136 



a caoutchouc) is seeded with caoutchouc particles or treated with 

 other appropriate ferment at 6o°C. in an atmosphere of nitrogen. 

 Later a method was patented of preparing the " ferment." To 

 obtain this the " thick deposit " from a caoutchouc solution in 

 benzine, kept at a temperature of 50X. and exposed to daylight in a 

 closed bottle, is re-dissolved and then precipitated again by alcohol. 

 The precipitate is scattered over the surface of a mixture of coal tar 

 and boric acid which is maintained at SoX. in an atmosphere of 

 oxygen. A brownish-grey powder is stated to be formed on the 

 walls, and this is the " ierment " in an active form. Prior to the 

 last process, Jasset (1902) stated in his specification that coal tar 

 (4 parts) and boric acid (I part), heated until the burning vapours 

 were coloured green and then kept at 60' C. in a current of oxygen, 

 yielded a brown highly elastic body to suitable solvents after drying 

 on a water-bath. Phosphoric or iodic acid may replace boric acid. 

 An American patent, by Dupont and Franklin (1903) gives a variation 

 of the above, since the tar and boric acid are dissolved in alcohol, 

 heated until vapours burning with green flame are evolved, then 

 oxygen is passed through the mixture. Blum and Carpenter (French 

 patent, 1909) propose to obtain a glutinous mass consisting of a 

 hydrocarbon of the formula ( C5 Hg )4 by subjecting vegetable 

 substances, such as peat, to fermentation at about 60' C, and smiul- 

 taneously or subsequently to a reducing process. The enzyme is 

 stated to be present in imperfectly formed caoutchouc, or an "enzyme 

 which will produce alcohols of a series higher than the ole fine series " 

 may be used. The reducing agent is a nitrogenous compound, pre- 

 ferably the red substance resembling seed in red Upper Congo rubber, 

 with the addition of mineral salts. In 1908 the same two patentees 

 specified a process to produce " synthetic Para rubber " by treating 

 with a nitrogenous derivature of irone, the mucilaginous mass " con- 

 taining a large percentage of isoprene " produced from fermented 

 peat, etc. The irone was stated in a subsequent patent to be obtained 

 from roots of'species of Iris. The irone is converted by chlorine into 

 a hydrochloride, then by addition of a suitable substance, preferably 

 an amide, into a nitrogenous compound. Protein-coagulating enzymes 

 are known to occur in the latex of rubber-producing plants, but 

 exactly in what form caoutchouc pre-exists is not known ; but to 

 produce artificial rubber from tar by a volatile enzyme capable of 

 growth does not accord with known facts. 



Rubber substitutes have met with greater success since at present 

 considerable difficulty is experienced in obtaining rubber goods free 

 from substitutes. Their use as a cheapener is responsible for many 

 of the defects to which rubber articles are liable. The non-resistance 

 of rubber substitutes to the action of potassium hydrate is the method 

 used for the detection and estimation of substitutes. Among the 

 multifarious substances proposed to be employed for the diluting 

 rubber the oxidation-products of drying-oils are the basis of the main 

 modern class. Dry oxidation of a suitable fixed oil, usually linseed 

 oil, is affected with a manganese dioxide, etc., or in the wet process 



