is dependent upon the supply 

 of gas. 



METHODS OF ANALYSIS 

 CHEIVIICAL EXAMINATION OF ANTIIWONY SULPHIDES' 



A VAN RossEM AND P. Dekker have investigated the methods 

 •'*■• proposed by Weber and Sweet." and Repony' for the anal- 

 ysis of antimony sulphide as regards (1) degree of acidity; (2) 

 free sulphur; (3) moisture and water of crystallization; f4) 

 calcium sulphate; (51 adulterations. They express their conclu- 

 sions as follows : 



Determining the percentage of free sulphur in antimony sul- 

 phide by extraction methods with organic solvents (carbon bi- 

 sulphide and acetone) is impracticable, as antimony pentasulphide 

 is decomposed by the solvents, free sulphide being liberated. 



A method has been devised for determining free sulphur in an 

 indirect way. This can be used on the condition that little or no- 

 trisulphide is present. 



C. O. Weber's method by dissolving antimony pentasulphide in 

 strong ammonia was extensively tested. It was found that this 

 method can be used only when (a) trisulphide is absent, (b) 

 dissolving the pentasulphide in ammonia of the smallest possible 

 concentration. 



The methods of Weber-Sweet and Repony for determining 

 moisture and water of crystallization, calcium sulphate and im- 

 purities were revised. 



INDIRECT DETERMINATION OF FREE SULPHUR 



One grain of antimony sulphide is boiled with 25 cc. of strong 

 hydrochloric acid (specific gravity 1.18) for about ten minutes, 

 then diluted with wafer and the insoluble part fihered off on a 

 r.ooch filter. Should tlie addition of water prodvice a white 

 precipitate add a little more hydrochloric acid. The crucible is 

 washed with hydrochloric acid, then with water, and dried at 90' 

 degrees C. The sulphur present is extracted with carbon bisul- 

 phide and weighed. 



WATER OF CRYSTALLIZATION OF CALCIUM SULPHATE 



Heating at 120 degrees C. expels only three-quarters of the 

 water of crystallization of calcium sulphate. It can be fully ex- 

 pelled only by heating at 3(X) degrees C. 



ADULTERATIONS IN ANTIMONY SULPHIDE 



Different investigators determine possible adulterations by 

 treating the antimony pentasulphide with caustic potash or soda, 

 solution causing such impurities as kaolin, iron oxide, etc., to 

 remain behind. For example, after extraction with carbon bi- 

 sulphide and water, Repony dissolves the remaining part in ten- 

 per cent caustic soda solution on the water bath. .A.t the Institute 

 five samples were tested in this way. Thus it appeared that when 

 the heating on the water bath was prolonged, tlie quantity of in- 

 soluble material became greater, due to the fact on dissolving 

 antimony pentasulphide in caustic soda solution, insoluble sodium 

 antimoniate is formed 



The insoluble part of the five samples referred to was yellowish 

 white, and was entirely soluble in hydrochloric acid, which proved" 

 that none of the samples tested contained adulterations insoluble 

 in acid. In order to state the nature of the adulterations analysis 

 of the part insoluble in caustic soda solution is necessary. 



'Special comnmnic.ition of tlic Netlierland Government InElit\:te. Delft 

 10 Tlie India-Rubber Journal. Oclolier .10. 1920. 



' Le Caoutchouc et la flutta-I'crcha. \S. 9468 (19IS). 

 = TllE r.vDiA Rriinrii Wobid. .\|.ril 1. 1919. page 360. 



