137 



nitric acid is used, the object being to form elastic substances similar 

 to linoxyn. ' Stiffeners such as resin, pitch, tar, acacia, tragacanth, 

 and albuminoids such as gelatin or casein, may be added, as also 

 "filling" materials, including chalk, magnesia, silica, kaolin, zinc 

 oxide, cork, sawdust, chopped feathers, and waste leather. The 

 product is vulcanised in the usual manner, frequently with the addi- 

 tion of waste or regenerated rubber, and is then used for lower-grade 

 goods. The elastic product yielded by heating nitrated castor oil to 

 130'C., for ten hours is the subject of a patent by the Velvril Co. 

 Passing ozone through a mixture of castor oil containing colophony 

 and sulphur is a variation of the oxidation process patented in 

 America, the product being finally heated with sulphur chloride. 

 Ditmar (1906), in his specification for a process for the removal of 

 unvulcanised oil by means of solvents, states that the defects in 

 substitutes are due mainly to its presence. Gelatin or glue, with or 

 without admixture of glycerin, rendered insoluble by treatment with 

 formaldehyde or chormic acid, gives another form of rubber substitute. 

 The viscous masses obtained by heating carbohydrates, such as sugar 

 and starch, are the subjects of patents, as also elastic plastic masses 

 stated to result from the action of acetylene and oxygen on a mixture 

 of copper and nickel, the metals acting as catalyst. Rouxville (1906) 

 filed a specification in France for producing caoutchouc, etc., from 

 terpenes (turpentine), but did not complete the patent in England. 

 The conclusion arrived at is that cheaper rubber of improved quality 

 is more likely to be derived from increased production by recent 

 rubber-plantations than by artificial production. — The Chemist and 

 Druggist, January I, 1910, Page 19). 



On the effect of Arsenical and Sulphur Fumes 

 on Vegetation, with particular reference to 

 the Para Rubber Tree [Hevea Brasilicnsis) and 

 Rambong [Ficus Elastica). 



Note: — With reference to the article on this subject appearing 

 in the Agricultural Bulletin, February, 1910, Vol. IX., No. 2, page 46 

 et seq. it has been pointed out to me that the data sh(5wing the total 

 period during which roasting was carried on might possibly be under- 

 stood to be fifteen days, and that the " Observations on the fifteenth 

 day " might indicate that the plants had by this time become immune 

 to the effects of the fumes. 



On page 47, under the heading " Method of Roasting," it is 

 stated that the roasting was continued for twelve hours. Only one 

 batch of ore of 80 lbs. was roasted for a period of twelve hours and 

 the effects produced on the plants were caused entirely by this single 

 roasting, the first effects being observed on the second day after the 

 roasting had cleased and continuing till over the 7th day, after which 

 no further effects were observed, and the plants gradually recovered ; 

 the recovery being well advanced and the plants forming a number 

 of new leaves by the fifteenth day. 



B.J. EATON, 

 Government Chemist, F. M. S. 



