October 1, 1916.] 



THE INDIA RUBBER WORLD 



11 



streams of air directly upon the men while they are at their 

 operating positions. In fair weather the windows are removed, 

 at other times satisfactory floor ventilation is provided. Suction 

 ventilating ducts are led directly to stuffing boxes and iron 

 boring feeders, where there is always more or less escaping 

 vapor. The manufacturing system is closed, so that it is un- 

 necessary for open aniline to be handled. Drinking men are 

 excluded from the operating force. The men are provided by 

 the company with regular rations of milk, with two clean work- 

 ing uniforms weekly per man, and with rubber boots. Shower 

 baths are installed and their daily use insisted upon. Frequent 

 inspection for leaks is made of pumps, valves and stuffing boxes. 

 The necessity of replacing the stirring paddles in the aniline 

 reducers is the cause of many of the poisoning cases observed. 

 In spite of continued washing and steaming out, there is suf- 

 ficient anilinir saturating the residual iron borings in the reducer 

 bottom to make it inadvisable for men to remain in the reducer 

 for more than a half hour. 



METHODS OF ANALYSIS. 



IN the article "Select Methods of Analysis of Golden 

 Sulphide of Antimony" published in this department in 

 August, credit was unintentionally omitted. It was con- 

 densed from the original in "Le Caoutchouc & la Gutta- 

 percha," by Andre Dubosc. 



The following article is by the same author and also from the 

 same publication : 



SULPHIDES OF ANTIMONY AND THEIR ANALYSIS. 



Golden sulphuret of antimony or pentasulphide of antimony 

 is an important factor in the manufacture of inner tubes, drug- 

 gists' and surgical rubber goods. 



The pentasulphide is in non-stable equilibrium and under the 

 increase of temperature, which occurs in the course of hot vul- 

 canization, releases colloidal sulphur, which unites with rubber 

 easier than flowers of sulphur. 



This dissociation occurs at 130 to 135 degrees C, leaving as 

 residuary product red trisulphide of antimony, a pigment, giving 

 to the product the beautiful red color sought by the trade. 



Red trisulphide under the same conditions, does not give the 

 same results as the pentasulphide. It does not release the col- 

 loidal sulphur necessary for vulcanization. At 130 to 135 de- 

 grees C, it has a tendency to change into black sulphide. In- 

 stead of red goods, brownish unsightly products are obtained. 



Under these conditions, one can realize the importance, from 

 a practical standpoint, of knowing the trisulphide content of 

 the golden sulphurets offered by dealers. 



The manufacture of golden sulphuret of antimony is much 

 more delicate than many imagine it to be and, even when start- 

 ing from Schlippe's salts, very minute precautions must be taken 

 to escape changing the pentasulphite or real golden sulphuret of 

 antimony into the almost valueless trisulphide of antimony. 



That is what many do not know and it explains the lack of 

 value of some of the products found in the market. 



Following arc a few analyses of such products offered in the 

 trade, which, in view of their composition, will not give com- 

 plete satisfaction in vulcanizing. 



GOLDEN SULPHURET A. 



Pentasulphide of Antimony 2L900% 



Trisulphjde of Antimony 77.960% 



GOLDE-NT SULPHURET B. 



Pentasulphide of Antimony 43.000% 



Trisulphide of Antimony 57.000% 



GOLDEN SULPHURET C. 



Pentasulphide of Antimony 57.825% 



Trisulphide of Antimony 40.735% 



GOLDEN SULPHURET D. 



Pent.^sulphide of Antimony 23.291% 



Trisulphide of .\ntimonv 76.029% 



Most of these products, owing to their high content of tri- 

 sulphide, are only interesting as pigments; for, as vulcanizers, 

 their reaction is very weak. 



Such goods should be replaced by the types which contain lime 

 sulphate as impurity, but in which all the antimony is in the form 

 of pentasulphide as shown in the following analysis: 



ANTIMONY SULPHIDE P No. 1. 



Pentasulphide of Antimony 64.692% 



Free Sulphur 13.420% 



Lime Sulphate 9.852% 



Oxide of Antimony 12.046% 



ANTIMONY SULPHIDE P No. 2. 



I'entasulpiiide of Antimony 56.998% 



Free Sulphur 15.000% 



Lime Sulphate 28.002% 



ANTIMONY SULPHIDE F No. 3. 



Pentasui phide of .Antimony 68.099% 



Frie Suiphur 18.000% 



Lime Sulphate 13.901% 



These products are perfectly manufactured. They were ob- 

 tained starting from Schlippe's crystallized salt, and are pre- 

 cipitated by sulphuric acid. Their only impurity is lime 

 sulphate. 



With pentasulphides, like those of series P, the reduction does 

 nut extend to black sulphide, but stops at red sulphide, yielding 

 colloidal sulphur, and therefore permitting ( 1 ) a more rapid 

 vulcanization; (2) a perfect red and not a brownish coloring. 



TOTAL SULPHUR IN RUBBER. 



Davies' method consists in treating a half gram of finely 

 ground vulcanized rubber in a 300 cc. Erienmeyer flask with 

 15 cc. of saturated solution of arsenic acid, 10 cc. of fuming 

 nitric acid and 3 cc. of saturated bromine water. The mixture 

 is covered and boiled till oxidation is complete and the solu- 

 tion clear. If needed, more nitric acid may be added. The 

 solution is evaporated to syrupy consistency, a few crystals 

 of potassium chlorate added, and evaporation continued 

 nearly to complete dryness, to expel entirely the oxides of 

 nitrogen. After cooling, take up in 50 cc. of 10 per cent 

 hydrochloric acid, heating over a water bath until solution 

 is complete. The insoluble matter is separated by filtration 

 and the filtrate diluted to 300 cc. from which the sulphate is 

 precipitated in the usual manner. 



The action of the arsenic acid is to raise the boiling point 

 of the solution and to produce oxidation. The reagent is pre- 

 pared by addition of arsenious anhydride to water till its 

 boiling point is raised to 284 degrees F. 



COLOPHONY m SHELLAC. 



A. Hutin in "Le Caoutchouc & la Gutta-Percha" discusses 

 the adulteration of shellac and describes his methods for 

 qualitative and quantitative determination of colophony 

 w-hich is u common addition for cheapening shellac. 



QuALiT.\TivE Test.— .\ gram of finely powdered gum lac is 

 saponified with a slight excess of caustic soda, diluted with 

 water and slight excess of copper sulphate solution added. 

 If colophony is present resinate of copper is formed which 

 will give a green color to turpentine. Pure gum lac under 

 these conditions gives no indication. 



QuANTiT.^TivE Tests. (a) A gram of finely pulverized shel- 

 lac is dissolved in 97 or 98 degree alcohol. Sand is added to 

 form a mass and the whole evaporated to dryness on a water 

 bath. The process of solution in alcohol, addition of sand and 

 drying is performed three times to eliminate the gum lac, each 

 time the mass being scraped from the dish. The gum lac and 

 sand from these operations is extracted in a Soxhlet for four 

 hours with chloroform. The colophony is dissolved, while 

 the gum lac is not affected, (b) Add to one gram of finely 

 powdered gum lac SO cc. of 10 per cent borax solution. The 

 gum lac will dissolve, but the colophony will not. Should 

 the gum lac contain a phenol-formaldehyde condensation 

 product as an adulterant, the latter would not dissolve in the 



